Research 'final nail in the coffin' of Paranthropus as hard object
feeders

Date:
July 23, 2021
Source:
University of Otago
Summary:
New research debunks a long-held belief about our ancestors'
eating habits.



FULL STORY ==========================================================================
New research from the University of Otago debunks a long-held belief
about our ancestors' eating habits.


==========================================================================
For more than 60 years, researchers have believed Paranthropus, a close
fossil relative of ours which lived about one to three million years
ago, evolved massive back teeth to consume hard food items such as seeds
and nuts, while our own direct ancestors, the genus Homo, is thought to
have evolved smaller teeth due to eating softer food such as cooked food
and meats.

However, after travelling to several large institutes and museums in
South Africa, Japan and the United Kingdom and studying tooth fractures
in more than 20,000 teeth of fossil and living primate species, Dr Ian
Towle, an Otago biological anthropologist, working with Dr Carolina Loch,
of the Faculty of Dentistry, says this "neat picture is far more complex
than once thought." "By individually studying each tooth and recording
the position and size of any tooth fractures, we show tooth chipping
does not support regular hard food eating in Paranthropus robustus,
therefore potentially putting an end to the argument that this group as
a whole were hard food eaters," he says.

Dr Towle says the findings challenge our understanding of dietary and behavioural changes during human evolution.

"The results are surprising, with human fossils so far studied -- those
in our own genus Homo -- showing extremely high rates of tooth fractures, similar to living hard object eating primates, yet Paranthropus show
extremely low levels of fracture, similar to primates that eat soft
fruits or leaves.

"Although in recent years there has been a slow acceptance that another
species of Paranthropus, Paranthropus boisei, found in East Africa,
was unlikely to have regularly eaten hard foods, the notion that
Paranthropus evolved their large dental apparatus to eat hard foods has persisted. Therefore, this research can be seen as the final nail in the
coffin of Paranthropus as hard object feeders." The fact that humans
show such contrasting chipping patterns is equally significant and will
have "knock on" effects for further research, particularly research on
dietary changes during human evolution, and why the human dentition has
evolved the way it has, he says.

"The regular tooth fractures in fossil humans may be caused by non-food
items, such as grit or stone tools. However, regardless of the cause,
these groups were subjected to substantial tooth wear and fractures. So,
it raises questions to why our teeth reduced in size, especially compared
to groups like Paranthropus." Dr Towle's research will now focus on if
our dentition evolved smaller due to other factors to allow other parts
of the skull to expand, leading to evolution then favouring other tooth properties to protect it against wear and fracture, instead of increased
tooth size.

"This is something we are investigating now, to see if tooth enamel
may have evolved different characteristics among the great apes. Our
research as a whole may also have implications for our understanding
of oral health, since fossil human samples typically show immaculate
dental health.

"Since extreme tooth wear and fractures were the norm, our
ancestors likely evolved dental characteristics to not just
cope with but actually utilise this dental tissue loss. For
example, without substantial tooth wear our dentitions can
face all sorts of issues, including impacted wisdom teeth,
tooth crowding and even increased susceptibility to cavities." ========================================================================== Story Source: Materials provided by University_of_Otago. Note: Content
may be edited for style and length.


========================================================================== Journal References:
1. Ian Towle, Joel D. Irish, Carolina Loch. Paranthropus robustus tooth
chipping patterns do not support regular hard food
mastication. Journal of Human Evolution, 2021; 158: 103044 DOI:
10.1016/j.jhevol.2021.103044
2. Ian Towle, Carolina Loch. Tooth chipping prevalence and patterns in
extant primates. American Journal of Physical Anthropology, 2021;
175 (1): 292 DOI: 10.1002/ajpa.24232
3. Ian Towle, Carolina Loch, Joel D. Irish, Alessio Veneziano,
Tsuyoshi Ito.

Chipping and wear patterns in extant primate and fossil hominin
molars: `Functional' cusps are associated with extensive wear but
low levels of fracture. Journal of Human Evolution, 2021; 151:
102923 DOI: 10.1016/ j.jhevol.2020.102923 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210723105253.htm

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