Scientists at the University of California, San Diego created a Neanderthal brain rudiment (organoid) from stem cells using DNA data from an archaic person and the CRISPR genome editing system. The biologists' article has not yet been published in peer-reviewed scientific journals, but the researchers presented preliminary results at the university conference Imagination and Human Evolution. This is reported by Science Alert.
Geneticists inserted the Neanderthal gene - NOVA1 - into stem cells, from which they then grew pea-sized structures that mimic the cerebral cortex. NOVA1 is one of 200 protein-coding genes that differ between Neanderthals and modern humans. It plays a role in the early development of the central nervous system and is associated with autism and schizophrenia. The Nova-1 protein binds to messenger RNA and regulates its splicing - the excision of non-coding fragments (introns) from the nucleotide sequence and stitching of the rest. Sometimes, during alternative splicing, some of the coding parts of RNA (exons) are also cut out, which makes it possible to increase the number of protein products of one gene. However, only one base pair distinguishes Neanderthal NOVA1 from human.
Scientists have created pluripotent stem cells by reprogramming skin cells taken from people who do not suffer from autism spectrum disorders or neurological diseases. Using the CRISPR system, scientists replaced a base pair in NOVA1, creating a Neanderthal variant of the gene. They then weeded out cells with unwanted mutations as a side effect of editing. The development of the cerebral organoid took several months.
The resulting cerebral organelles - "neanderoids" - differed in the form and structure of neural networks from similar "mini-brains" in whose cells the DNA of Homo sapiens was located. So, they had fewer synaptic connections, and also had features characteristic of those who suffer from autism. According to the researchers, these differences influenced the ability of Neanderthals to socialize.
However, a number of researchers emphasize that cerebral organelles are a simplified model of normally developed nervous tissue and represent only an early stage of brain development. Thus, it is very difficult to determine the difference in the nervous activity of modern humans and Neanderthals.