Tiny discovery could explain why our brains beat Neanderthal brains
<p dir="ltr">Our brains are incredibly complex, even in comparison to some of our closest animal relatives - and now we’re one step closer to knowing why.</p>
<p dir="ltr">Human brains are made up of a whopping 86 billion neurons on average, which is up to three times more than primates.</p>
<p dir="ltr">In a breakthrough study, scientists found that one change in our genes helps our brains develop more neurons than other animals, as well as our extinct cousins, the Neanderthals.</p>
<p dir="ltr">Although our brains are roughly the same size as those belonging to Neanderthals, ours are differently shaped and allowed us to create technologies that our cousins never did.</p>
<p dir="ltr">A team of scientists at the Max Planck Institute of Molecular Cell Biology and Genetics went looking for differences between our and Neanderthal brains and focused on the neocortex, a region of the brain behind our foreheads that is the largest and most recently developed part of our brain.</p>
<p dir="ltr">While focusing on a particular gene, called <em>TKTL1</em>, the team found that the chain amino acids that make up the gene in modern humans has just one difference from the same gene in Neanderthals and other mammals.</p>
<p dir="ltr">After looking at previously published data, they found that <em>TKTL1 </em>was mostly expressed in progenitor cells - a type of cell that can become more specialised cells - called basal radial glia, which are responsible for producing neurons during development.</p>
<p dir="ltr">To test their findings, the researchers introduced the gene into two groups of mice, which don’t express either version of the gene. One group received the modern version of the gene which humans have, while the other received the archaic version.</p>
<p dir="ltr">The mice with the modern form of the gene went on to produce more basal radial glia, which then resulted in more cortical neurons developing, in comparison to those with the older version of the gene.</p>
<p dir="ltr">Repeating the experiment in ferrets, which also carry the older version of the gene and have folds in their brains, they found that animals with the modern gene produced more neurons and had larger brain folds.</p>
<p dir="ltr">Finally, they went to verify their findings in human foetal neocortex cells - this time by removing the <em>TKTL1 </em>gene. Cells without the modern gene produced fewer of the progenitor cells.</p>
<p dir="ltr">Although they stress that additional genes may be behind why we have more neurons than our relatives, Wieland Huttner, one of the researchers involved, said the study “makes the point that this one gene is an essential player” for shaping our big brains.</p>
<p dir="ltr">Christoph Zollikofer, a paleoanthropologist at the University of Zurich who wasn’t involved in the study, said the study presents a “smoking gun” showing how our brains are different from those of Neanderthals.</p>
<p dir="ltr">The study was published in the journal <em><a href="https://www.science.org/doi/10.1126/science.abl6422" target="_blank" rel="noopener">Science</a></em>.</p>
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<p dir="ltr"><em>Image: Getty Images</em></p>
