Tech UPTechnologyThey discover why humans have such a big brain

They discover why humans have such a big brain

Over millions of years, since human and chimpanzee ancestors parted ways, our brains have practically tripled in size, while theirs has barely changed. How did Homo sapiens achieve that extraordinary brain volume? A team of researchers has developed a model that shows that our gray matter constantly evolved over time (more than 3 million years), from which it follows that it is unlikely that our intelligence has been selected for a particular behavior .

The first hominins had a similar brain size to chimpanzees, and they have increased dramatically since then. Therefore, it is important to understand how we got here,” says Andrew Du, paleobiologist at the University of Chicago and co-author of the work.

Several hypotheses are based on dietary changes, better blood flow, or metabolic changes to drive additional neurons.

“Conventional wisdom is that our large brains had evolved in a series of staggered increments that each made our ancestors smarter,” says Bernard Wood of George Washington University, lead author of the study. “ It is not surprising that reality is more complex , without a clear link between brain size and behavior.”

The new study, which has examined nearly 100 fossils (94 specifically) of 13 different human species dating back to when Australopithecus afarensis , whose most famous member “Lucy” was unearthed in Ethiopia, roamed the Earth, finding that the size of the brain it tripled over the past three million years, in a process that was probably slow and consistent, as opposed to a series of ‘staggered increases’.

Experts say the change from our ancestral family tree was driven by increasing complexity as humans developed culture, language, and the ability to make tools. A long and hard training.

The researchers compare it to rubgy training: “The same goes for brains: we found that existing species developed larger brains, larger-brain species appeared, and smaller-brain species became extinct,” says Du.

Far from being studied as a line of descent from the 3.2 million-year-old Australopithecus to our close cousin Homo erectus, who lived half a million years ago, the specimens were divided into their family lineages. This allowed the researchers to compare the changes in each branch, as well as across different branches.

What they saw was that evolution within each group gradually boosted brain size.

As hominin species evolved (larger brains), more limited brain populations were slowly being replaced by larger brains.

Meanwhile, the brain volumes within each species continually expanded with subsequent generations.

The study falls short of speculating on what forces drove the gradual change in brain volume, but it helps limit the hypotheses to those that support slow and steady rise rather than sudden, rapid steps.

The size of the brain is also not the beginning and the end of cognitive functioning. While having more neurons may offer more opportunities to develop additional skills, the connections between them are vital in determining the functionality of the brain.

Reference: Pattern and process in hominin brain size evolution are scale-dependent. Andrew Du, Andrew M. Zipkin, Kevin G. Hatala, Elizabeth Renner, Jennifer L. Baker, Serena Bianchi, Kallista H. Bernal, Bernard A. Wood Proceedings of the Royal Society B 2018 DOI: DOI: 10.1098 / rspb.2017.2738

Image credit: Andrew Du.

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