A team of researchers has managed to develop mini-brains similar to those of Neanderthals in a laboratory, exchanging a single human gene for an ancient variant thanks to the magnificent CRISPR technique.
Yes indeed; The authors of the study point out that the organoids they produced should not be considered true Neanderthal brains, but are rather like droplets of neurons that possess the genetic characteristics of this species of extinct hominin.
Neanderthals and Denisovans are some of our closest relatives. They lived alongside us about 50,000 years ago when modern humans migrated from Africa to Europe, but they became extinct shortly after we came into contact with them. The reason, we do not know.
Brains do not fossilize , so there is no physical record to study.
Because the scientists wanted to know more about how our brains differed from these other hominins and whether this could affect survival, they compared the genomes of modern humans, Neanderthals, and Denisovans, finding a total of 61 genes that differed. Of these altered genes, which separated the species, one in particular caught their attention: the ventral neuro-oncological antigen 1 (NOVA1).
This gene has been associated, in humans, with various neurological disorders such as autism or schizophrenia.
They decided to employ stem cells, a tool not often applied in evolutionary reconstructions that can be used to build brain organoids, in this case “mini brains”, in a laboratory dish. Mimicking that unique alteration they found in a gene, the researchers used stem cells to engineer “Neanderthal” brain organoids.
As these mini brains matured, ancient human organoids were smaller in diameter, had a more wrinkled cell surface, and their cells multiplied more slowly than those of modern humans. ” They are quite different from modern humans, suggesting that the alteration of a single base can change the development of the brain,” says Muotri, leader of the work that publishes the journal Science. “A baby chimpanzee can be smarter than a human newborn. We need time to raise our babies until they become independent. We don’t see that in other species. I think what we’re seeing here is something similar.”
This alteration also changed the expression of 277 genes compared to modern human organoids, and caused 113 alternative splicing events, a process that causes a gene to encode multiple proteins, many of which are related to brain development and formations. synapse (communication between neurons).
Expression of the archaic variant also led to altered synaptic protein interactions and neurotransmitter signaling, and prevented neurons from synchronizing in networks.
The researchers conclude that “the specific human substitution in NOVA1, which was fixed in modern humans after the divergence of Neanderthals, may have had functional consequences for the evolution of our species. We do not know exactly how and when in our evolutionary history it occurred. That change . But it seems to be significant and could help explain some of our modern capacities in social behavior, language, adaptation, creativity and use of technology. “
Referencia: “Reintroduction of the archaic variant of NOVA1 in cortical organoids alters neurodevelopment” by Alysson R. Muotri et al. Science
