If you want to study a Neanderthal's brain, you would think you're out of luck. Only the bones of our extinct ancestral humans remain, so it's hard for us to grasp how they were wired some 40,000 years ago.
The solution: make your own Neanderthal mini brain in a petri dish.
That's what Alysson Muotri, a geneticist at the University of California, San Diego (UCSD), and his team have done, recently describing Neanderthal "organoids" at a UCSD conference, reports Science Magazine.
"We're trying to recreate Neanderthal minds," Muotri told Science.
Traditionally, scientists working to unravel the mysteries of normal human physiology and disease use cell suspensions and cultures, producing 2D or 2.5D planes and sheets of cells. Using stem cells to build organoids provide researchers with miniaturized 3D models of an organ, allowing for more detailed research into pathologies and cellular biology.
By combining ancient DNA extracted from Neanderthals, stem cells and the gene editing technique CRISPR, Muotri's team is able to create the "Neanderoid" mini brains. As they're "lab-grown", the mini brains receive the nutrients required to stay alive through diffusion in a petri dish, rather than through a blood supply.
There are around 200 protein-coding genes that differ between humans and Neanderthals, so Muotri focused in on one specific gene called NOVA1, which plays a role in neuronal development. It has also been linked to conditions such as schizophrenia and autism. The gene is highly conserved between humans and Neanderthals, with just a single base pair difference in DNA.
Switching in the Neanderthal version of the gene using CRISPR allows the researchers to compare the Neanderoids with their human brain organoids. They've already noted some stark differences. The cells in the mini Neanderthal brains made less synaptic connections and though Muotri didn't want to compare autistic kids with Neanderthals, he noted that this abnormal network of brain cells did resemble what he has seen in the development of brain cells in children with autism.
In a both fascinating and terrifying twist, Muotri's team have already created human brain organoids and can detect electrical signals coming from the tissue. The next step is to wire those mini brains to crab-like robots, develop the Neanderoids to the point where they can do the same and pit them against each other.
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