Glossary Glossary Glossary of Primate Higher Taxa abductor A muscle that moves a part of the body away from the midline of the body. ABO blood-type system A blood-type system that consists of two basic antigens, A and B. Blood type O is the absence of both antigens. acclimatory adjustment Reversible physiological adjustments to stressful environments. accretion Growth by virtue of an increase in intercellular material. Acheulean tradition The most frequent cultural manifestation of the Lower Paleolithic; characterized by several highly diagnostic tool types, including the hand ax. achondroplastic dwarfism Form of dwarfism in which the individual's head and trunk are of normal size but the limbs are quite short; inherited as a dominant. achromatopsia A recessive genetic abnormality in which the retina of the eye lacks the cones that are necessary for color vision and for seeing in fine detail. Also called total color blindness. acid rain Rain that carries acids that pollute water systems and soils. adaptation Changes in gene frequencies resulting from selective pressures being placed on a population by environmental factors; results in a greater fitness of the population to its ecological niche. adaptive radiation The evolution of a single population into a number of different species. adenine One of the bases found in DNA and RNA; a purine. adenosine triphosphate (ATP) The main fuel of cells. ATP is manufactured by the mitochondria. adjustment The ability of humans to survive in stressful environments by nongenetic means. adolescent growth spurt A rapid increase in stature and other dimensions of the body that occurs during puberty. adult The period in an individual's life cycle after the eruption of the last permanent teeth. agglutination A clumping together of red blood cells in the presence of an antibody. aging The uninterrupted process of normal development that leads to a progressive decline in physiological function and ultimately to death. agonistic behavior Behavior that involves fighting, threats, and fleeing. albinism A recessive abnormality that leads to little or no production of the skin pigment melanin. alcaptonuria A recessive genetic abnormality that results in the absence of an enzyme that is involved in the breakdown of the amino acid tyrosine, bringing about a buildup of homogentisic acid in the body which is deposited in various organs of the body. allele An alternative form of a gene. Allen's rule Among mammals, populations of the same species living near the equator tend to have body parts that protrude more and to have longer limbs than do populations farther away from the equator. allogrooming Grooming another animal. allometric growth Pattern of growth whereby different parts of the body grow at different rates with respect to each other. allopatric species Species occupying mutually exclusive geographical areas. altruism Behavior characterized by self-sacrifice that benefits others. alveoli Small air sacs, located in the lungs, that are richly endowed with blood capillaries. Oxygen is absorbed by the blood in the alveoli. amino acid A type of molecule that forms the basic building block of proteins. amino acid racemization Chronometric dating method based on change in the three-dimensional structure of amino acids from one form to its mirror image over time. amniocentesis A medical technique in which amniotic fluid is removed for study of the fetus. amniote egg An egg with a shell and several internal membranes, which made reproduction on land possible. amniotic fluid The fluid surrounding the fetus. analogies Structures that are superficially similar and serve similar functions but have no common evolutionary relationship. anterior pillars Bony columns located on both sides of the nasal aperture of some fossil hominids that help withstand the stresses of chewing. anthropocentricity The belief that humans are the most important elements in the universe. anthropoid A member of the suborder Anthropoidea; includes the New World monkeys, Old World monkeys, apes, and humans. anthropological linguistics The study of language in cross-cultural perspective; the origin and evolution of language. anthropology The broad-scope scientific study of people from all periods of time and in all areas of the world. Anthropology focuses on both biological and cultural characteristics and variation as well as biological and cultural evolution. anthropometry The study of measurements of the human body. antibody A protein manufactured by the body to neutralize or destroy an antigen. antigen A substance that stimulates the production or mobilization of antibodies. An antigen can be a foreign protein, toxin, bacterium, or other substance. ape A common term that includes the small-bodied apes (the gibbons and siamang) and the great apes (the orangutan, chimpanzee, bonobo, and gorilla). applied anthropology A branch of anthropology devoted to applying anthropological theory to practical problems. arbitrary A characteristic of language. A word or another unit of sound has no real connection to the thing to which it refers; the meanings of the arbitrary elements of a language must be learned. arboreal Living in trees. archaeology The scientific study of the past and current cultures through the analysis of artifacts and the context in which they are found. archeomagnetism A dating technique that uses a determination of declination angle in archaeological samples. archetype The divine plan or blueprint for a species or higher taxonomic category. areolar area The dark area surrounding the nipple of the breast. argon 40/argon 39 dating A method of chronometric dating based on making measurements of the relative amounts of argon 40 and argon 39 in a sample. artifact Any physical remains of human activity. artificial gene A gene that is made in a laboratory and used in place of a defective or undesirable gene. artificial selection The deliberate breeding of domesticated animals or plants. assemblage All the artifacts from a given site. assortative mating Preference for or avoidance of certain people as mates for physical or social reasons. aster In cell division, the fibers that radiate from the centrosome. asymmetry of function The phenomenon in which the two hemispheres of the brain specialize in regard to different functions. atom A building block of matter. Australopithecines Members of the genera Australopithecus and Paranthropus, who lived in African approximately 4 to 1 million years ago. autapomorphic feature A feature that is unique to a particular species. autogrooming Self-grooming. autosome A chromosome other than a sex chromosome. awl A type of tool that is used to puncture a hole in a soft material such as wood or skin. back cross The process of crossing a hybrid with its homozygous recessive parent. balanced polymorphism Maintenance of two or more alleles in a gene pool as the result of heterozygous advantage. band Among geladas, a social group consisting of a number of harems and all-male units. Among humans, the basic social unit of hunting and gathering peoples, which typically consists of about 25 members. basal metabolic rate The measure of the total energy utilized by the body to maintain those body processes necessary for life; the minimum level of heat produced by the body at rest. base A subunit of a nucleotide that makes up the DNA and RNA molecules: adenine, cytosine, guanine, thymine, uracil. basicranium The floor of the brain case. behavioral adjustment Survival in a stressful environment made possible by cultural means, primarily technology. behavioral thermoregulation Using behavior, such as avoiding or seeking sources of heat, to regulate body temperature. Bergmann's rule Within the same species of mammals, populations with less bulk are found near the equator while those with greater bulk are found farther from the equator. Beringia The landmass, some 2000 kilometers (1250 miles) from north to south, that connected Siberia and Alaska during the glacials. biacromial width A measurement of the width of the shoulders. bilophodont Refers to a form of molar found in Old World monkeys consisting of four cusps with a small constriction separating them into two pairs. binocular field The visual field produced by the overlapping of the separate visual fields from each eye when the eyes are located on the front of the face. binomen A two-part name given to a species; the first name is also the name of the genus. An example of a binomen is Homo sapiens. binomial nomenclature A system of naming species that uses a double name such as Homo sapiens. The first name alone names the genus; both names used together name the species. bioinformatics A new discipline dedicated to the analysis of genetic information and the practical use of that information. biological environment The living elements surrounding the organism. biological evolution Change in the frequencies of alleles within a gene pool of a population over time. bipedalism See erect bipedalism. bitrochanteric width A measurement of hip width. blade Flakes with roughly parallel sides and extremely sharp edges; blades are frequently found in Upper Paleolithic sites. blending theory An early and incorrect idea that the inherited characteristics of offspring are intermediate between maternal and paternal genetic characteristics. bone age A standard age based on the appearance of centers of ossification and fusion of growth plates. bone breccia Cave fill consisting of masses of bone cemented together with calcium carbonate that has dissolved out of limestone. bone industry All of the bone artifacts from a particular site. brachial index The length of the radius relative to the length of the humerus. brachiation Hand-over-hand locomotion along a branch with the body suspended underneath the branch by the arms. branch running and walking A form of quadrupedalism in which the animal is walking along a branch, grasping with both hands and feet. breast bud An elevation of the breast as a small mound; the earliest sign of puberty in the female. Broca's area A small area in the human brain that controls the production of speech sounds. Bronze Age The stage of cultural history that includes the earliest civilizations and the development of metallurgy. brow ridge Ridge of bone above the eye sockets. burin A stone tool with a chisel-like point used for engraving or manufacturing bone tools. calendrical system A system of measuring time based on natural recurring units of time, such as the revolutions of the earth around the sun; they note the number of such units that have preceded or elapsed with reference to a specific point in time. call system A system of vocalized sounds that grade one into another. carbohydrates Organic compounds composed of carbon, oxygen, and hydrogen; include the sugars and starches. carnivore An animal that eats primarily meat. carrier