The last common ancestor of humans and chimpanzees roamed the planet about seven million years ago. That might sound like a lot, but it’s roughly the same distance that separates African elephants and Asian elephants, two species so similar they’re often just called elephants. Biologist Tomàs Marquès Bonet is working to answer one of humanity’s great questions: what makes us human, what happened in those seven million years for humans to be able to walk on the moon and the rest of the primates are still on the branches of the moon trees lives? . A big step was taken this Thursday. An international consortium led by Marquès Bonet has read the DNA of 233 primate species, half of all known species. This monumental genetic information is used to clarify what a human being is, but also to elucidate the origin of a variety of diseases, such as cancer.
A person’s genome, their DNA, is a text of more than 3,000 million chemical letters with instructions so that each cell knows what to do. “If we sequence the DNA of a sick person, we will find thousands of candidate mutations associated with this disease,” explains Marquès Bonet from the Institute of Evolutionary Biology in Barcelona. The researcher says that five years ago, the US company Illumina, world leader in DNA sequencing technology, proposed to coordinate a macro project to read the genomes of hundreds of primate species with the aim of developing a genetic catalog which would allow the identification of the specific variants of human diseases. Their findings will be published this Thursday in a special issue of the journal Science.
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“If you see a mutation in a patient and you find it in different primate species, rule it out because it’s certainly not the cause of the disease. On the other hand, if you find a mutation that only occurs in tumor tissue and has never been seen in any other primate, that mutation must be causing something disruptive in the cell and is a perfect candidate to pull the thread further,” says Marquès. Bonet.
The consortium analyzed the DNA of more than 800 individuals from 233 species, including those closest to humans – chimpanzees, gorillas and orangutans – and some that are critically endangered, like the Sahafary jumping lemur, of which only 40 copies are left in Madagascar. The researchers used this data to train an algorithm that detects disease-associated mutations. According to a study by the UK Biobank, a biomedical data registry involving nearly half a million volunteers, this new artificial intelligence tool has uncovered 73% more links between genetic variants and pathologies.
Tomàs Marquès Bonet, Alejandro Valenzuela, David Juan, Esther Lizano and Arcadi Navarro, co-authors of the study, at the Institute of Evolutionary Biology in Barcelona.IBE and UPF
“We have used the algorithm in complex diseases such as diabetes and cancer, where the cause is obviously not a mutation in a gene, but a combination of many things,” explains Marquès Bonet. “There are common mutations that contribute, as has been observed so far, but for the first time we can say that there are rare, rare mutations that have a very large impact on these complex diseases.” And that’s one with us Algorithm trained by primates succeeded,” emphasizes the biologist. His institute is a joint center of the Higher Council for Scientific Research (CSIC) and the University of Pompeu Fabra.
Marquès Bonet explains that when the project began five years ago, the genomes of only a few dozen primate species had been sequenced. “The jump from 20 to 233 is a huge increase that allows us to better filter what is uniquely human and what isn’t. Basically, we halved the candidate mutations to define our species,” affirms the researcher. His team has discovered 89 variants in 80 genes that are crucial to explaining what a human is. As an example, Marquès Bonet cites the NOVA1 gene, which acts as an orchestra conductor in early brain development.
16% of the human genome resembles the gorilla genome more than that of chimpanzees
Iker Rivas González, bioinformatics specialist
Chimpanzees and humans parted ways more than seven million years ago. According to Iker Rivas González, a bioinformatician at Aarhus University, Denmark, the gorilla group left the common path earlier, around eight million years ago. “However, about 16% of the human genome is more similar to the genome of gorillas than that of chimpanzees,” says Rivas González, who leads one of the eight studies published in the special issue of Science. Rivas González’s team is studying this phenomenon, which causes parts of the same genome to have different evolutionary histories. His group found that there are genes related to fur or the immune system that evolve faster than other genes in primates.
Primatologists around the world look to monkeys for clues to human social development. Julia Fischer from the German Primate Center is studying sea baboons, 15-kilo African monkeys with a unique behavior: females choose a male of their choice and no longer mate with any other. The males, meanwhile, are waiting to be chosen by one or more females and mate with all of them. The question is to what extent these behaviors are embedded in the DNA.
“That’s an absolutely fantastic question,” confirms Marquès Bonet. More than a decade ago, his group participated in the first sequencing of the genomes of chimpanzees and bonobos. The former form very violent patriarchal groups, while the bonobos form peaceful matriarchal societies that use sex to resolve conflicts. “So we look for areas of the genome that are related to these behaviors and we don’t find them, but that doesn’t mean they’re not there,” he admits. The flood of primate data is now opening the door to new discoveries.
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