Becoming Human

A new dating method indicates the stone tools found at Zhoukoudian in China are considerably older than first believed, according to a paper published in the journal Nature this week.  Zhoukoudian, not far from Beijing, then called Peking in the West, is the site of a cave first excavated by Franz Weidenreich starting in the late Twenties and during the decade of the Thirties.  Fossili

Human footprints, whether encountered on a beach or after the snow has stopped falling, have an effable quality.  Bones and human artifacts, after examination by specialists, can tell us much about how life was lived in earlier times but footprints are full of wonder for us.  They may have been made yesterday or, as occurs so rarely, a million years ago and we feel a connection with the unknown

In our occasional series, How Science Is Done, we attempt to show how real scientists, working on real questions, find answers - if not final answers, then suggestive answers that expand our knowledge into hitherto murky areas.

"Lucy" is the three million year old fossil discovered in the Afar region of Ethiopia in 1974 by Don Johanson. For more than three decades this remarkable find, which has told us so much about out origins, has been the subject of controversy.

Science is done in many ways.

A trail of footprints left in volcanic ash nearly four million years ago, corroborating the contention that Lucy was a biped, is threatened by both man made and natural damage in Tanzania, it was declared recently at a scientific symposium in South Korea.

By examining patterns of DNA variation in the genome for different human populations, we can determine how much of our evolutionary history was influenced by simple demographic change or, alternatively, by spurts of natural selection.

Teaser: Human offspring take more than twice the time to reach adulthood than do our closest living relatives, chimps and gorillas. This period of delayed maturation results in what we call the teenage years and is a characteristic of modern humans. Paleoanthropologists wonder how far back in the record of bipedal existence this delayed maturation commenced.

Dr Gary Schwartz, professor of paleoanthropology at the Institute of Human Origins, Arizona State University, is researching fossil teeth at the micron level and discovering what several million year old teeth can tell us about the individual whose teeth they were and how rapidly our earliest ancestors matured to adulthood as compared with other great apes.

Evidence of early humans living on the coast in South Africa, harvesting food from the sea, employing complex bladelet tools and using red pigments in symbolic behavior 164,000 years ago, far earlier than previously documented, is being reported in the Oct. 18, 2007 issue of the journal Nature.