In a new research collaboration between the University of Witwatersrand and the University of Adelaide, previously held views on the evolutionary development of the human brain are being challenged. The findings of their studies, published today in
the Royal Society Open Science*, unseats previous theories that
the progression of human intelligence is simply related to the increase in size of the brain.

Their research found that while brain size has increased by about
350% over human evolution, blood flow to the brain increased
by an amazing 600%.
The increase in the supply of blood to the brain appears to be closely linked to the evolution of human intelligence where the human brain has evolved to become not only larger, but more energetically costly
and blood thirsty than previously believed.

Wits Brain Function Research Group co-­author Dr Edward Snelling
says: "Ancient fossil skulls from Africa reveal holes where the arteries
supplying the brain passed through. The size of these holes show how blood flow increased from 3 million year old Australopithecus
to modern humans."

These are Hominin skull casts used to measure the supply
of blood to the brain. Credit: Photo credit: Roger Seymour