Re: Hominid Diet Examined

Marc Verhaegen wrote:
>
> Thank you very much, Travsky. This again beautifully confirms our views on
> apith diets.

You mean OTHERS' views. You do no real work of your own.

> From a paper with prof.Puech (one of the very first to investigate afarensis
> enamel electromicroscopically, see refs below):
>
> "Hominid Lifestyle and Diet Reconsidered: Paleo-Environmental and
> Comparative Data"
> Marc Verhaegen & Pierre-François Puech 2000
> Musée de l'Homme à Paris, BP 191, 30012 Nîmes 4, France
> Human Evolution 15: 151-162
> (the whole paper can be found at
> http://allserv.rug.ac.be/~mvaneech/Verhaegen.html )
> ... Dental studies suggest that whereas gracile australopithecines preferred
> softer fruits and vegetables, the robusts' diet included harder food items
> (e.g. Robinson, 1954; Du Brul, 1977; Walker, 1981; Puech, 1992; Lee-Thorp et
> al., 1994). Estimates of robust australopithecine bite force suggest
> 'low-energy food that had to be processed in great quantities' and food
> objects 'hard and round in shape' (Demes & Creel, 1988). Du Brul (1977)
> noticed dental isms between the robust australopithecines and the
> bamboo-eating giant panda Ailuropoda melanoleuca (broad, high and heavy
> cheekbones, reduced prognathism and front teeth, broad back teeth, premolar
> molarisation), as opposed to gracile australopithecines, respectively
> non-panda bears.
> Papyrus and reed were present in the paleo-environment of the later
> australopithecines (e.g. Olduvai, Chesowanja, Kromdraai), and Cyperaceae and
> Gramineae are part of the diet of living African hominoids. Gorillas eat
> sedges and bamboo shoots and stalks, gorillas and chimpanzees eat cane,
> chimps and humans eat water lilies, and rice and other cereals are staple
> food for humans. Supplementing their diet with parts of grasslike plants
> might have been enabled the robusts to bridge the dry season, when fruits
> and soft vegetables were scarce.
> Studies of dental enamel microwear provide other details. In the early
> australopithecines of Garusi-Laetoli and Hadar (A. afarensis 4-3 Myr BP),
> the cheekteeth enamel has a polished surface and the microwear looks like
> that of the capybara Hydrochoerus hydrochaeris and that of the mountain
> beaver Aplodontia rufa (Puech et al., 1986). These animals are semi-aquatic
> rodents that feed mainly on sappy marsh and riverside herbs, grasses and
> bark of young trees. It has recently become clear that Western lowland
> gorillas G. g. gorilla spend some time eating aquatic herbaceous vegetation
> (AHV) like Hydrocharitaceae herbs and Cyperaceae sedges (Doran & McNeilage,
> 1997).
> Comparisons of molar enamel in South African fossils show that A. robustus
> ate substantially more hard food items than A. africanus (Grine & Kay,
> 1988). Incisal microwear suggests that A. robustus may have ingested foods
> that required less extensive incisal preparation than the foods consumed by
> A. africanus, such as fruits (Ungar & Grine, 1991), and 'incisors need not
> be employed in the manipulation of hard objects' (Ungar & Grine, 1989).
> The enamel of the East African robusts (Olduvai and Peninj) displays more
> pits, wide parallel striations and deep recessed dentine, resembling that of
> the beaver Castor fiber, that eats riverine and riverside herbs, roots of
> water lilies, bark and woody plants in a temperate climate. 'Many food
> plants growing in marsh land and indeed many grasses, have high
> concentrations of siliceous particles known as opal phytoliths. The
> consumption of such foods produces a great deal of wear, and the enamel and
> dentine have a blunted appearance. Ancient Egyptians ate papyrus shoots
> (Puech et al., 1983b) and we suppose that [O.H.16] did the same with swamp
> margin plants' (Puech, 1992). Whereas the East African robusts seem to have
> had aquatic plants and papyrus shoots in their diet and ate more woody
> plants than the earlier australopithecines, habilis O.H.16 apparently
> supplemented the AHV of the earlier australopithecines with acid fruits
> (Puech, 1984). In the habilis cheekteeth, the margins of the striae have
> been polished and slightly etched, resembling the microwear of the coypu
> Myocastor coypus. This rodent feeds on reed, sedges, marsh plants, fruits
> and molluscs in river and lake margins. It thus seems that an early
> australopithecine diet of fruits (larger front teeth) and AHV (polishing)
> was supplemented with unripe fruits (acid etching) in habilis, and with
> woody plants in the robusts (more wear).
> The suggestion of Walker (1981) that A. boisei KNM-ER 406 and 729 were
> bulk-eaters of whole fruits, 'small, hard fruits with casings, pulp, seeds
> and all', could explain the deep recessed occlusal dentine, but not the
> glossy appearance of heavily polished enamel, which is more typical for
> marsh plant feeders. In terrestrial grazers such as sheep, tooth wear is
> faster, with a different gradient and fabric-like grooves.
> These microwear data are consistent with the strontium/calcium ratios in
