Did Australopithecines Have Bonding Patterns Like Modern Chimpanzees?

The Guardian has a story on research done with Australopithecus africanus and A. robustus teeth that suggests that, while the men did not wander far from their birth site, the women did. Ian Sample writes:

“Here we have the first direct glimpse of the geographic movements of early hominids, and it appears the females preferentially moved away from their residential groups,” said lead author, Sandi Copeland at the Max Planck Institute for Evolutionary Anthropology in Leipzig.

A similar situation is seen among modern chimpanzees, where females tend to move out of their groups, in part because males form strong ties that help them protect a troop's territory.

“By virtue of the fact that the males choose to remain, the females are indirectly forced to leave their communities in order to avoid close inbreeding. It could be that among these early hominins, female dispersal has some correlation to close cooperative behaviour between males,” Copeland added.

Another piece of the puzzle.

A. boisei Ate Soft Foods

Now it looks like there is evidence that the hyper-robust Australopithecus boisei did not survive on a diet of nuts and berries, as has been thought for decades. New research by Thure Cerling suggests that their primary subsistence was on grass, instead. On the other hand, the LiveScience article by Jeanna Bryner notes:

An early human with a big mouth made for chomping strangely preferred to eat soft, squishy fruits, new dental analyses suggest.

The finding — the big guy's teeth showed only light wear — might force scientists to downgrade everything they thought they knew about hominids' diets. For starters, the findings could cause this hominid, Paranthropus boisei [or Australopithecus boisei], to relinquish rights to its long-held moniker, the Nutcracker Man, in the eyes of anthropologists.

The Nutcracker Man lived from about 2.3 million years ago to 1.2 million years ago, before vanishing from the fossil record. He boasted a huge jaw with massive chewing muscles and flat, tough teeth whose crushing power could obliterate the roots and nuts of his home on the African savanna.

This is in stark contrast to the recent article by Cerling et al., which states very clearly:

Carbon isotope studies of P. robustus from South Africa indicated that it consumed some plants using C4 photosynthesis such as tropical grasses or sedges, but were also consistent with most of its dietary carbon (approximately 70%) having been derived from the C3 food items favored by extant chimpanzees (Pan troglodytes) such as tree fruits. In contrast, stable isotopes measurements of two P. boisei specimens from Tanzania suggested a high component of C4 biomass in its diet...¹

In this case, C4 biomass is grasses and sedges. The PLoS article advocating the fruit position by Ungar et al. has this to say:

While the craniodental functional morphology Paranthropus boisei suggests an ability to generate and dissipate forces associated with the consumption of extremely hard or tough foods, microwear texture analysis offers no evidence that these hominins regularly did so.²

They list as a possibility that boisei ate fruit and suggest that it may have practiced a diet like the modern gorilla.

At this point, the only thing the two papers seem to have in common is that A. boisei ate softer foods than A. robustus. It will still have to necessitate a subsistence model change for this hominin.


Articles cited:

¹Cerling, T. E., Mbua, E., Kirera, F. M., Manthi, F. K., Grine, F. E., Leakey, M. G., et al. (2011). Diet of Paranthropus boisei in the early Pleistocene of East Africa. Proceedings of the National Academy of Sciences.
doi: 10.1073/pnas.1104627108

²Ungar, P. S., Grine, F. E., & Teaford, M. F. (2008). Dental Microwear and Diet of the Plio-Pleistocene Hominin Paranthropus boisei. PloS one, 3 (4), e2044.
doi: 10.1371/journal.pone.0002044


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Ah, the Life!

The Tribune Newspaper of Swartkrans has an article about a former factory manager who is now hunting for fossils in South Africa. According to the story by Robyn Dixon:

[Morris] Sutton, 47, an archaeologist, was a Memphis, Tenn., factory manager who grew tired of the flat horizon of commerce and manufacturing and of laying off fellow employees. So he quit to pursue his hobby: hunting for fossils and Stone Age tools. He went back to college to study archaeology and later moved to South Africa, where he is a postdoctoral researcher with the Institute for Human Evolution at the University of the Witwatersrand.

Now that would be fun! Swartkrans is a site that was first excavated by Robert Broom in the 1930s and revealed Australopithecus robustus remains, including some almost complete skulls, such as the one on the left, and a complete vertebral column, showing without a shadow of a doubt that these creatures with small, ape-like skulls were walking upright like modern humans.



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