What Happens to a Monkey When Scientists Insert a Human Intelligence Gene?

It sounds like something out of Rise of the Planet of the Apes: scientists introducing a human intellect gene into monkeys.

But in a study that was published in March in the Chinese journal National Science Review, Chinese researchers succeeded in strengthening the monkeys’ short-term memories. Although other experts dismissed the impacts as insignificant, questions remain about where the research might go.

Monkey Brain Gene Research

The investigation, directed by geneticist Bing Su of the Kunming Institute of Zoology, sought to understand how the evolution of the human brain may have been influenced by the MCPH1 gene, which has been linked to brain growth. This gene is present in some form in all primates.

However, compared to other primates, humans have larger, more sophisticated, and slower-developing brains. The researchers wondered if these differences in the human version of MCPH1 might help to explain why humans have brains that are so much more complex.

Su and his team administered a virus containing the human form of MCPH1 to 11 rhesus macaque embryos. In comparison to transgene-free monkeys, the brains of the transgenic monkeys—those carrying the human gene—developed more slowly and more like those of humans.

Furthermore, the transgenic monkeys excelled and responded more quickly on short-term memory tests that involved matching colors and shapes by the time they were 2 to 3 years old. However, neither the size of the brains nor any other behaviors varied.

Ethics of Human Intelligence Gene Research

However, it’s not the findings that have the scientific community agog. Some people dispute the morality of introducing a human brain gene into a monkey, a procedure that bioethicist Rebecca Walker of the University of North Carolina claims could be the beginning of a slippery slope toward endowing non-human creatures with intellect similar to that of humans.

A geneticist at the University of Colorado School of Medicine named James Sikela and his coauthors pondered in a 2010 publication if a humanized monkey would integrate into society or endure harsh living conditions as a result of its altered genes.

Su and his co-authors made the claim that this kind of research on brain genes might shed light on social and neurodegenerative problems to support their work, but they don’t elaborate on what those applications would be. In the report, Walker adds, “I don’t really see anything that would lead me to believe that [the experiment] was necessarily a smart idea.

Su declined to comment for Discover but stated in an article for China Daily that “scientists believe that monkey models are sometimes irreplaceable for basic research, especially in researching human physiology, cognition, and disease.”

Additionally, the authors of the study claim that the “quite large evolutionary distance” (about 25 million years of divergence from humans) “alleviates ethical problems.” In terms of social and cognitive abilities, rhesus macaques are less similar to humans than primates like chimpanzees, which are more connected to us. Given the greater evolutionary gap, it would likely be more challenging to produce a macaque with human-like behavior.

But Walker rejects that justification. It is irrelevant when they split off from humans on the phylogenetic tree, according to her. They are referring to increased short-term memory, which would bring them somewhat closer to our level of cognitive functioning.

She believes that by influencing these skills, the endeavor is morally questionable and needs a more convincing rationale. Su said that even if the genomes of humans and monkeys are similar, there are still millions of genetic distinctions. A single precisely constructed research gene cannot cause significant change.

Studies on Human Genes

Sikela concurs that such a modification might be slight. However, he remains skeptical about the prospect of discovering a gene with a large impact on cognition.

Going along this road has some risky features, according to Sikela. One must consider the implications of where this is going and the appropriate approach to researching such issues.

Walker is concerned about the future of this work as well. Could these techniques be used to improve human brains? she queries. Despite the fact that she believes we are still far from there, she points out that science can move amazingly swiftly.

For instance, in China, twins’ genomes were edited in 2018 using the gene-editing method CRISPR, which at one point was thought to be far off from human study. (See page 32 for our No. 11 story of the year.)

Walker admits that conducting this research on primates “does feel concerning.” “And then perhaps considering how that might be applied to humans.”

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