A person who possesses a recessive allele in the heterozygous condition. cast A representation of an organism created when a substance fills in a mold. catarrhine nose Nose in which nostrils open downward and are separated by a narrow nasal septum; found in Old World monkeys, apes, and humans. catastrophism Idea that the earth has experienced a series of catastrophic destructions and creations and that fossil forms found in each layer of the earth are bounded by a creation and destruction event. cell The smallest unit able to perform all those activities collectively called life. All living organisms are either one cell or composed of several cells. centriole A pair of small bodies found near the nucleus of the cell from which the spindle is formed. centromere A structure in the chromosome holding the two chromatids together; during cell division, it is the site of attachment for the spindle fibers. centrosome A body that lies near the nucleus of the cell that contains two centrioles. cephalic index The breadth of the head relative to its length. cerebral cortex The "gray matter" of the brain; the center of conscious evaluation, planning, skill, speech, and other higher mental activities. cheek pouch Pocket in the cheek that opens into the mouth; some Old World monkeys store food in the cheek pouch. cheek teeth The premolars and molars. chin A bony projection of the lower border of the outside of the mandible. chordate A member of the phylum Chordata; chordates are characterized by the presence of a notochord, a dorsal, hollow, single nerve cord, and gill slits at some point in the life cycle. chromatid One of the two strands of a replicated chromosome. Two chromatids are joined together by a centromere. chromosomal aberration Abnormal chromosome number or chromosome structure. chromosomal sex The number of X and Y chromosomes a person has. The chromosomal sex of a person with two X chromosomes is a female. The chromosomal sex of a person with one X and one Y chromosome is a male. chromosome A body found in the nucleus of the cell containing the hereditary material. chron A large division of a geomagnetic time scale that shows primarily a single polarity. chronological age Period of time since birth. chronometric dates Dates that refer to a specific point or range of time. Chronometric dates are not necessarily exact dates, and they often are expressed as a probability. chronospecies Arbitrarily defined divisions of an evolutionary line. civilization A type of society with relatively high population density; based on the de-emphasis of kinship as a method of social control and the rise of central authority in the form of a government and powerful priesthood. Civilizations often also include monumental architecture, writing, mathematics, public works, and full-time armies. clade A group of species with a common evolutionary ancestry. cladistics A theory of classification that differentiates between shared ancestral and shared derived features. cladogram A graphic representation of the species, or other taxa, being studied, based on cladistic analysis. class Major division of a phylum, consisting of closely related orders. classification A system of organizing data. cleaver A large core tool with a straight, sharp edge at one end. clinal distribution A distribution of frequencies that show a systematic gradation over space; also called continuous variation. cloning The process of asexual reproduction in an otherwise multicellular animal. codominance The situation in which, in the heterozygous condition, both alleles are expressed in the phenotype. codon A sequence of three bases on the DNA molecule that codes a specific amino acid or other genetic function. coefficient of relatedness A measurement of the degree of genetic relationship or the number of shared genes between two individuals. communication Occurs when some stimulus or message is transmitted and received; in relation to animal life, when one animal transmits information to another animal. community Among chimpanzees, a large group that, through fission and fusion, is composed of a series of constantly changing smaller units, including the all-male party, family, unit, nursery unit, consortship, and gathering. comparative cytogenetics The comparative study of chromosomes. competition The situation in which two populations occupy the same or parts of the same niche. complementary pair A set of two nucleotides, each on a different polynucleotide chain, that are attracted to each other by a chemical bond. In DNA, adenine and thymine, and cytosine and guanine, form complementary pairs. compound tool A tool that is composed of several parts, for example, a harpoon. computerized tomography A technology used in medicine that permits visualization of the interior of an organism's body. conduction The movement of heat from one object to another by direct contact. cones Cells of the retina of the eye; each of the three types of cones is sensitive to a specific wavelength of light, thereby producing color vision. consanguineous mating Mating between biological relatives. consort pair A temporary alliance between a male and an estrus female. constitutive heterochromatin Chromosomal material that is not thought to contain any actual genes. control In an experiment, a situation in which a comparison can be made between a specific situation and a second situation that differs, ideally, in only one aspect from the first. convection Movement of heat from an object to the surrounding fluid, either gas or liquid; heat causes the gas or fluid to move away from the object. convergence Nonhomologous similarities in different evolutionary lines; the result of similarities in selective pressures. coprolite Fossilized fecal material. core A nodule of rock from which flakes are removed. core area Sections within the home range of a primate population that may contain a concentration of food, a source of water, and a good resting place or sleeping trees, and in which most of the troop's time will be spent. core tool A tool that is manufactured by the removal of flakes from a core. cranial capacity The volume of the brain case of the skull. creation-science The idea that scientific evidence can be and has been gathered for creation as depicted in the Bible. Mainstream scientists, many religious leaders, and the Supreme Court discount any scientific value of "creation-science" statements. critical temperature The temperature at which the body must begin to resist a lowering of body temperature; occurs in the nude human body at approximately 318C (87.88F). cross-cousin preferential marriage Marriage between a person and his or her cross-cousin (father's sister's child or mother's brother's child). crossing-over The phenomenon whereby sections of homologous chromosomes are interchanged during meiosis. crural index The length of the tibia relative to the length of the femur. cultural anthropology The study of the learned patterns of behavior and knowledge characteristic of a society and of how they vary. cultural environment The products of human endeavor, including technology and social institutions surrounding the organism. culture Learned, nonrandom, systematic behavior and knowledge that can be transmitted from generation to generation. culture-bound The state or quality of having relevance only to the members of a specific cultural group. cusp A point on a tooth. cystic fibrosis A recessive genetic abnormality that affects the production of mucus in the lungs. cytogenetics The study of the heredity mechanisms within the cell. cytology The study of the biology of the cell. cytoplasm Material within the cell between the plasma membrane and the nuclear membrane. cytosine One of the bases found in the DNA and RNA molecule; a pyrimadine. Darwinian medicine A field of medicine that attempts to understand the human vulnerability to diseases and other medical conditions in terms of evolutionary theory. debitage Waste and nonutilized material produced in the process of tool manufacture. deciduous teeth The first set of teeth that develop in mammals; also known as the baby or milk teeth. declination angle At a particular point on the surface of the earth, the angle formed by a line pointing to true north and a line pointing to magnetic north. deletion A chromosomal aberration in which a chromosome breaks and a segment is not included in the second-generation cell. The genetic material on the deleted section is lost. deme The local breeding population; the smallest reproductive population. dendrochronology Tree-ring dating. dental arcade The tooth row as seen from above. dental comb A structure formed by the front teeth of the lower jaw projecting forward almost horizontally; found in prosimians. dental formula Formal designation of the types and numbers of teeth. The dental formula 2.1.2.32.1.2.3 indicates that in one-half of the upper jaw and lower jaw there are two incisors, one canine, two premolars, and three molars. deoxyribonucleic acid (DNA) A nucleic acid that controls the structure of proteins and hence determines inherited characteristics; genes are portions of the DNA molecule that fulfill specific functions. deoxyribose A five-carbon sugar found in the DNA molecule. development The process whereby cells differentiate into different and specialized units; change over time from an immature to a mature or specialized state. developmental adjustments Alterations in the pattern of growth and development resulting from environmental influences. diabetes Failure of the body to produce insulin, which controls sugar metabolism; has a complex genetic basis influenced by environmental factors. diaphragm A muscle that lies beneath the lungs. When the diaphragm contracts, the volume of the lungs increases, causing a lowering of pressure within the lungs and movement of air from the outside into the lungs. When the diaphragm relaxes, air is expelled from the lungs. diastema A space between teeth. dichromacy The possession of two visual pigments, sensitive to blue and green, in the retina of the eye. diphyodonty Having two sets of teeth, the deciduous and the permanent teeth. directional selection A type of natural selection characterized by a generation-after-generation shift in a population in a specific direction, such as toward larger body size. In this example, individuals with smaller body size are being selected against. discontinuous variation Distribution of alleles, allele combinations, or any traits characterized by little or no gradation in frequencies between adjacent regions. discrete A characteristic of language. Signals, such as words, represent discrete entities or experiences; a discrete signal does not blend with other signals. displacement (behavior) The situation in which one animal can cause another to move away from food, a sitting place, and so on. displacement (language) A