A recent study has made it possible to accelerate the transformation of the monkey brain into the human brain. A human gene has been used to increase the number of neural stem cells. The experience can obviously be cold in the back and ethics was surely at the heart of the interruption of this research.
Will we ever see monkeys as intelligent as humans? This perspective naturally recalls the famous saga of the monkey planet. However, there is currently more talk about learning more about the evolution of the human brain. Proof of this is with this research published in the journal Science on June 18, 2020 and conducted by researchers from the Max Planck Institute of Molecular Cell Biology and Genetics in Desde (Germany), in collaboration with the Central Institute for Experimental Animals from Kawasaki (Japan).
German and Japanese scientists used marmoset embryos, in which they increased the size of the neocortex. In other words, the researchers hacked into the brain evolution of these primates. The main difference between great apes and humans is obviously in the brain, especially in terms of its size and structure. It is mainly about an expansion of the cerebral neocortex, at the center of cognitive functions. However, the latter is three times more imposing in humans than in the chimpanzee, its closest relative. So, the objective of the study in question was to understand how the neocortex could have undergone such an expansion and thus give us so much brain capacity.
Scientists worked on the ARHGAP11B gene, which is a mutation of the ARHGAP11A gene. This mutation occurred 1.5 million years ago, at the crossroads between humans and chimpanzees. From this separation come the Neanderthals, the Denisovans as well as the humans of today. The fact is that the gene in question codes for a protein that increases the production of neural stem cells.
For researchers, the mutation of this gene immediately influenced human evolution. In 2015, German researchers had already increased the production of brain stem cells in mice. However, it was a boosted version of the ARHGAP11B gene. This time, we are talking about an experiment on marmoset fetuses with the classic version of the gene.
Three to five days after ovulation, the researchers implanted the famous gene into embryos. Then, they grew during 101 days before interruption, fifty days before natural birth.
According to scientists, three major developments have resulted from the presence of the gene. First, there is an increase in the size of the neocortex (see below) and a pleated configuration. This configuration usually allows the human brain to develop considering the reduced size of the skull. Finally, there is talk of an increase in the number of neuron progenitor cells. These cells are very important in the cerebral evolution of monkeys.
Rest assured, creating monkeys as intelligent as humans is still science fiction. Besides, to avoid any scandal, the researchers stopped their research and did not want to work on monkeys too close to humans (chimpanzees or macaques).
Finally, the reason for the interruption is also found elsewhere. The lack of knowledge regarding behavioral changes resulting from the modification of the neocortex made a possible termination of birth an irresponsible act.