Scientists Criticize Habitat Claims For "Ardi"

In a number of posts since NOT A CHIMP was published I have detailed the findings and claims of the paleo group headed by Tim White with respect to their discovery and investigation of "Ardi" - Ardipithecus ramidus - dating back some 4.4 million years. We now had another likely human ancestor who existed shortly after the split of chimpanzees and humans from the common ancestor. Anatomically, Ardi was not very chimp-like, having an upright gait. But her feet suggested she was, nevertheless, adapted for a heavily forested habitat in which "branch-walking" in trees was as much a part of her repertoire as walking in the surrounding grassland. All this suggested to White that Ardi makes a much better model for the common ancestor than today's chimps. It also meant, to White, that this substantial evolution of muscles and skeleton was not precipitated, as conventional wisdom has it, by the rapid replacement of dense sub-tropical forest by drier savanna vegetation.

Now a group of scientists led by Thure Cerling, from the University of Utah, question White's conclusions, saying they "explained away" the presence of prairie-adapted rodents in the surrounding substrate to Ardi's fossilised skeleton, and that there are the remains of several tropical grassland species in soil taken from the site. They suggest Ardi's habitat consisted of 25% or less forest and approx. 75% grassland, rather than the 60% tree cover that can normally be termed forest. Neither do they like White's interpretation of the tooth enamel of herbivores removed from the same stratum, saying that they betray browsing in more open grassland than White maintains. So, according to Cerling, the "savanna" hypothesis - that the arrival of open grassland prompted early hominids down from the trees and into a more efficient bipedal gait - still stands as a reasonable version of events. White, of course, disagrees, and it will be interesting to see how this argument plays out.

Travis's Owner Dies

At the top of the NOTACHIMP blog I recount the tragic case of Travis the chimp, killed by police after he went on the rampage and horribly disfigured his helper. This very unhappy tale has now concluded with another tragic event, the premature death of Travis's owner, Sandra Herold. Herold had endured the death of her only child in 2000, the death of her husband in 2004, and the death of her pet chimp and company mascot, Travis, in 2009. She suffered a fatal aortic aneurysm.