What the Largest-Ever Study of Primate DNA Reveals About Ourselves

A new, massive catalog of primate genomes is painting an ever-clearer picture of the group’s evolutionary tree—and humans’ place in it.

In a collection of papers published this month in the journals Science and Science Advances, researchers sequenced the genomes of 809 individuals from 233 non-human primate species—a diverse group of creatures that spans nearly half of the total 521 recognized primate species.

The data have already revealed a slew of findings on primate evolution, conservation, health and disease—and they’re also shedding light on specifically human traits.

“This massive sample will ultimately spark new and unexpected research directly relevant to human origins,” Luis Darcy Verde Arregoitia, a mammalogist at the Mexico Institute of Ecology who did not contribute to the research, tells Science’s Elizabeth Pennisi.

“The more we understand about primate genomics, the more we’ll understand about human genomics,” Alison Behie, a primatologist at the Australian National University, tells Nature News’ Dyani Lewis. “There’s a potential there to do a lot more really interesting work as they grow that sample size to bring in more species.”

Primates share a few key characteristics, including large, complex brains, forward-facing eyes, grasping hands and long childhoods, according to the Australian Museum. Still, they are the third most diverse order of mammals after rodents and bats, with species ranging from siamangs and tarsiers to lemurs, gorillas, orangutans and chimpanzees.

The last common ancestor of all living primates roamed the Earth around 60 million years ago. With the new research, scientists found that the lineage that led to humans split off from the one that led to chimpanzees and bonobos between 6.9 million and 9 million years ago, writes Reuters’ Will Dunham.

Using the genomes, the researchers studied a number of questions related to modern human health. They looked at 4.3 million common genetic variants present in humans and measured how widespread they were in other primates’ DNA. From that analysis, they suggest that about 98.7 percent of the variants are likely not damaging to humans, according to Nature News.

Researchers also described a new artificial intelligence algorithm called PrimateAI-3D, which has been trained on genomes to determine whether these human gene variants could be damaging or benign, per the Washington Post’s Mark Johnson.

“Studying primate genomic diversity is not only important in the face of the ongoing biodiversity crisis, but also has huge potential to improve our understanding of human diseases,” Lukas Kuderna, a researcher involved in the work and a genomicist at the Barcelona Biomedical Research Park’s Institute of Evolutionary Biology in Spain, tells Reuters.

While previous research has looked at primate genomes, it has included only a relatively small number of species and few wild-born primates, according to one of the studies. Five years ago, scientists had only sequenced less than 10 percent of primate species, Dong-Dong Wu, an evolutionary biologist at the Chinese Academy of Sciences who contributed to the work, tells Nature News. Now, with this new research, scientists have data on 47 percent of primate genomes.

But gathering all the information was a logistical challenge—the teams took blood samples from hundreds of wild and captive primates. Around 72 percent of the individuals were wild-born, and 58 percent of the represented species are classified as threatened with extinction, making them even harder to find and study.

“It takes an enormous amount of time, effort and government permits to obtain genetic samples of wild primates,” Paul Garber, a biological anthropologist at the University of Illinois Urbana-Champaign who wasn’t involved in the research, tells Science. And gaining access to captive species proved challenging as well, requiring permission from local officials.

Today, primates are at risk, especially due to habitat loss. About 60 percent of primate species are threatened with extinction, and around 75 percent are experiencing population decline, per the new research.

Most primate species have more genetic diversity than humans do, according to the new findings, which is, in general, thought to improve survival chances by reducing inbreeding.

But a primate’s risk of going extinct is not connected to its genetic diversity, the scientists found. “The population declines are so rapid that genetics does not manage to catch up with it,” Katerina Guschanski, one of the project’s researchers and an evolutionary biologist at the University of Edinburgh, tells Science.

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Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.