characteristic of language. The ability to communicate about events at times and places other than when and where they occur; enables a person to talk and think about things not directly in front of him or her. disruptive selection A type of natural selection characterized by a generation-after-generation shift in the population away from the average individual, such as, for example, toward both larger and smaller body size. In this example, individuals with average (mean) body size are being selected against. distance curve A graph that shows the total height (or other measurement) of an individual on a series of dates. diurnal Active during daylight hours. dizygotic twins Fraternal twins; twins derived from separate zygotes. domestication The control of the reproductive cycle of plants and animals. dominance (behavior) Behavior in which one animal displaces another and takes preference in terms of sitting place, food, and estrus females. dominance (genetic) When in the heterozygous genotype only one allele is expressed in the phenotype, that allele is said to be dominant. dominance hierarchy A system of social ranking based on the relative dominance of the animals within a social group. dorsal Toward the top or back of an animal. Down syndrome Condition characterized by a peculiarity of eyefolds, malformation of the heart and other organs, stubby hands and feet, short stature, and mental retardation; result of extra chromosome 21. duplication Chromosomal aberration in which a section of a chromosome is repeated. dyspnea Difficult or painful breathing. ecological isolation Form of reproductive isolation in which two closely related species are separated by what is often a slight difference in the niches they occupy. ecological niche The specific microhabitat in which a particular population lives and the way that population exploits that microhabitat. ecology The study of the relationship of organisms or groups of organisms to their environment. edema Retention of water in the tissues of the body. electron spin resonance (ESR) dating A chronometric dating technique based on the behavior of electrons in crystals exposed to naturally occurring radioactivity; used to date limestone, coral, shell, teeth, and other materials. Ellis-van Creveld syndrome A rare recessive abnormality characterized by dwarfism, extra fingers, and malformations of the heart; high incidence among the Amish. empirical Received through the senses (sight, touch, smell, hearing, taste), either directly or through extensions of the senses (such as a microscope). encephalization quotient (EQ) A number reflecting the increase in brain size over and beyond that explainable by an increase in body size. endocranial cast A cast of the inside of the brain case. endocrine disruptors Natural and synthetic chemicals that affect the endocrine system. endocrine glands Organs that produce hormones. endocrine system A network of glands that, through the production of hormones, control the body's internal functions. environment Everything external to the organism. environmental estrogens Synthetic or natural endocrine disruptors that may find their way into water, soil, air, and food and may affect the endocrine system. enzyme A molecule, usually a protein, that makes a chemical reaction happen or speeds up a slow chemical reaction. It is not itself altered in the reaction. epidemiology The study of the distribution and causes of disease and injury in human populations. epidermal ridges The pattern of ridges found on the hands and feet that form "fingerprint" patterns. These ridges are richly endowed with nerve endings that are associated with a refined sense of touch. epidermis The outermost layer of the skin. epoch A unit of geological time; a division of a period. era A major division of geological time defined by major geological events and delineated by the kinds of animals and plant life it contains. Humans evolved in the Cenozoic era. erect bipedalism A form of locomotion found in humans in which the body is maintained in an upright posture on two legs while moving by means of a heel-toe stride. erythroblastosis fetalis A hemolytic disease affecting unborn or newborn infants caused by the destruction of the infant's Rh1 blood by the mother's anti-Rh antibodies. erythrocyte Red blood cell; cell found in blood that lacks a nucleus and contains the red pigment hemoglobin. estrogen Hormone produced in the ovaries. estrus Time period during which the female is sexually receptive. ethnic group A group of people who share a common culture including traditions, language, religion and history. eugenics The study of the methods that can improve the inherited qualities of a species. evaporation Liquid is transformed into a gas utilizing energy. evolution See biological evolution. evolutionary psychology The study of the role of biology and natural selection on human behavior. experiment A test of the predictive value of a hypothesis. A controlled experiment compares two situations in which only one factor differs. extensor A muscle that straightens out the bones about a joint. extinction The disappearance of a population. facial sinus An air-filled space lined with a mucous membrane in the bones of the front of the skull. faculty of language in the broad sense (FLB) Shared communicative capabilities of humans and some nonhumans that include motor and neurological systems that allow interaction with the world and physical and neurological systems that allow creation of sounds and movements that have the potential to communicate. faculty of language in the narrow sense (FLN) Characteristics of language that are unique to humans, such as recursion. familial hypercholesterolemia A rare dominant abnormality controlled by a multiple-allele series of at least four alleles. The disease is caused by a defective protein that can result in extremely high levels of cholesterol in the blood. family Major division of an order, consisting of closely related genera. female-bonded kin groups Primate social groups that are based on associations of females. field study A study conducted in the natural habitat of an animal with minimal interference in the animal's life. fission-fusion society Constantly changing form of social organization whereby large groups undergo fission into smaller units and small units fuse into larger units in response to the activity of the group and the season of the year. fission-track dating The determination of a chronometric date by counting the proportion of atoms of a radioactive isotope such as uranium 238 that have decayed, leaving visible tracks in a mineral, relative to the total number of atoms of the isotope. fitness Measure of how well an individual or population is adapted to a specific ecological niche as seen in reproductive rates. flake A small piece of stone that is removed from a core when the core is struck by a hammerstone or bone hammer. flake tool A tool manufactured from a flake. fluorine dating A method for determining whether two fossils found in the same level of the same site are contemporary by measuring the amount of fluorine absorbed by the fossils. fluted Referring to fluted points where a rounded groove has been made in the shaft of the point, most likely to facilitate hafting. folivore An animal that eats primarily leaves. folk taxonomy Classification of some class of phenomena based on cultural tradition. foramen magnum A large opening in the occipital bone at the base of the skull through which the spinal cord passes. foramina Small holes found in bone that permit the passage of nerves and blood vessels. forebrain The anterior of three swellings in the hollow nerve cord of the primitive vertebrate brain formed by a thickening of the wall of the nerve cord. forensic anthropology Application of the techniques of osteology and skeletal identification to legal problems. fossil Remains or trace of any ancient organism preserved in the ground. founder principle Situation in which a founding population does not represent a random sample of the original population; a form of sampling error. four-chambered heart A heart that is divided into two sets of pumping chambers, effectively separating oxygenated blood from the lungs from deoxygenated blood from the body. fovea A depression within the macula of the retina of the eye that contains a single layer of cones with no overlapping blood vessels; region of greatest visual acuity. frugivore An animal that eats primarily fruits. gamete A sex cell produced by meiosis that contains one copy of a chromosome set (23 chromosomes in humans). In a bisexual animal, the sex cell is either a sperm or an ovum. gametic mortality Form of reproductive isolation in which sperm are immobilized and destroyed before fertilization can take place. gene A section of DNA that has a specific function. gene flow The process in which alleles from one population are introduced into another population. gene pool The sum of all alleles carried by the members of a population. gene therapy A genetic-engineering method in which genetic material is manipulated in ways that include removing, replacing, or altering a gene. generalized species Species that can survive in a variety of ecological niches. genetic counselor A medical professional who advises prospective parents or a person affected by a genetic disease of the probability of having a child with a genetic problem. genetic drift The situation in a small population in which the allelic frequencies of the F1 generation will differ from those of the parental generation due to sampling error. genetic engineering The altering of the genetic material to create specific characteristics in individuals. genetic equilibrium A hypothetical state in which a population is not evolving because the allele frequencies remain constant over time. genetic load The totality of deleterious alleles in a population. genetic sex In humans, male sex is determined by the presence of the Sry gene, which is located on the Y chromosome. Persons who lack the Y chromosome, and hence the Sry gene, or who possess an abnormal allele of the Sry gene, are genetically female. genetics The study of the mechanisms of heredity and biological variation. genome All of the genes carried by a single gamete. genomics The study of the entire genome of a species. genotype The genetic constitution of an individual. genus A group of closely related species. geographical isolation Form of reproductive isolation in which members of a population become separated from another population through geographical barriers that prevent the interchange of genes between the separated populations. geographical race A major division of humankind into large geographical areas wherein people resemble one another more closely than they resemble people in different geographical areas. geomagnetic reversal time scale (GRTS) A