A University of Adelaide-led project has overturned the theory that the evolution of human intelligence was simply related to the size of the brain—but rather linked more closely to the supply of blood to the brain. The international collaboration between Australia and South Africa showed that the human brain evolved to become not only larger, but more energetically costly and blood thirsty than previously believed. The research team calculated how blood flowing to the brain of human ancestors changed over time, using the size of two holes at the base of the skull that allow arteries to pass to the brain. The findings allowed the researchers to track the increase in human intelligence across evolutionary time. Authors note that brain size has increased about 350% over human evolution, but the blood flow to the brain increased an amazing 600%, which is possibly related to the brain's need to satisfy increasingly energetic connections between nerve cells that allowed the evolution of complex thinking and learning. http://phys.org/news/2016-08-smarter-brains-blood-thirsty.html Paper: http://rsos.royalsocietypublishing.org/content/3/8/160305
