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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Itadakimasu!

That's Japanese for "Let's eat!" Taragana is reporting on research done on early hominids to determine what they ate. The answer:

Our early ancestors, living in what is now northern Kenya, feasted on fish and other aquatic animals such as turtles and crocodiles - foods which probably played a major role in the development of a larger, more human-like brain, new research reveals.

The study, which offers the first-ever evidence of dietary variety among early pre-humans, appears in Proceedings of the National Academy of Sciences. A team of researchers that included Johns Hopkins University geologist has found that early hominids living in what is now northern Kenya ate a wider variety of foods than previously thought, including fish and aquatic animals such as turtles and crocodiles. Rich in protein and nutrients, these foods may have played a key role in the development of a larger, more human-like brain in our early forebears, which some anthropologists believe happened around 2 million years ago, according to the researchers’ study.

It takes quite a bit of intelligence to incorporate all of those different kinds of foods into a single diet. It is always interesting to see a report like this that basically ends "they were smarter than we thought."

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As Climate Changes, So Do Animals' Diets

A story in e! Science News reports that researchers from The University of Florida have conducted a study of mammalian teeth and discovered that, as climate changes, the diets of many mammals shift to accommodate the changes:

Led by Florida Museum of Natural History vertebrate paleontologist Larisa DeSantis, researchers examined fossil teeth from mammals at two sites representing different climates in Florida:

a glacial period about 1.9 million years ago and a warmer, interglacial period about 1.3 million years ago. The researchers found that interglacial warming resulted in dramatic changes to the diets of animal groups at both sites. The study appears in the June 3 issue of PLoS ONE.

"When people are modeling future mammal distributions, they're assuming that the niches of mammals today are going to be the same in the future," DeSantis said. "That's a huge assumption."

Co-author Robert Feranec, curator of vertebrate paleontology at the New York State Museum, said scientists cannot predict what species will do based on their current ecology.

"The study definitively shows that climate change has an effect on ecosystems and mammals, and that the responses are much more complex than we might think," Feranec said.

We know that when the African climate shifted toward the end of the Miocene, the monkeys adapted to the savannas while the higher apes adapted to the jungles. Rather than do either, one group likely exploited the forest/fringe environment, which allowed them to be more generalists. It is probably this group that gave rise to the earliest hominids.