Why chimps are not us ...

They say that when a new girl enters your life everything changes - and that is certainly true for students of human evolution. The discovery of Ardipithecus ramidus - affectionately known as “Ardie” - has shattered the long-held consensus that the common ancestor of humans and chimps must have resembled a chimpanzee and that our human ancestors must have passed through a knuckle-walking phase before becoming bipedal and bounding off into the newly-formed savannas to begin the long march that led to us - leaving chimpanzees in their sub-Saharan tropical forests indolently frittering away six million valuable years in some kind of evolutionary stasis.

Ardi’s age means either that evolution must have really pressed the pedal to the metal for one and a half million years to get to her from a chimp-like common ancestor, or, much more likely, that our common ancestor was a bipedal primate from which both humans and chimpanzees evolved, over the same length of time, but along markedly different trajectories. Thanks to intermediate fossils like the Australopithecenes and Homos erectus we have some sketchy idea of the evolutionary ground we hominins have covered, but Ardi suggests that chimps have also undergone significant evolution into the very specialised, mainly arboreal primates we see today.
Certainly, Ardi is very unlike a chimp. We know she walked upright by the position of the foramen magnum - the aperture in the skull that admits the spinal cord. Her dental ironmongery lacks the huge canines typical of chimpanzees. Her hands lacked the rigid wrists a knuckle-walker must have if the arms are to support body weight. Her feet are an interesting mix of advanced and primitive features, having a large prehensile big toe but otherwise a plate-like structure suitable for launching forward with a shambling gait.

All this palaeo-anthropological detail, and the hasty re-jigging of family trees it necessitates, has an importance far beyond the arcane field of human origins research. It has dealt a death blow to the “chimps ‘r us” industry by which the popular science media, aided and abetted by a number of scientists who should know better, have used the chimpanzee as a template for modern human behaviour. To the extent that we are violent rapists, pillagers and warmongers, it is said, we owe it to the chimpanzee, while our opposite propensities for reconciliation, conflict resolution, love and social harmony are often explained by comparing us with the pygmy chimpanzee or bonobo. All that can be torn up because, as Tim White, lead scientist on the Ardi find, exclaims: “Chimpanzees can no longer be used as proxies for human behaviour”.

Worse still, evidence of the very narrow genetic distance between humans and chimps, and their modest abilities in tool manufacture, mathematics, language, empathy and altruism, have been repeatedly used to bolster claims that we should share the same genus - Homo - with them and accord them human rights. Knowledge that chimps do not resemble our common ancestor and have been independently evolving away from us for six million years will help put paid to that and force us to distance ourselves from chimpanzees and value them for what they are rather than what we see, narcissistically, of us, reflected in them.

Jeremy Taylor is author of Not A Chimp