http://www.tesco-shopping.com/terranovadrho.htm

"Early hominids began eating high-quality foods by scavenging meat and fish around two million years ago. This could
have allowed increased and sustained cerebral cortical growth without increasing body mass. However, early hominids
scav-enged fish opportunistically. For example, a statistical analysis of bone scatter suggests that large numbers of fish
were stranded in pools of water, where they could be caught easily by H habilis, A boisei and H erectus as well as
carnivores. Nevertheless, opportunistic con-sumption increased intelligence, which allowed our ancestors to fish more
often and more successfully. This, in turn, increased omega-3 consumption, which further boost-ed intelligence and led to
early man favouring PUFA-rich fish. Even today, traditional fishers value fat rich fish, such as catfish.

Then, between 100,000 and 200,000 years ago, H sapiens evolv-ed in East African areas rich in trop-ical freshwater fish
and shellfish. It seems that the new human species migrated out of Africa into the rest of the world, rather than evolve
independently. Some older species - H erectus and H neanderthalenis - left Africa, which required the intelligence to adapt
to diverse environments. However, H sapiens was better prepared for new and possibly hostile environments than his
predecessors. For example, H neanderthalenis - which first evolved some 300 thousand years ago - never developed the
same range of tools as H sapiens, which included harpoon-type spears, fish hooks and stone tools. While consumption of
the PUFA-rich diet in the Rift Valley seems a prerequisite for this migration, genetic environmental and climatic changes
also played a role."

Of course, tubers leave no bones. :)

William