by Staff Writers
Adelaide, Australia (SPX) Sep 01, 2016
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, published in the Royal Society journal Open Science, allowed the researchers to track the increase in human intelligence across evolutionary time.
"Brain size has increased about 350% over human evolution, but we found that blood flow to the brain increased an amazing 600%," says project leader Professor Emeritus Roger Seymour, from the University of Adelaide. "We believe this 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.
"To allow our brain to be so intelligent, it must be constantly fed oxygen and nutrients from the blood.
"The more metabolically active the brain is, the more blood it requires, so the supply arteries are larger. The holes in fossil skulls are accurate gauges of arterial size."
The study was a new collaboration between the Cardiovascular Physiology team in the School of Biological Sciences at the University of Adelaide and the Brain Function Research Group and Evolutionary Studies Institute at the University of the Witwatersrand.
Co-author Dr Edward Snelling, University of the Witwatersrand, 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 three million-year-old Australopithecus to modern humans. The intensity of brain activity was, before now, believed to have been taken to the grave with our ancestors."
Honours student and co-author Vanya Bosiocic had the opportunity to travel to South Africa and work with world renowned anthropologists on the oldest hominin skull collection, including the newly-discovered Homo naledi.
"Throughout evolution, the advance in our brain function appears to be related to the longer time it takes for us to grow out of childhood. It is also connected to family cooperation in hunting, defending territory and looking after our young," Ms Bosiocic says.
"The emergence of these traits seems to nicely follow the increase in the brain's need for blood and energy."
University of Adelaide
All About Human Beings and How We Got To Be Here
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|