Human gene enlarged monkey brains

And if thanks to manipulations genetic the monkeys became as intelligent as humans, competing with them as in Planet of the Apes? The subject has fascinated scientists for years, and a new experience brings us a little closer to Pierre Boule's book adapted for cinema in 1968. German and Japanese researchers say to have "hacked" the evolution of brain by increasing the volume of neocortex at embryos of marmosets.

The human brain, the result of a slow evolution from the monkey

Seven million years separate the great apes from the first Homo sapiens. A slow evolution which has notably resulted in an increase in brain size, and a modification of its structure, with in particular an expansion of the cerebral neocortex. The latter, the youngest part of the cortex during evolution, is about three times the size of our closest relative, the chimpanzee. It is at the center of cognitive functions such as reasoning or language. One of the key questions for scientists is how the neocortex got so large and gave us our cognitive abilities.

One small DNA letter that makes all the difference

In the study published today in the journal Science, Wieland Huttner and colleagues from Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), based in Dresden, Germany, were interested in uncomfortable ARHGAP11B. The latter is the result of a mutation in the ARHGAP11A gene, which occurred about 1.5 million years ago along the evolutionary line that led to Neanderthals, Denisovians and humans today , after this line separated from that of the chimpanzee. This gene codes for a protein known for its ability to increase the production of stem cells neurons.

" The mutation in the ARHGAP11B gene of a single genetic letter, namely the passage from a C to a G, results in the loss of 55 nucleotides in the formation ofARN corresponding messenger. This leads to a change in the transcription of amino acids in protein, explains Wieland Huttner. This mutation seems to have immediately influenced human evolution Adds the researcher. In 2015, Huttner had succeeded in increasing the production of brain stem cells in mice, but with a “boosted” version of the gene. This time, German researchers have teamed up with the Central Institute for Experimental Animals (CIEA) at Kawasaki and Keio University in Tokyo, pioneers in the generation of transgenic monkeys, to conduct an experiment with fetus marmoset with the normal version of the human gene.

A bigger, more folded brain

The gene was implanted in marmoset embryos three to five days afterovulation. They then allowed the embryos to grow to 101 days of age, 50 days before the normal date of birth. They were thus able to contact three major developments in the cerebral development of monkeys:

• an increase in the size of the neocortex;
• a fold configuration (convolutions), which allows humans to increase the size of the brain while keeping within the restricted volume of the brain cavity ;
• an increase in the number of progenerative cells neurons, specifically those of the upper layer, those who play an essential role in brain development in primates.

Draconian ethical precautions

From there to create monkeys as intelligent and competing with humans, the step is far from being taken. However, to avoid any controversy, the researchers took care to surround themselves with all ethical precautions. There is no question here of working on macaques or chimpanzees, which are far too close to humans, nor of carrying out the birth of genetically modified monkeys. Wieland Huttner also implies criticism of the Chinese experience. " Completing the birth of marmosets would have been irresponsible, because we do not know the behavioral changes induced by the modification of the neocortex ", Judges the researcher. We will not know for the moment if these marmosets could have played chess with us.

A human brain gene implanted in monkeys

AFP-Relaxnews article published on 04/20/2024

Chinese researchers have introduced a human version of a gene involved in brain development into macaques. Although the experiment was not frankly conclusive, it will not fail to cause new controversy after the affair of genetically improved babies.

Chinese scientists implanted gene thought to play a role in human brain development in monkeys as part of a study into the evolution ofintelligence human. Appeared in March in the English publication National Science Review from Beijing, This study was carried out by researchers from the Institute of Zoology in Kunming (southwest of China) and the Chinese Academy of Sciences in collaboration with American researchers from the University of North Carolina.

The researchers implanted 11 rhesus macaques human versions of the MCPH1 gene, which scientifically believe play a role in the development of the human brain. The brains of these monkeys, like that of humans, took longer to develop; the size of their brains was not superior to that of their control group counterparts. Only five of them survived to the testing phase, where they had to remember colors and shapes on a screen and at MRI. According to the researchers, the modified animals performed better on short-term memory tests with better reaction time compared to monkeys living in the wild.

"We meet on The Planet of the Apes "

" Our results show that non-human transgenic primates (apart from cash great apes) have the potential to provide important insights into fundamental questions about what makes humans unique Write the authors of the study. According to them, the rhesus macaque, although closer genetically humans that rodents, remains far enough from humans not to raise ethical questions, but that did not deter critics. " In popular imagination, we simply find ourselves on The Planet of the Apes "Commented Jacqueline Glover, a bioethicist from the University of Colorado. " To humanize them is to do something wrong. Where would they live and what would they do? We must not create a living being that cannot have a meaningful life in any context "She told the MIT Technology Review. Larry Baum, a researcher from Center for Genomic Sciences from the University of Hong Kong, nevertheless put these fears into perspective, stressing that this study only modified one of the 20,000 genes of the macaque.

Genetic manipulations that raise questions

This experiment is the latest in a series of Chinese biomedical research that has sparked ethical controversy. In January, a team of scientists announced that they had cloned five monkeys from a unique specimen whose genes had been modified to make him sick, in order to study the sleeping troubles. They had discovered that these monkeys were showing signs of associated mental problems (depression, anxiety, behavior related to schizophrenia). These results published in the National Science Review were intended to serve research on human psychological illnesses. In November 2018, Chinese researcher He Jiankui boasted of having gives birth to two human babies whose genes had been modified to protect them from virus of AIDS. Much criticized by Beijing and the international scientific community, he found himself at the center of a police investigation and was dismissed from his duties at the University of South China where he officiated.