Lucy's Cousin

Nature news reports the finding of a new australopithecine in Ethiopia only 35km from the site where Lucy, Australopithecus afarensis, was discovered in 1974. Lucy marked one of the oldest examples of early hominins at that time, living as she did approximately 3.2 million years ago. She has a relatively small cranium, which means a small brain, but was clearly bipedal; thereby resolving the chicken and egg question in relation to large brain capacity and bipedalism. Her skeleton is 40% complete, which is remarkably intact for a specimen that old, and we have learnt an awful lot from her.

This new specimen is contemporaneous with A. afarensis, being 3.3-3.5 million years old, which throws up the scenario that there were possibly several early hominins all wondering around east Africa at the same period. But this shouldn't come as a surprise, it is only in very recent history that we became the only biped on the block when we finished off the last of the neanderthals; before then there had been as many as half a dozen species cohabiting in Africa and through into Asia. Part of the reason that this could happen is demonstrated in the new skeleton. It has a much sturdier and stronger jaw than Lucy does, this would imply that they had a different diet and therefore weren't competing for the same resources.

This new species has been dubbed Australopithecus deyiremeda which roughly translates as 'close relative' in the local Afar language. We shouldn't assume that she (I'm calling her a she) is our ancestor, however, many early hominins died out and weren't a part of the lineage that went on to become the Homo genus. That said, she does make for a wonderful transition fossil, which turns out to have been something of a theme on the blog this week. I shall try to transition into a new area next week.

Model of what Lucy, and possibly A. deyiremeda, may have looked like

Extinction by Fussiness

If there's one thing that really bugs me it's fussy eaters but a new paper from researchers at Oxford University may have found an example where the ramifications of a restrictive diet were more than just annoying me. Australopithecus bahrelghazali was a form of early hominid that forged west out of the rift valley some 4 million years ago; they settled in what is modern day Chad a long way from any other australopithecine yet found. The land was fertile and there were few predators and this allowed them to evolve into a niche that, when push came to shove a million years later, left them facing extinction in the face.

Although there were plenty of different things available to eat research has shown that the thin enamel of their teeth would have restricted their diet to soft, easily chewable plants like sedges. These are not a very nutritious food, which was fine when times were good, but as the climate changed and as predators moved into the territory they simply couldn't eat enough high quality food to survive the new difficult conditions and that, Science Fans, was the end of Australopithecus bahrelghazali.