Humans bite different from gr.apes/apiths
The robust jaws & formidable teeth of some of our ancestors and ape cousins
may suggest that humans are wimps when it comes to producing a powerful
bite: but a new study has found the opposite is true, with major
implications for our understanding of diet in ancestral humans.
The surprise findings suggest that early modern humans did not necessarily
need to use tools and cooking to process high-nutrient hard foods, such as
nuts - and perhaps less tough foods such as meat - but may have lost an
ability to eat very tough items, such as tubers or leaves.
In the first comparison of its kind, Australian researchers have found that
the lightly built human skull has a far more efficient bite than those of
the chimp, gorilla and orang-utan, and of two prehistoric members of our
family, Australopithecus africanus and Paranthropus boisei.
They found that modern humans can achieve relatively high bite forces using
less-powerful jaw muscles. In short, the human skull does not have to be as
robust because, for any given bite force, the sum of forces acting on the
human skull is much less.
These results also explain the apparent inconsistency of very thick tooth
enamel in modern humans - a feature typically associated with high bite
forces in other species. Thick enamel and large human tooth roots are well
adapted to take high loads when biting.
The study appears in a paper in the journal Proceedings of the Royal Society
B by a team led by Dr Stephen Wroe, of the Computational Biomechanics
Research Group in the UNSW's School of Biological, Earth and Environmental
These result calls into question previous suggestions that the evolution of
a less robust skull in modern humans involved a trade-off for a weaker bite
or was necessarily a response to behavioural changes, such as switching to
softer foods or more processing of foods with tools and cooking. It has also
been suggested that human jaw muscles were reduced to make way for a larger
"However plausible those ideas may seem they have been based on very little
by way of comparative data: for example, there are no actual records of bite
force collected from living members of any other ape species, " says Dr
Wroe. "It turns out that we don't have a wimpish bite at all - it is very
efficient and powerful.
"When we're biting down in vertical plane, at the back of the jaw our bite
is about 40-50% more efficient than it is for all great apes. It's even more
efficient when biting at the front of the jaw.
"We've only looked at two extinct hominins in this study, but, for our size,
we humans are comparable in terms of maximum bite force to these fossil
species, which include 'nutcracker man', renowned for its particularly
massive skull and jaw muscles. Size matters, but efficiency matters more -
and humans are very efficient biters ...
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