Chinese researchers have created transgenic macaques that are a little more "human" than their fellow monkeys. Placed in front of a window the size of their arm, these genetically modified monkeys were more successful than normal monkeys at grabbing food placed in hard-to-reach spots. Further tests show that the gene added to their genome, SRGAP2C, is indeed involved in brain development. The study, led by Professor Su Bing of the Kunming Institute of Zoology in Yunnan province and part of the Chinese Academy of Sciences, was published in November 2023 in a Chinese scientific journal.
This is the second study by this team to test the influence of adding the human version of a gene expressed in our brain on non-human primates (NHPs). In 2019, it made headlines with an experiment involving another gene, MCPH1, whose dysfunction in humans causes microcephaly. Already then, the transgenic macaques experienced slower brain development, in line with that observed in humans, but showed superior memory to their unmodified counterparts. This spectacular result set off alarm bells among some Western ethicists. According to Bing, this research provides a better understanding of the millions of years of evolution that have enabled humans to distance themselves from apes.
In this field of genetic modification of NHPs, China is ahead of the game. It's the same story for cloning: On January 15, a team from the Shanghai Neuroscience Institute published an article explaining the success of a new cloning technique that led to the birth, two years ago, of a rhesus macaque, which is still alive. Chinese biologists believe they have identified a way to improve the success of cloning procedures. Since the cloning of Dolly the sheep in 1996, the success rate of such procedures has been low: from 1% to 3% for most species and from 5% to 20% for livestock.
For scientific research, transgenesis and cloning are promising tools. Having cohorts of monkeys with identical genomes, like laboratory mice, is advantageous. And by modifying their genes, we can better understand both evolution and, potentially, certain human diseases.
"Monkeys have an irreplaceable role to play in the study of central nervous system function and neurological diseases such as Parkinson's and Alzheimer's," said Bing. However, Bing believes that research is not yet ready to produce lines of macaques with "humanized" brains. "The first question is ethical: I don't think it's appropriate to edit certain genes, such as those involved in language development, for example. For the moment, we have carefully selected the genes we are modifying. Then there are technical obstacles. Despite the Crispr-cas9 tool, editing the monkey genome remains very difficult."
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