Content provided in partnership with

Human Origins: What Bones and Genomes Tell Us About Ourselves

Natural History, April, 2008 by Laurence A. Marschall

[ILLUSTRATION OMITTED]

by Rob DeSalle and Ian Tattersall

Texas A&M University Press, 2008; $29.95

Most Popular Articles in Reference: The importance of understanding organizational culture; Credit card attitudes and behaviors of college students; What factors attract foreign direct investment?; Libraries Need Relationship Marketing - mutual interest marketing concept, ...; How to set performance goals: employee reviews are more than annual critiques; More »

Mention the search for human origins to an intelligent layperson and you most likely evoke the image of a khaki-clad paleontologist, in the mold of Richard Leakey, scrabbling for bones in an African landscape. Great progress in tracing out the human family tree has indeed been made in this fashion, but over the last few decades remarkable advances in several disciplines--molecular biology and genetics most of all--have revolutionized the way we regard the human past. The conventional wisdom of paleoanthropology has been sometimes challenged, sometimes supported, and most often sharpened by the precision of the new molecular techniques. Appropriately, the American Museum of Natural History (AMNH) recently decided that it was time to mount a new permanent exhibition on human origins, incorporating diverse fields of study. The exhibit's companion book, written by geneticist Rob DeSalle and paleoanthropologist Ian Tattersall, both on the museum's staff, is an accessible and authoritative summary of the major insights of the new synthesis.

Molecular biology has, first of all, made it possible to refine our understanding of the relationships among species, living and extinct. Relying on fossils alone was always a chancy enterprise. Nowadays we can look at similarities in sequences of DNA to trace out the details of animal family trees, often with unanticipated results that challenge commonsense conclusions based solely on appearance. Whales turn out to be the closest kin of hippos; mushrooms are more closely related to armadillos than they are to oak trees; and, closer to us, primates seem to be second cousins to bats and tree shrews.

It's not just living animals whose DNA is accessible, either. Genomic detectives are beginning to sequence the mitochondrial genome of Homo neanderthalensis, using shavings from fossils, and it already seems clear to the authors that those hominids never interbred with Cro-Magnons, Homo sapiens, though they coexisted. The disappearance of Neanderthals can't be attributed to intermarriage, then; it seems increasingly likely that they were wiped out, not assimilated, by the Cro-Magnons.

Now that DNA analysis has become cheaper, faster, and better understood, it's even possible to compare the coding sequences of large populations of individuals. That enables scientists to trace routes of human migration back into the past by looking for certain "marker" genes, which are passed on, virtually unaltered, from parent to child. The similarity in genes between natives of central Siberia and natives of South America, for instance, pretty much squelches Thor Heyerdahl's KonTiki theory that the first Americans came on rafts across the Pacific, and supports the view that they walked across an isthmus or an ice bridge that once spanned today's Bering Strait.

Molecular biology may even shed light on perhaps the greatest puzzle of human origins: how our ancestors leaped the gap separating smart apes from Homo sapiens. How did we become creatures with the ability to think in symbols, to use language, and to create works dart, music, and literature? If you share the optimism of the authors, the answer will come from identifying the genes that give us the ability to distinguish color, to perceive changes in pitch, to memorize and calculate, and a host of other faculties, some of which we are not yet even aware we possess. Granting the remarkable advances we're already making, it's not clear whether genetic reductionism will ultimately unravel the deeper meaning of our unique form of consciousness. Readers of this book and viewers of the new AMNH hall may marvel at how much we've learned about the human past in the last few decades, yet wonder still at what it means to be human.

LAURENCE A. MARSCHALL is W.K.T. Sahm Professor of Physics at Gettysburg College in Pennsylvania, and director of Project CLEA, which produces widely used simulation software for education in astronomy.

Human Origins: What Bones and Genomes Tell Us About Ourselves

Natural History, April, 2008 by Laurence A. Marschall

Find Research Guides for:

Find Featured Titles for: Technology

Most Popular Articles in Reference

Most Popular Publications in Reference