The sciences have brought great advances in fields like medicine and longevity, as well as great tragedies, like the atomic arms race, to our world. When researching this piece, a line in the film Jurassic Park that came to mind: “Your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should.”
In 2019, scientists in China experimented with improving the short-term memories of monkeys by injecting them with human genes. Some scientists have been alarmed by the experiment, which conjures memories of films like “Planet of the Apes.” Other experts believe that the results of these experiments will be minor. The study was published in the Chinese journal National Science Review.
Bing Su, a geneticist from the Kunming Institute of Zoology has led the research team responsible for the experiment. They wanted to investigate how MCPH1, a gene linked to brain size , contributes to the evolution of the brain in humans. All primates carry the MCPH1 gene, but as is well known, the human brain is the largest and more advanced brain of all species of primate, and it develops the slowest. Researchers wanted to pinpoint whether MCPH1 can explain why our brain is more complex than any other primate.
The team, lead by Su, injected 11 rhesus macaque embryos with a virus carrying the human version of MCPH1. A control population of macaque embryos were not injected with the virus carrying the gene. The researchers found that the brains of transgenic monkeys who received the human version of MCPH1 developed more slowly, as you would see in a human. By the age of three, the transgenic monkeys performed better on short-term memory tests, like matching colors and shapes, than the control monkeys without the human gene.
Scientists observed no other differences in brain size or behavior.
Su’s research team’s findings are interesting, but some in the scientific community are questioning the ethics of putting a human brain gene into a monkey. Rebecca Walker, a bioethicist at the University of North Carolina, believes that experiments like these could lead to a slippery slope of attempting to give animals human intelligence.
But Su believes that his work is justified and could help provide insights into neurodegenerative and social disorders in humans. Still, Walker is skeptical.
“I don’t really see anything in the paper that would make me think that [the experiment] was necessarily a good idea,” she said.
In an interview with China Daily, Su told that publication that there was little need for concern. “Scientists agree that monkey models are at times irreplaceable for basic research, especially in studying human physiology, cognition and disease,” he said. In the paper, researchers note that “relatively large phylogenetic distance (about 25 million years of divergence from humans) … alleviates ethical concerns.”
Because of this evolutionary distance of 25 million years, it would be extraordinarily difficult for a macaque to be engineered to behave at all like a human. But Walker feels this detail is largely irrelevant.
“It doesn’t really matter when they became differentiated from humans on the phylogenetic tree,” she said. “They’re talking about improved short-term memory, which would be putting them sort of closer to us in terms of those cognitive abilities.”
Still, Su believes there’s little to worry about.
“While monkeys and humans have similar genomes,” Su told the China Daily. “There are still tens of millions of genetic differences. Changing one gene carefully designed for research will not result in drastic change.”