chart showing the sequence of normal and reversed polarity of the earth's magnetic field. gestation The period of time from conception to birth. gill arches Skeletal elements supporting the gill slit in nonvertebrate chordates and some vertebrates. gill slits Structures that filter out food particles in nonvertebrate chordates and are used for breathing in some vertebrates. glacial Period of expansion of glacial ice. global warming The rise in the average temperature of the earth's atmosphere and oceans. Gloger's rule Within the same species of mammals, there is a tendency to find more heavily pigmented forms near the equator and lighter forms away from the equator. gluteus maximus In humans, the largest muscle of the human body; acts as an extensor, extending the leg in running and climbing. gluteus medius Muscle of the pelvis that in monkeys and apes acts as an extensor, but in humans acts as an abductor. gluteus minimus Muscle of the pelvis that in monkeys and apes acts as an extensor, but in humans acts as an abductor. gonad General term used for an organ that produces sex cells; the ovary and testis. grammar A set of rules used to make up words and then to combine the words into larger utterances such as phrases and sentences. grandmother hypothesis The idea that the presence of a postmenopausal female in human groups increases the survival rate of children and grandchildren. great apes The orangutan from Asia and the chimpanzee, bonobo, and gorilla from Africa. greenhouse gases Gases that absorb some of the infrared radiation that enters the atmosphere resulting in the heating of the atmosphere and oceans. grooming In primates, the activity of going through the fur with hand or teeth to remove insects, dirt, twigs, dead skin, and so on; also acts as a display of affection. grooming claw A claw found on the second toes of prosimians that functions in grooming. grooming cluster A small group of closely related females that engage in a high degree of grooming. ground running and walking A form of quadrupedalism that takes place on the ground as opposed to in the trees. growth Increase in the size or mass of an organism. growth hormone A hormone produced by the pituitary gland, essential for normal growth. growth plate Narrow zone on a bone where bone growth occurs. guanine One of the bases found in the DNA and RNA molecules; a purine. habitat The place in which a particular organism lives. half-life The time in which one-half of the atoms of a radioactive isotope have decayed. hammerstone A stone that is used to remove flakes from a core by striking the hammerstone against the core. hand ax Large core tool with a sharp cutting edge, blunted at one end so it can be held in the hand. haplorhine primates Primates, such as monkeys, apes, and humans, that lack a rhinarium and possess a free upper lip. haplotype A group or block of nucleotides that tends to be inherited as a unit. hard palate The bony roof of the mouth that separates the mouth from the nasal cavity, permitting the animal to breath and chew at the same time. Hardy-Weinberg equilibrium A mathematical model of genetic equilibrium: p2 + 2pq + q2 = 1. harem A subunit of a larger social group consisting of a male associated with two or more females. heel-toe stride Method of progression characteristic of humans where the heel strikes the ground first; the person pushes off on the big toe. hemochorial placenta Type of placenta found in most anthropoids in which materials pass between the maternal and fetal bloodstreams through a single vessel wall. hemoglobin Red pigment in red blood cells that carries oxygen to and carbon dioxide from body tissues. hemoglobin A (HbA) Normal adult hemoglobin whose globin unit consists of two alpha and two beta chains. hemoglobin A2 (HbA2) A normal variant of hemoglobin A consisting of two alpha and two delta polypeptide chains that is found in small quantities in normal human blood. hemoglobin C An abnormal variant of hemoglobin A that differs from the latter in having a single amino acid substitution on the beta chain at the same position as the substitution producing hemoglobin S. hemoglobin F (HbF) A normal variant of hemoglobin, also known as fetal hemoglobin, that consists of two alpha and two gamma polypeptide chains found in the fetus and early infant; it is gradually replaced by hemoglobin A. hemoglobin S (HbS) An abnormal variant of hemoglobin A that differs from the latter in having a single amino acid substitution on the beta chain; known as sickle hemoglobin. hemolytic disease Disease involving the destruction of blood cells. hemophilia A recessive X-linked trait characterized by excessive bleeding due to a faulty clotting mechanism. herd Among geladas, a large social unit consisting of several bands that come together under very good grazing conditions. heterodont Dentition characterized by regional differentiation of teeth by function. heterozygous Having two different alleles of a particular gene. high-altitude hypoxia Low oxygen pressure due to being at high altitude. high-altitude mountain sickness Includes shortness of breath, physical and mental fatigue, rapid pulse rate, headaches; occurs in persons not acclimatized to high altitudes. higher taxa Taxa above the genus level, such as family, order, class, phylum, and kingdom. hindbrain The posterior of three swellings in the hollow nerve cord of the primitive vertebrate brain formed by a thickening of the wall of the nerve cord. home range The area occupied by an animal or animal group. homeothermic The ability to control body temperature and maintain a high body temperature through physiological means. hominid Member of the family Hominidae; includes all living great apes and humans, plus several extinct forms. hominin Member of the tribe Hominini; includes living humans plus several extinct forms that include, among others, members of the genera Ardipithecus, Australopithecus and Paranthropus. hominine Member of the subfamily Homininae; includes living chimpanzees, bonobos, and humans, plus several extinct forms. hominoid Member of the superfamily Hominoidea; includes living small-bodied apes, great apes, and humans, plus many extinct forms. homodont Situation in which all teeth are basically the same in structure, although they may differ in size, as is found in reptiles. homologous chromosomes Chromosomes of the same pair containing the same genes but not necessarily the same alleles. homology A similarity due to inheritance from a common ancestor. homoplastic Referring to a similarity that is not homologous. Homoplasy can arise from parallelism, convergence, analogy, and chance. homozygous Having two like alleles of a particular gene; homozygous dominant when the allele is dominant and homozygous recessive when the allele is recessive. homozygous dominant Having two dominant alleles of the same gene. homozygous recessive Having two recessive alleles of the same gene. hormones Complex molecules produced by the endocrine glands that regulate many bodily functions and processes. Huntington's disease A degenerative neurological disorder caused by the inheritance of a dominant allele. hybrid Individual that is the result of a cross or mating between two different kinds of parents. hybrid inviability Form of reproductive isolation in which a mating between two species gives rise to a hybrid that is fertile but nevertheless does not leave any offspring. hybrid sterility Form of reproductive isolation in which a hybrid of two species is sterile. hydraulic behavior The transport and dispersal of bones in water. hyperplasia Growth by virtue of increase in the total number of cells resulting from mitosis. hypertrophy Growth by virtue of increase in the size of cells. hyperventilation Increased breathing rate producing a high level of oxygen in the lungs. hypothermia Lowered body temperature induced by cold stress. hypothesis An informed supposition about the relationship of one variable to another. imitative magic A type of magic that is based on the belief that one can affect an actual entity such as a person or animal by manipulating the image of that entity. immutable Unchanging. inclusive fitness An individual's own fitness plus his or her effect on the fitness of any relative. incomplete penetrance The situation in which an allele that is expected to be expressed is not always expressed. independent assortment A Mendelian principle that states that differing traits are inherited independently of each other. It applies only to genes on different chromosomes. index fossil A paleospecies that had a very wide geographical distribution but existed for a relatively short period of time, either becoming extinct or evolving into something else. induced mutation Mutation caused by human-made conditions. Industrial Age A cultural stage characterized by the first use of complex machinery, factories, urbanization, and other economic and general social changes from strictly agricultural societies. industrialism Industrialism is the dependence on mechanization-the use of machines-to produce products and render services. industry All artifacts in a site made from the same material, such as a bone industry. infantile That period in an individual's life cycle from birth to the eruption of the first permanent teeth. insectivore An animal that eats primarily insects; also a member of the mammalian order Insectivora. intelligent design theory An essentially religious explanation of the world that assumes the existence of a supernatural force that is responsible for the great complexity of life on earth today. intensive farming Farming that involves the clearing of a piece of land of all of its natural vegetation and replacing it with one crop that is usually not native to the area. interglacial Period of warming between two glacials. intermediate expression The situation whereby a heterozygous genotype is associated with a phenotype that is more or less intermediate between the phenotypes controlled by the two homozygous genotypes. intermembral index The length of the humerus and radius relative to the length of the femur and tibia. intersexual selection A form of sexual selection; selection for traits that make males more attractive to females. intrasexual selection A form of sexual selection. Selection for characteristics that make males better able to compete with one another for sexual access to females. inversion Form of chromosome aberration in which parts of a chromosome break and reunite in a reversed order. No genetic material is lost or gained, but the positions of the involved alleles are altered. Iron Age A cultural stage characterized by the use of iron as the main metal. irreducible complexity Concept that there are processes and structures that are too complex to have arisen through evolutionary mechanisms but must have arisen by the work of a "designer." ischial