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Starchy tubers gave our ancestors' brains a boost
a.. 16 September 2007
b.. Bob Holmes
c.. Magazine issue 2621
A DRAMATIC shift in diet sometime during the evolution of modern humans has
left its imprint on our genome. The discovery could provide some of the
strongest evidence to date in support of a controversial hypothesis that
purports to explain why humans, alone among all the apes, suddenly evolved
such big brains.

One plausible reason is that early hominins suddenly stumbled on a new, rich
food source capable of fuelling a large, energetically expensive brain. For
many years, anthropologists presumed the crucial food source was meat, which
became more accessible as our ancestors began to use stone tools for hunting
or cutting. More recently, however, others have proposed an alternative -
starchy tubers. Proponents of this view argue that early hominins had teeth
better suited to grinding plant matter than tearing flesh. Recent studies of
isotope ratios in hominin fossils also suggest a plant-rich diet.