Early Humans eat bark – So what are the evolutionary implications?

Australopithecus sediba
(image Lee Berger)

One of the problems I have is as I no longer have open access to a university library and because of pay walls I have to depend on secondary reports in magazines like the New Scientist. 

The recent work on dental plaque of Australopithecus sediba published in Nature shows that, among other things, they ate bark, and had a diet different to most other hominins. The News Scientist article implies that this is a mystery – but surely in the light of other research on evolutionary pathways variations in diet between different hominins should not be a surprise. Everything points to different groups splitting apart and evolving independently for a time, almost certainly because they were living in different habitats and exploiting food sources in different ways. However they were still able to breed when they came together and it is likely that many of the genetic differences between us and apes may have come about in this way – with gene tic differences between us and our ape forebears having independently evolved in different sup-species.

If this is the case the more different environments our ancestors exploited, and the more different food sources they used, the greater the variety of gene-change options available for our own development. For instance in the past there had been theories that our early ancestors might have spent some time living in an aquatic environment. This seems unlikely if we restrict our thinking to a single descent path – but the new branching and recombining model of our ancestral tree may well end up include input from some yet to be identified sub-species which specialised in fishing!