callosities A thickening of the skin overlying a posterior section of the pelvis (ischial tuberosity), found in Old World monkeys and some apes. isotopes Atoms of the same element but of different atomic weight. juvenile That period in an individual's life cycle that lasts from the eruption of the first to the eruption of the last permanent teeth. karyotype The standardized classification and arrangement of chromosomes. kin selection A process whereby an individual's genes are selected for by virtue of that individual's increasing the chances that his or her kin's genes are propagated into the next generation. kinetochore Protein structures that form on each side of each centromere in cell division that function in chromosome orientation within the cell. kingdom A major division of living organisms. All organisms are placed into one of five kingdoms: Monera, Protista, Fungi, Planti, and Animalia. Klinefelter syndrome A sex-chromosome count of XXY; phenotypically male, tall stature, sterile. knuckle walking Semierect quadrupedalism, found in chimpanzees and gorillas, with upper parts of the body supported by knuckles as opposed to palms. kwashiorkor A form of protein-caloric malnutrition brought about by a protein-deficient diet that contains a reasonable supply of low-quality carbohydrates. lactation Act of female mammal producing milk. lesser apes See small-bodied apes. lethals Alletes that cause premature death. leukocyte A white blood cell; cell in blood that functions to destroy foreign substances. lexicon In linguistics, the total number of meaningful units (such as words and affixes) of a language. lexigram A symbol that represents a word. life expectancy How long a person, on the average, can expect to live. life span The theoretical genetically determined maximum age. linguistics The scientific study of language. linkage Association of genes on the same chromosome. linkage groups Sets of genes that are found on the same chromosome. lipids Class of compounds that includes fats, oils, and waxes. lithic (stone) industry All artifacts in a site that are made of stone. lithosphere The hard outer layer of the earth. Lower Paleolithic A cultural stage that begins with the manufacture of the first stone tools. lumbar curve A curve that forms in the lumbar region of the spine in humans. macroevolution "Large-scale" evolution; the evolution of new species and higher taxa. macula The central area of the retina consisting of cones only. mammals Members of the class Mammalia, a class of the subphylum Vertebrata, that are characterized by a constant level of activity independent of external temperature and by mammary glands, hair or fur, heterodonty, and other features. mammary glands Glands found in mammalian females that produce milk. mandible The bone of the lower jaw; contains the lower dentition. mandibular torus A thickening of bone on the inside of the mandible. manuport An unmodified, natural rock, brought into a site by human agency, that shows no sign of alteration. marasmus A form of protein-caloric malnutrition caused by a diet deficient in both protein and carbohydrates. marsupial A member of the infraclass Metatheria of the class Mammalia; young are born at a relatively less-developed stage than in placental mammals. After birth, the young attaches to a mammary gland in the pouch, where it continues to grow and develop. masseter A muscle of chewing that arises on the zygomatic arch and inserts on the mandible. maximum parsimony principle The principle that the most accurate phylogenetic tree is one that is based on the fewest changes in the genetic code. mechanical isolation Form of reproductive isolation that occurs because of an incompatibility in structure of the male and female sex organs. meiosis Form of cell division occurring in specialized tissues in the testes and ovaries that leads to the production of gametes or sex cells. melanin Brown-black pigment found in the skin, eyes, and hair. melanocyte Specialized skin cell that produces the pigment melanin. menarche First menstruation. Mesolithic A cultural stage characterized by generalized hunting and gathering and the advent of farming. messenger RNA (mRNA) Form of RNA that copies the DNA code in the nucleus and transports it to the ribosome. metaphase plate During cell division, the central plane of the cell. microenvironment A specific set of physical, biological, and cultural factors immediately surrounding the organism. microevolution "Small-scale" evolution; genetic changes within a population over time. microhabitat A very specific habitat in which a population is found. midbrain The middle of the three swellings in the hollow nerve cord of the primitive vertebrate brain formed by a thickening of the wall of the nerve cord. Middle Paleolithic Refers to the stone tools of the Neandertals and their contemporaries. mitochondria Bodies found in the cytoplasm that convert the energy in the chemical bonds of organic molecules into ATP. mitochondrial DNA (mtDNA) A double-stranded loop of DNA found within the mitochondria; there can be as few as one or as many as a hundred mitochondria per cell, and each mitochondrion possesses between 4 and 10 mtDNA loops. mitosis Form of cell division whereby one-celled organisms divide and whereby body cells divide in growth and replacement. model A representation of a phenomenon on which tests can be conducted and from which predictions can be made. modifying gene A gene that alters the expression of another gene. mold A cavity left in firm sediments by the decayed body of an organism. molecular biology The comparative study of molecules. molecule Unit composed of two or more atoms linked by a chemical bond. monkey Any member of the superfamilies Ceboidea (New World monkeys) and Cercopithecoidea (Old World monkeys). monocausal explanation Attributing one cause to the explanation of a phenomenon. monoculture A field planted with one crop for a long period of time. monogamous pair A social group, found among small-bodied apes and other primates, consisting of a single mated pair and their young offspring. monotreme A member of the subclass Prototheria of the class Mammalia; egg-laying mammal. monozygotic twins Identical twins; derived from a single zygote. morphology The study of structure. motor hypothesis of language A hypothesis that holds that the complicated motor skills needed to manufacture tools lead directly to the motor skills needed to produce speech. mountain sickness See high-altitude sickness. mounting A behavioral pattern whereby one animal jumps on the posterior area of a second animal as a part of the act of copulation or as a part of dominance behavior. Mousterian tradition A Middle Paleolithic cultural tradition associated with the Neandertals, characterized by an increase in the number and variety of flake tools and an ultimate de-emphasis of the hand ax. multimale group A social unit consisting of many adult males and adult females. multiple alleles A situation in which a gene has more than two alleles. mutagens Factors-such as radioactivity, chemicals, and viruses-that are capable of causing mutations. mutation An alteration of the genetic material. natural selection Differential fertility and mortality of variants within a population. negative eugenics Method of eliminating deleterious alleles from the gene pool by encouraging persons with such alleles not to reproduce. neocortex Gray covering on the cerebrum of some vertebrates; site of higher mental processes. Neolithic A cultural stage marked by established farming. New World semibrachiation Locomotor pattern involving extensive use of hands and prehensile tail to suspend and propel the body in species otherwise quadrupedal. niche See ecological niche. nocturnal Active at night. nondisjunction An error of meiosis in which the members of a pair of chromosomes move to the same pole rather than moving to opposite poles. notochord A cartilaginous rod that runs along the back (dorsal) of all chordates at some point in their life cycle. nuchal crest Flange of bone in the occipital region of the skull that serves as the attachment of the nuchal musculature of the back of the neck. nuchal muscle The muscle in the back of the neck that functions to hold the head up. In primates with heavy facial skeletons, the large nuchal muscle attaches to a nuchal crest. nuclear DNA (nDNA) DNA found within the nucleus of the cell. nuclear membrane A structure that binds the nucleus within the cell. nucleic acids The largest of the molecules found in living organisms; they are composed of chains of nucleotides. nucleotide The basic building block of nucleic acids; a nucleotide is composed of a five-carbon sugar (either ribose or deoxyribose), a phosphate, and a base. nucleus A structure found in the cell that contains the chromosomes. occipital condyles Two rounded projections on either side of the foramen magnum that fit into a pair of sockets on the top of the spine, thus articulating the skull with the spine. occipital torus A horizontal bar of bone seen above the angularity in the occipital. Old World semibrachiation Locomotor pattern involving extensive use of hands, but not the tail, in leaping in a basically quadrupedal animal. olfactory Referring to the sense of smell. omnivorous Eating both meat and vegetable food. one-male group A social unit consisting of a single male associated with several females. oogenesis The production of ova. openness A characteristic of language that refers to the expansionary nature of language, which enables people to coin new labels for new concepts and objects. opposable thumb Anatomical arrangement in which the fleshy tip of the thumb can touch the fleshy tip of all the fingers. order Major division of a class, consisting of closely related families. orthognathous Describes a face that is relatively vertical as opposed to being prognathous. orthograde Vertical posture. ossification Process of bone formation. osteodontokeratic culture An archaeological culture based on tools made of bone, teeth, and horn. osteology The study of bones. outgroup Species used in a cladistic analysis that are closely related to the species being studied and are used to differentiate between shared derived and ancestral derived features. ovulation The point during the female reproductive cycle, usually the midpoint, when the ovum has matured and breaks through the wall of the ovary. ovum A female gamete or sex cell. ozone A molecule composed of three oxygen atoms (O3). Atmospheric ozone shields organisms from excessive ultraviolet radiation. paleoanthropology Scientific study of fossils and artifacts and the context in which they are found. paleoecology The study of the relationship of extinct organisms or groups of organisms to their environments. Paleolithic A type of culture called the "Old Stone Age." paleontology The study of fossils. paleopathology