March was a fertile month for news concerning human origins and evolution. The good news is that the palaeoanthropologists are at each other’s throats again! I think it is good news because many of them have an air of smugness and triumph, and they get far more money than other Earth scientists (with the exception of those bent on finding a banth on Mars). Tangling with hominins in Kenya is a sure route to trouble, as the finders of “Millenium Man” (Ororrin tugenensis) – Martin Pickford and Brigitte Senut now discover (Butler, D. 2001. The battle of Tugen Hills. Nature, v. 410, p. 508-509). Not only is their claim that the 6 Ma old fossil is the oldest on the route to humanity hotly disputed (Aiello, L.C. and Collard, M. 2001. Our newest oldest ancestor? Nature, v. 410, p. 526-527), but has ended with their taking suit against Richard Leakey and the Kenyan National Museums for unlawful arrest, false imprisonment and malicious harassment over claims that they poached the site where Orrorin was found. Never an easy atmosphere in which to work, human evolution is now one posing considerable dangers, so much so that some specialists will comment only anonymously.
Books in the field always sell like hot cakes, as much for the intrigue and the chutzpa as for the science that they convey. Reviewers become drawn into the hype, despite their best intentions (White, T.D. 2001. Adventures in the Bone Trade: the Race to Discover Human Ancestors in Ethiopia’s Afar Depression, by Jon Kalb. Nature, v. 410, p. 517-518). Areas in Afar and Danakil are physically dangerous because of current hostilities between Eritrea and Ethiopia, and dissatisfaction among the local people. But they have enormous potential for hominin discoveries following those of “Lucy” and Ardepithecus. On a recent visit to Eritrea I heard rumours of what might amount to claim jumping and attempts to acquire material clandestinely from new and potentially productive sites, hopefully without foundation.
Confusion is washing over hominin cladistics as ever more variants of accepted species, and fossils that seem to warrant new species and genera turn up. This is particularly rife for early remains that predate the first stone tools (Lieberman, D.E. 2001. Another face in our family tree. Nature, v. 410, p. 419-20; Balter, M. 2001. Fossil tangles the roots of human family tree. Science, v. 291, p. 2289-2290; ). Of course, much of the confusion stems from every new find seeming to bear different cranial and dental hallmarks, combined with dogged attempts to chart the path of our descent through the remains and a tendency to change genus and species names (Homo habilis is now sometimes assigned to Australopithecus, despite a probable association with primitive stone tools). The latest bush figured by Lieberman is notable for every supposed cladistic link being marked by a query. One gets the impression of rather too much shuffling around of anatomy, and too little consideration of the unseeable, but inevitably vital distinction between the human line and other fossils. There are still very few hominin fossils!
Tools demand consciousness, and probably social links far stronger than those of other apes. Only stone tools survive, from around 2.5 Ma ago, but must represent an advanced culture that arose from earlier beginnings. Abstracting usefulness from surrounding nature and social organisation confer such advantages to its inventors that they set them apart from other animals in relation to natural selection. Fitness no longer applies to the individual organism, but increasingly to its culture shared with others. The formerly unfit becomes fit, and that can play havoc with physiological diversity and thereby the cladists’ shuffling.
Culture confers something equally powerful by enabling its carriers to diffuse beyond their geographic range. The 2 March 2001 issue of Science devotes 33 pages to human migrations (Culotta, E, Sugden, A and Hanson, B. (eds) 2001. Humans on the move. Science, v. 291, p. 1721-1753). For me, this is the most powerful and informative contribution to our self-knowledge in many years. Eight articles cover the earliest Europeans, the relations between modern humans and Neanderthals, the first colonisers of the Americas, the roles of genetics in teasing out our origins and how tools track physiological change. Appearing in the midst of tedious and self-regarding squabbles among the “bone people”, it surely marks a proper line of march in this abidingly gripping branch of Earth science.