> Swartkrans fossils (Sillen, 1992). Apart from partial carnivory (rather
> unlikely with the robusts' dentition, see Du Brul, 1977; Walker, 1981),
> Sillen provides two possible explanations for the low Sr/Ca of A. robustus:
> eating leaves and shoots of forbs and woody plants (kudu diet), and eating
> food derived from a wet microhabitat, for instance, from well-drained
> streamside soils.
> In our opinion, the coincidence of several independent lines of evidence
> (paleo-milieu, dental morphology, enamel microwear, Sr/Ca ratios) leaves
> little doubt that some or all australopithecines fed regularly on AHV
> growing in shallow waters, much more than Western gorillas do today
> (Chadwik, 1995; Doran & McNeilage, 1997). It is conceivable that hominid
> bipedality first arose in the shallow waters of gallery or mangrove or swamp
> forests. 'One of the strong points about the aquatic theory is in explaining
> the origin of bipedality. If our ancestors did go into the water, that would
> forced them to walk upright' (Stringer, 1997). That a gradual evolutionary
> transition from forest to marshland is possible is illustrated by the
> Western lowland gorillas that spend some time feeding on AHV, wading
> bipedally, sitting and playing in marshy forest clearings (Chadwik, 1995;
> Doran & McNeilage, 1997; NDR TV film, 1997).
>
> :-)
>
> Marc Verhaegen
>
> http://www.onelist.com/community/AAT
>
> _______
>
> "Rich Travsky" <traRvEsky@xxxxxxxxxxxxxxx> wrote in message
> news:42F39C78.2AFB1864@xxxxxxxxxxxxxxxxxx
> > Sez it's supposed to be in the Aug 4th Nature, but nothing on line yet...
> >
> >
> > http://live.psu.edu/story/12922
> >
> > University Park, Pa. -- A Penn State researcher is part of the team that
> > developed techniques that have generated insights into dietary
> divergences
> > between some of our human ancestors, allowing scientists to better
> > understand the evolutionary path that led to the modern-day diets that
> > humans consume.
> >
> > "Our new techniques are allowing us to get beyond simple dichotomies and
> > helping us understand the processes by which dietary evolution is
> > working," said Peter Ungar, professor of anthropology at the University
> > of Arkansas.
> >
> > Ungar and Robert Scott, postdoctoral fellow at the University of
> Arkansas,
> > with colleagues at the Worcester Polytechnic Institute, State University
> > of New York at Stony Brook, Johns Hopkins University School of Medicine
> > and Penn State, report their findings in the August 4 issue of the
> journal
> > Nature.
> >
> > The researchers, including Alan Walker, Evan Pugh professor of biological
> > anthropology and biology at Penn State, investigated microscopic wear on
> > the teeth of two species of ancient hominims -- Australopithecus
> africanus,
> > which lived between 3.3 million and 2.3 million years ago, and
> Paranthropus
> > robustus, which lived between 2 million and 1.5 million years ago. The
> pits
> > and scratches found on the teeth offer a visual history of the type of
> food
> > consumed by the tooth's owner. Pits indicate a diet of hard, brittle
> foods,
> > like nuts and seeds, while scratches imply a diet of tough foods, like
> > leaves and possibly meat.
> >
> > Traditional examinations of these ancient teeth -- counting pits and
> lines
> > on a black and white electron micrograph image -- suggested that A.
> > africanus ate tough foods and P. robustus dined on hard, brittle fare.
> > However, the researchers used a new technique developed by Ungar and his
> > colleagues that combines engineering software, scale-sensitive fractal
> > analysis and a scanning confocal microscope to create a reproducible
> texture
> > analysis for teeth -- and the analysis tells a more complete story. The
> > researchers looked at both roughness, or complexity, and directionality
> in
> > the teeth they examined.
> >
> > "Since food objects interact with teeth, we have different kinds of
> > complexity in different diets. Directionality also correlates with diet,"
> > Scott said. Hard foods like nuts and seeds tend to lead to more complex
> tooth
> > profiles, while tough foods like leaves lead to more scratches, which
> > corresponds with directionality.
> > ...
> > The analysis showed that the two species had significant amounts of
> overlap in
> > their diets and that while P. robustus had more complexity in its tooth
> wear,
> > indicating that it ate more hard and brittle foods than A. africanus, it
> ate
> > tough foods as well.
> >
> > The researchers believe that this indicates that the species frequently
> ate the
> > same types of foods, but that in times of scarcity or seasonal changes,
> P.
> > robustus changed its diet to include foods that differed from those of A.
> > africanus.
> >
> > "The difference in their evolution in terms of diet is not driven by
> their
> > preferences, but by scarcity," Ungar said. "It gives you a whole new way
> of
> > thinking about dietary adaptation."
> > ...
> >
> >
> > scarcity...
.

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