The study of injuries and disease in prehistoric populations. paleospecies A group of similar fossils whose range of morphological variation does not exceed the range of variation of a closely related living species. palynology The study of fossil pollen. pangenesis An early and inaccurate idea that acquired characteristics of the parents are transmitted to their offspring. parallelism Homoplastic similarities found in related species that did not exist in the common ancestor; however, the common ancestor provided initial commonalities that gave direction to the evolution of the similarities. partial pressure The pressure exerted by a particular gas in the atmosphere. pedigree A reconstruction of past mating in a family, expressed as a diagram. penetrance The degree to which an allele is expressed in the phenotype. pentadactylism Possessing five digits on the hand and/or foot. peptide bond A link between amino acids in a protein. pericentric inversion A type of inversion whereby two breaks occur in a chromosome, one on either side of the centromere, and the centerpiece becomes turned around and rejoined with the two outside pieces. period A unit of geological time; a division of an era. peripheralization Process whereby an adolescent animal encounters aggressive behavior from adults and gradually moves away from the group. permanent teeth The second set of teeth that erupts in mammals; humans have 32 permanent teeth. phenotype The observable and measurable characteristics of an organism. phenotypic sex The sex that a person is judged to be, based on his or her physical appearance. Phenotypic sex may not correspond to chromosomal sex. phenylketonuria (PKU) A genetic disease, inherited as a recessive, brought about by the absence of the enzyme responsible for the conversion of the amino acid phenylalanine to tyrosine; phenylalanine accumulates in the blood and then breaks down into by-products that cause severe mental retardation in addition to other symptoms. phenylthiocarbamide (PTC) An artificially created substance whose main use is in detecting the ability to taste it; ability to taste PTC is inherited as a dominant. philtrum A furrow in the upper lip that serves to attach the upper lip to the gum. phosphate unit A unit of the nucleic acid molecule consisting of a phosphate and four oxygen atoms. phyletic gradualism The idea that evolution is a slow process with gradual transformation of one population into another. phylogenetic tree A graphic representation of evolutionary relationships among species. phylogeny The evolutionary history of a population or taxon. phylum Major division of a kingdom, consisting of closely related classes; represents a basic body plan. physical anthropology A branch of anthropology concerned with human biology and evolution. physical environment The inanimate elements that surround an organism. phytoliths Microscopic pieces of silica that form within plants; the distinctive shapes of phytoliths found in different plants permit their identification when observed imbedded in fossil teeth. placenta An organ that develops from fetal membranes that functions to pass oxygen, nutrients, and other substances to and waste material from the fetus. placental mammal A member of the infraclass Eutheria of the class Mammalia; mammals that form a placenta. plasma membrane A structure that binds the cell but allows for the entry and exit of certain substances. plate tectonics The theory that the surface of the earth is divided into a number of plates that move in relationship to each other. Some of these plates carry the continents. platycephalic Having a low, relatively flat forehead. platyrrhine nose Nose in which nostrils open sideways and are usually separated by a broad nasal septum; characteristic of the New World monkeys. play Energetic and repetitive activity engaged in primarily by infants and juveniles. play group A group of juveniles within a larger social unit that engage in play behavior. pleiotropy Situation in which a single allele may affect an entire series of traits. pneumatized The presence of air spaces within some bones of the skull. point mutation An error at a particular point on the DNA molecule. polar body A cell that develops in oogenesis that contains little cytoplasm and does not develop into a mature ovum. polyandrous group A form of social organization found in primates in which a female has multiple mates. polygenic The result of the interaction of several genes. polymorphism The presence of several distinct forms of a gene or phenotypical trait within a population with frequencies greater than 1 percent. polypeptide Chain of amino acids. polyphyodonty The continuous replacement of teeth such as found in reptiles. population bottlenecking A form of sampling error in which a population is reduced in size, which in turn reduces variability in the population. The population that descends from the reduced population is therefore less variable than the original population. populationist viewpoint The viewpoint that only individuals have reality and that the type is illusory; since no two individuals are exactly alike, variation underlies all existence. porphyria A dominant genetic abnormality that results from a defect in the breakdown of hemoglobin in the blood. Symptoms include sensitivity to sunlight and the development of psychiatric symptoms. positive eugenics Method of increasing the frequency of desirable traits by encouraging reproduction by individuals with these traits. postmating mechanism Any form of reproductive isolation that occurs after mating. postorbital bar A feature of the skull formed by an upward extension of the zygomatic arch and a downward extension of the frontal bone that supports the eye. postorbital constriction As seen from a top view, a marked constriction in the skull immediately behind the orbits and brow ridge. postorbital septum A bony partition behind the eye that isolates the eye from the muscles of the jaw and forms a bony eye socket or orbit in which the eye lies. potassium-argon dating Chronometric dating technique based on the rate of decay of potassium 40 to argon 40. power grip A grip in which an object is held between the fingers and the palm with the thumb reinforcing the fingers. preadaptation The situation in which a new structure or behavior that evolved in one niche is by chance also suited, in some cases better suited, to a new niche. precision grip A grip in which an object is held between one or more fingers with the thumb fully opposed to the fingertips. predation model A model that give an explanation of why primates form groups based on the hypothesis that a group of individuals can protect themselves better or even ward off attacks from predators better than an individual animal could. prehensile tail A tail found in some New World monkeys that has the ability to grasp. premating mechanism A form of reproductive isolation that prevents mating from occurring. prenatal That period of an individual's life cycle from conception to birth. presenting A behavior involving a subordinate primate showing his or her anal region to a dominant animal. preservation potential The probability of a bone being preserved after death. primary center of ossification Area of first appearance of bone within the cartilage model of a long bone. primatology The study of primates. principle of acquired characteristics Concept, popularized by Lamarck, that traits gained during a lifetime can then be passed on to the next generation by genetic means; considered invalid today. principle of use and disuse Concept popularized by Lamarck that proposes that parts of the body that are used are often strengthened and improved, whereas parts of the body that are not used become weak and ultimately may disappear. prognathism A jutting forward of the facial skeleton and jaws. pronograde Posture with the body held parallel to the ground. prosimians Members of the suborder Prosimii; includes the lemuriforms and tarsiiforms. proteins Long chains of amino acids joined together by peptide bonds (a polypeptide chain). protein-caloric malnutrition A class of malnutrition that includes kwashiorkor and marasmus. protoculture The simplest or beginning aspects of culture as seen in some nonhuman primates. prototherian Referring to mammals belonging to the subclass Prototheria; a monotreme or egg-laying mammal. provisioned colony Group of free-ranging primates that have become accustomed to humans because of the establishment of feeding stations. puberty An event in the life cycle that includes a rapid increase in stature, development of sex organs, and the development of secondary sexual characteristics. pubic symphysis The area of the pelvis at which the two innominates join. punctuated equilibrium A model of evolution characterized by an uneven tempo of change. purine Base found in nucleic acids that consists of two connected rings of carbon and nitrogen; in DNA and RNA, adenine and guanine. pyrimidine Base found in nucleic acids that consists of a single ring of carbon and nitrogen; in DNA, thymine and cytosine; in RNA, uracil and cytosine. quadrumanous Locomotor pattern found among orangutans, who often suspend themselves under branches and move slowly using both forelimbs and hindlimbs. quadrupedalism Locomotion using four limbs, with hands and feet moving on a surface such as the ground or top of a branch of a tree. race A taxonomic division of a species that differs biologically in a significant number of genetic characteristics from other races of the same species. radiation Electromagnetic energy that is given off by an object. radioactivity The phenomenon whereby an atom that is unstable will radioactively decay into another type of atom and in the process emit energy and/or particles. radiocarbon dating A method of chronometric dating based on the decay of carbon 14. radiometric dating techniques Chronometric dating methods based on the decay of radioactive materials; examples are radiocarbon and potassium-argon dating. range See home range. recessive An allele that is expressed only in the homozygous recessive condition. recombination New combinations of alleles on the same chromosome as a result of crossing-over. recursion The process by which any linguistic unit can be made longer by embedding another unit in it. regional continuity model The hypothesis that states that modern H. sapiens had multiple origins from existing local populations; each local population of archaic humans gave rise to a population of modern H. sapiens. regulatory gene A segment of DNA that functions to initiate or block the function of another gene. relative dating Any dating technique that places two fossils or artifacts in time relative to one another, where one is older than, younger than, or the same age as the other. replacement model The hypothesis that states that