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Humans evolved smarter as their brain became more blood-thirsty?

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Posted September 2, 2016

There is a general belief that humans evolved to be smarter and smarter because their brain got bigger and bigger. However, some scientists have doubted that for a while, because bigger brain does not necessarily mean higher intelligence. Now a new study from an international team of scientists, led by the University of Adelaide, found that the process of humans evolving to be smarter is related to a better supply of blood to the brain.

There is no denying that brain of human ancestors was significantly smaller, but they were also much less energetically costly. Image credit: Tim Evanson via Flickr, CC BY-SA 2.0

There is no denying that brain of human ancestors was significantly smaller, but they were also much less energetically costly. Image credit: Tim Evanson via Flickr, CC BY-SA 2.0

There is no denying that human brain got bigger as evolution progressed. However, at the same time brain started requiring more and more blood – it became more energetically costly. As this new study shower, bigger brain was much more blood thirsty than previously believed. Of course, researching inflow of blood to the brain of human ancestors is not an easy task as they are gone for thousands of years. However, scientists relied on their sculls that have been discovered around the Earth. These sculls have two holes at the base for the arteries to pass to the brain. Therefore, scientists could see how these holes changed over the course of evolution.

One would think that bigger brain obviously need more blood, but the big surprise of the study was that there is a significant difference between the growth of the brain and increase in blood flow. Professor Emeritus Roger Seymour, leader of the project, said: “Brain size has increased about 350% over human evolution, but we found that blood flow to the brain increased an amazing 600%. 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”. Brain simply needed more nutrients to deal with new functions.

This is very interesting study, because before it scientists believed that brain activity of our ancestors is impossible to research. Now they discovered that holes for arteries to pass to the brain are actually accurate gauges to measure the inflow of blood. Scientists also note that increasing blood inflow matches other points in timeline of humans – longer childhood, more complex cooperation in hunting and other activities, defending territory and others.

Now that scientists have basic methodology nailed down, it will be interesting what else they will discover. For now it looks proven that smarter brains are firstly blood-thirsty brains and not just bigger ones.

Source: adelaide.edu.au

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