Barzilai, Nir, et. al. October 15, 2003. Unique lipoprotein phenotype and genotype associated with exceptional longevity. The Journal of the American Medical Association 290:2030–40. The right cholesterol-carrier profile can add 20 years to life.

Cibelli, Jose B., et al. January 2002. The first human cloned embryo. Scientific American 286(1):44–51. It was only a few cells, but it caused a flutter of headlines.

Couzin, Jennifer. March 12, 2004. Textbook rewrite? Adult mammals may produce eggs after all. Science 303:1593. mice make eggs through maturity. Do humans?

Friedrich, M. J. November 13, 2002. Biological secrets of exceptional old age. The Journal of the American Medical Association 288(18):2247–53. Researchers are discovering the parts of the genome that control life span in people past the age of 100 and their families.

Hayflick, Leonard. January 27, 2000. New approaches to old age. Nature 403:365. We live longer than our genes dictate.

Hwang, Woo Suk, et al. March 12, 2004. Evidence of a pluripotent human embryonic stem cell line derived from a cloned blastocyst. Science 303:1669-1764. Somatic cell nuclear transfer is possible in humans, but is very difficult to achieve.

Kipling, David, et al. September 3, 2004. What can progeroid syndromes tell us about human aging? Science 305:1593. the progeroid disorders may represent accelerating aging.

Lewis, Ricki. March 24, 2003. Porcine parts on the horizon? The Scientist 17(6):7. Cloned pigs whose cells lack molecules that stimulate the human immune system may one day provide organs.

Lewis, R. October 30, 2000. New light on fetal origins of adult disease. The Scientist 14(21):1. Starvation during prenatal development can alter gene expression in ways that raise the risks of developing certain multifactorial disorders in adulthood.

O'Connor, Anahad. March 25, 2003. Images of preserved embryos to become a learning tool. The New York Times, p. F1. The Virtual Human Embryo has images of miscarried embryos.

Perls, Thomas T., et al. June 11, 2002. Life-long sustained mortality advantage of siblings of centenarians. Proceedings of the National Academy of Sciences 99(12):8442–47. Siblings of people past the age of 100 also lead longer lives, indicating that genes contribute to longevity.

Puca, Annibale, et al. August 28, 2001. A genomewide scan for linkage to human exceptional longevity identifies a locus on chromosome 4. Proceedings of the National Academy of Sciences 98:10505–08. Comparing long-lived siblings revealed that part of chromosome 4 includes genes involved in life span.

Shermer, Michael. April 2003. I, clone. Scientific American. 288(4):38. Why a clone is not an exact duplicate.

Spitz, Lewis, and Edward M. Kiely. March 12, 2003. Conjoined twins. The Journal of the American Medical Association 289(10):1307–10. There are different types of conjoined twins.

The December 18, 2001 issue of The New York Times, section F, has several articles and spectacular illustrations and photos of human prenatal development.