modern H. sapiens evolved in Africa and radiated out of this area, replacing archaic hominin populations. reproductive isolating mechanism A mechanism that prevents reproduction from occurring between two populations. reproductive population A group of organisms capable of successful reproduction. residual volume The amount of air remaining in the lungs after the most forceful expiration. resource-defense model A model that gives an explanation of why primates form groups based on the hypothesis that a group of individuals can defend access to resources such as food and keep other animals and other groups away from those resources better than an individual can. restriction enzyme Enzyme used to "cut" the DNA molecule at specific sites; used in recombinant DNA technology. retina The layer of cells in the back of the eye that contains the cells-rods and cones-that are sensitive to light. retouch Further refinement in the manufacture of stone tools by the removal of additional small flakes. Rh blood-type system A blood-type system consisting of two major alleles. A mating between an Rh2 mother and Rh1 father may produce in the infant the hemolytic disease erythroblastosis fetalis. rhinarium The moist, naked area surrounding the nostrils in most mammals; present in the lemuriforms. ribonucleic acid (RNA) A type of nucleic acid based on the sugar ribose; exists in cells as messenger RNA and transfer RNA. ribose A five-carbon sugar found in RNA. ribosome Small spherical body within the cytoplasm of the cell in which protein synthesis takes place. rickets A bone disease that usually is caused by a lack of calcium, phosphate, or vitamin D. rods Cells of the retina of the eye that are sensitive to the presence or absence of light; function in black-and-white vision. sagittal crest Ridge of bone along the midline of the top of the skull that serves for the attachment of the temporalis muscle. sagittal keel A bony ridge formed by a thickening of bone along the top of the skull; characteristic of H. erectus. sampling error In population genetics, the transmission of a nonrepresentative sample of the gene pool over space or time due to chance. scent marking Marking territory by urinating or defecating, or by rubbing scent glands against trees or other objects. science A way of learning about the world by applying the principles of scientific thinking, which includes making empirical observations, proposing hypotheses to explain those observations, and testing those hypotheses in valid and reliable ways; also refers to the organized body of knowledge that results from scientific study. scraper A tool manufactured from a flake with a scraping edge on the end or side. seasonal isolation Form of reproductive isolation in which the breeding seasons of two closely related populations do not exactly correspond. secondary center of ossification Area of bone development, usually near the end of a long bone. secondary sexual characteristic Physical feature other than the genitalia that distinguishes males from females after puberty. secreter allele A dominant allele of the secretor gene. People who inherit this allele secrete blood type antigens into their body fluids such as semen, saliva, tears, and mucus. sectorial premolar Unicuspid first lower premolar with a shearing edge. secular trend The tendency over the last hundred or so years for each succeeding generation to mature earlier and become, on the average, larger. sediment Material that is suspended in water; in still water, it will settle at the bottom. sedimentary beds Beds or layers of sediments called strata. sedimentation The accumulation of geological or organic material deposited by air, water, or ice. segregation In the formation of sex cells, the process in which paired hereditary factors separate, forming sex cells that contain either one or the other factor. selective agent Any factor that brings about differences in fertility and mortality. selective pressure Pressure placed by a selective agent on certain individuals within the population that results in the change of allelic frequencies in the next generation. semibrachiation A form of quadrupedalism in which an animal makes extensive use of its forelimbs to suspend itself under branches in order to reach food below. sex chromosomes The X and Y chromosomes. Males usually have one X and one Y chromosome; females usually have two X chromosomes. sex-controlled trait Non-sex-linked trait that is expressed differently in males and females. sex-limited gene Non-sex-linked allele that is expressed in only one of the sexes. sex-limited trait Non-sex-linked trait that is expressed in only one of the sexes. sexual dimorphism Differences in structure between males and females of the same species. sexual isolation Form of reproductive isolation in which one or both sexes of a species initiate mating behavior that does not act as a stimulus to the opposite sex of a closely related species. sexual selection Selection that favors characteristics that increase reproductive success, usually due to male competition or female mate choice. sexual skin Found in the female of some primate species; skin in anal region that turns bright pink or red and may swell when animal is in estrus. shared ancestral (symplesiomorphic) feature Compared with shared derived features, a homology that did not appear as recently and is therefore shared by a larger group of species. shared derived (synapomorphic) feature A recently appearing homology that is shared by a relatively small group of closely related taxa. sharing cluster Among chimpanzees, a temporary group that forms after hunting to eat the meat. shell midden A large mound composed of shells, which provides evidence of the emphasis on shellfish as a food resource. shovel-shaped incisors Incisors that have a scooped-out shape on the tongue side of the tooth. sickle-cell anemia Disorder in individuals homozygous for hemoglobin S in which red blood cells will develop into a sickle shape, which, in turn, will clog capillaries, resulting in anemia, heart failure, and so on. sickle-cell trait The condition of being heterozygous for hemoglobin A and S, yet the individual usually shows no abnormal symptoms. simian shelf A bony buttress on the inner surface of the foremost part of the ape mandible, functioning to reinforce the mandible. single-crystal fusion A form of potassium-argon dating that uses a laser to melt individual crystals to release the argon. site A location where artifacts are found. slow climbing A form of quadrupedalism in which the animal moves very slowly through brushes and trees. small-bodied (lesser) apes The gibbons and simiangs of Asia. The primate family Hylobatidae, which includes the gibbons and is a diverse group consisting of 13 species placed into four genera. smoke-detector principle A defense mechanism that is so fine tuned that even an insignificant stimulus might trigger it. social Darwinism The application of the principles of biological evolutionary theory to an analysis of social phenomena. social intelligence The knowledge and images that originates in an individual's brain that are transferred by speech, sign language, and in the last 5000 years, writing, to the brains of others. specialized species A species closely fitted to a specific niche and able to tolerate little change in that niche. speciation An evolutionary process that is said to occur when two previous subspecies (of the same species) are no longer capable of successful interbreeding; they are then two different species. species The largest natural population whose members are able to reproduce successfully among themselves but not with members of other species. sperm Male gamete or sex cell. spermatids Cells produced by meiosis in the male that are transformed into mature sperm. spermatogenesis Sperm production. spindle Structure that appears in the cell undergoing cell division that is responsible for the movement of the chromosomes. spontaneous generation An old and incorrect idea that complex life forms could be spontaneously created from nonliving material. spontaneous mutation Mutation that occurs spontaneously, that is, in response to the usual conditions within the body or environment. stabilizing selection A type of natural selection characterized by a generation-after-generation shift in a population in the direction of the average (mean) individual, such as, for example, toward average body size. In this example, individuals with small and large body size are being selected against. standard deviation A statistical measurement of the amount of variation in a series of determinations; the probability of the real number falling within plus or minus one standard deviation is 67 percent. stereoscopic vision Visual perception of depth due to overlapping visual fields and various neurological features. strata Layers of sedimentary rocks. stratigraphy The investigation of the composition of the layers of the earth, used in relative dating; based on the principle of superposition. stratosphere That part of the atmosphere 20 to 50 kilometers (12 to 31 miles) above the earth's surface where ozone forms. strepsirhine primates Primates, such as lemurs and lorises, that possess a rhinarium and philtrum. structural gene A segment of DNA that codes for a polypeptide that has a phenotypic expression. subchron A small subdivision within a chron. subcutaneous fat The fat deposited under the skin. subera A division of an era. The Cenozoic is divided into two suberas: the Tertiary and the Quaternary. subspecies Interfertile groups within a species that display significant differentiation among themselves. superposition Principle that under stable conditions, strata on the bottom of a deposit were laid down first and hence are older than layers on top. suspensory behavior Form of locomotion and posture whereby animals suspend themselves underneath a branch. sweating The production of a fluid, sweat, by the sweat glands of the skin; the evaporation of the sweat from the skin leads to a cooling of the body. symbol Something that can represent something distant from it in time and space. sympatric species Different species living in the same area but prevented from successfully reproducing by a reproductive isolating mechanism. symphyseal face The surface of the pubis where one pubis joins the other at the pubic symphysis. symplesiomorphic feature See shared ancestral feature. synapomorphic feature See shared derived feature. synthetic theory of evolution The theory of evolution that fuses Darwin's concept of natural selection with information from the fields of genetics, mathematics, embryology, paleontology, animal behavior, and other disciplines. system A collection of parts that are interrelated so that a change in any one part brings about specifiable changes in the others. tactile pads The tips of the fingers and toes of primates; areas richly endowed by tactile nerve endings sensitive to touch. taphonomy The study of the processes of burial and fossilization. taxon A group of organisms at any level of the taxonomic hierarchy. The major taxa are the species and genus and the higher taxa: family, order, class, phylum, and kingdom. taxonomy The science of classifying organisms into categories. Tay-Sachs disease Enzyme deficiency of lipid metabolism inherited as a recessive; causes death in early childhood. tectonic plate A segment of the lithosphere. temporal-nuchal crest A crest on the back of the skull, forming on the occipital and temporal bones. temporalis A muscle of chewing that arises on the side of the skull and inserts on the jaw. temporomandibular joint The joint formed at the point of articulation of the mandible and the base of the skull. termite stick Tool made and used by chimpanzees for collecting termites for food. territory The area that a group defends against other members of its own species. testosterone A male sex hormone. thalassemia Absence or reduction of alpha- or beta-chain synthesis in hemoglobin; in the homozygous condition (thalassemia major), a high frequency of hemoglobin F and fatal anemia occurs; in the heterozygous condition (thalassemia minor), it is highly variable but usually occurs with mild symptoms. theory A step in the scientific method in which a statement is generated on the basis of highly confirmed hypotheses and used to generalize about conditions not yet tested. therian Referring to mammals belonging to the subclass Theria; the "live-bearing" mammals including the marsupials and placental mammals. thermoluminescence dating A chronometric dating method based on the fact that when some materials are heated, they give off a flash of light. The intensity of the light is proportional to the amount of radiation to which the sample has been exposed and the length of time since the sample was heated. threat gesture A physical activity that serves to threaten another animal. Some threat gestures are staring, shaking a branch, and lunging toward another animal. thymine One of the bases found in DNA; a pyrimidine. tool An object that appears to have been used for a specific purpose. total color blindness See achromatopsia. trait One aspect of the phenotype. transfer RNA (tRNA) Within the ribosome, a form of RNA that transports amino acids into the positions coded in the mRNA. translocation Form of chromosomal mutation in which segments of chromosomes become detached and reunite to other nonhomologous chromosomes. tree-ring dating Chronometric dating method that determines the age of a wood sample by counting the number of annual growth rings. trichromacy The possession of three visual pigments, sensitive to blue, green, and red, in the retina of the eye. trisomy The state of having three of the same chromosome, rather than the normal pair. For example, trisomy 21, or Down syndrome, is a tripling of chromosome number 21. troop A multimale group found among baboons and other primates. true brachiation Hand-over-hand locomotion along a branch with the body suspended underneath the branch by the arms. true-breeding Showing the same traits without exception over many generations. tuff Geological formation composed of compressed volcanic ash. tundra A type of landscape where the ground is frozen solid throughout most of the year but thaws slightly during the summer. Turner syndrome Genetic disease characterized by 45 chromosomes with a sex chromosome count of X-; phenotypically female, but sterile. twin studies Comparisons of monozygotic twins to dizygotic twins for the purpose of estimating the degree of environmental versus genetic influence operating on a specific trait. tympanic membrane The eardrum. typological The viewpoint that basic variation of a type is illusory and that only fixed ideal types are real; two fossils that differ from each other in certain respects represent two types and, hence, are two different species. unconformity The surface of a stratum that represents a break in the stratigraphic sequence. uniformitarianism Principle that states that physical forces working today to alter the earth were also in force and working in the same way in former times. uniquely derived feature See autapomorphic feature. Upper Paleolithic Refers to the stone tools of anatomically modern peoples. uracil One of the bases found in RNA; a pyrimidine. urbanization A rise in the number of people living in cities in comparison to the number living in rural areas. urbanized society A society in which a majority of the population lives in cities. utilized material Pieces of stone that have been used without modification. variable Any property that may be displayed in different values. vasoconstriction Constriction of the capillaries in the skin in response to cold temperatures that prevents much of the warm blood from reaching the surface of the body where heat could be lost. vasodilation Opening up of the capillaries of the skin in response to warm temperatures, increasing the flow of blood to the surface of the body and thereby increasing the loss of body heat. velocity curve A curve that illustrates the velocity or rate of growth over time by plotting the degree of growth per unit of time. ventral The front or bottom side of an animal. Venus figurines Small Upper Paleolithic statues characterized by exaggerated breasts and buttocks and very stylized heads, hands, and feet. vertebrate A member of the subphylum Vertebrata; possesses a bony spine or vertebral column. vertical clinging and leaping A method of locomotion in which the animal clings vertically to a branch and moves between branches by leaping vertically from one to another. The animal moves on the ground by hopping or moves bipedally. X chromosome The larger of the two sex chromosomes. Females usually possess two X chromosomes; males usually possess one X and one Y chromosome. X-linked Refers to genes on the X chromosome. Y chromosome The smaller of the two sex chromosomes. Females usually possess no Y chromosome; males usually possess one X and one Y chromosome. Y-5 pattern Pattern found on molars with five cusps separated by grooves, reminiscent of the letter Y. Y-linked Refers to genes on the Y chromosome. zoonoses Infectious diseases that are transmitted to humans from animals. zygomatic arch The "cheek" bone; an arch of bone on the side of the skull. zygote A fertilized ovum. zygotic mortality Form of reproductive isolation in which fertilization occurs but development stops soon after. zymotics Infectious diseases that spread easily from person to person in crowded areas.   Glossary of Primate Higher Taxa Extinct taxa are indicated by a †. Adapidae† Family of Eocene prosimians found in North America, Asia, Europe, and possibly Africa; may be related to lemurs and lorises. Adapinae† Subfamily of the Adapidae found in Europe and Asia. Alouattinae Subfamily of the Cebidae; includes the howler monkeys. Anthropoidea Suborder of the order Primates; includes the New World monkeys, Old World monkeys, apes, and humans. Aotinae Subfamily of the Cebidae; includes the owl monkeys. Callitrichidae A family of New World monkeys consisting of the marmosets and tamarins. Catarrhini Infraorder of the suborder Anthropoidea that includes the superorders Cercopithecoidea and Hominoidea. Cebidae A family of New World monkeys that includes the squirrel, spider, howler, and capuchin monkeys, among others. Cebinae Subfamily of the Cebidae; includes the capuchin and squirrel monkeys. Ceboidea A superfamily of the suborder Anthropoidea; includes all the New World monkeys, consisting of the families Callitrichidae and Cebidae. Cercopithecidae Family of the superfamily Cercopithecoidea; includes the Old World monkeys. Cercopithecinae Subfamily of the family Cercopithecidae; includes the Old World monkeys that are omnivorous and possess cheek pouches, such as the macaques, baboons, guenons, and mangabeys. Cercopithecoidea Superfamily of the suborder Anthropoidea; consists of the Old World monkeys. Colobinae A subfamily of family Cercopithecidae; the Old World monkeys that are specialized leaf eaters, possessing a complex stomach and lacking cheek pouches, such as the langurs and colobus monkeys. Daubentoniidae Family of Madagascar prosimians consisting of the aye-aye. Gorillini Tribe of the subfamily Homininae that includes the gorillas, chimpanzees, and bonobos. Hominidae Family of the superfamily Hominoidea that includes organutans, gorillas, chimpanzees, bonobos, and humans. Homininae Subfamily of the family Hominidae that includes the African great apes and humans. Hominini Tribe of the subfamily Homininae that includes humans. Hominoidea Superfamily of the suborder Anthropoidea; includes the apes and humans. Hylobatidae Family of the superfamily Hominoidea; the lesser apes consisting of the gibbons and siamang. Indriidae Family of Madagascar prosimians that includes the indri, sifaka, and avahi. Lemuridae Madagascar lemuriforms; includes the lemurs. Lemuriformes Infraorder of the suborder Prosimii that includes the lemurs, indris, and aye-aye of Madagascar and the lorises, potto, angwantibo, and galago. Lorisidae lemuriforms; includes the loris, potto, angwantibo, and galago. Omomyidae† Family of Eocene and Oligocene primates, showing some resemblance to the tarsiers, found in North America, Europe, Asia, and Africa. Parapithecidae† Family of the order Primates consisting of Early Oligocene primates from the Fayum, Egypt. Parapithecoidea† Suborder of the order Primates that contains the family Parapithecidae. Pithecinae Subfamily of the Cebidae; includes the titis, sakis, and uakaris. Platyrrhini Infraorder of the suborder Anthropoidea that includes the New World monkeys and various New World fossil taxa. Plesiadapiformes† Group of Paleocene fossil mammals that are thought by some paleontologists to be among the earliest members of the Primate order. Ponginae Subfamily of the family Hominidae that includes the organutans of southeast Asia. Primates Order of the class Mammalia that includes the living prosimians, tarsiers, New World monkeys, Old World monkeys, lesser apes, great apes, and humans. Proconsulidae† Family of miocene hominoids from Africa. Propliopithecidae† Family of the infraorder Catarrhini from the Middle Oligocene to Late Miocene of Africa and Europe; may have given rise to the Old World monkeys and the hominoids. Prosimii Suborder of the order Primates that includes the lemurs, indris, and aye-aye of Madagascar and the lorises, potto, angwantibo, galagos, and tarsiers of Africa and Asia. Tarsiiformes Infraorder of the suborder Prosimii that includes the tarsiers of southeast Asia. Victoriapithecidae† Family of Early and Middle Miocene Old World monkeys from north and east Africa.
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