Genetics shows how humans are close to mammals – 04/27/2023 – Science

Scientists released on Thursday (27) the results of a project that compares the genomes of 240 species of mammals – from anteaters to zebu and zebra, even humans – to track evolutionary changes over 100 million years, identifying traits widely shared genetic traits and those more uniquely human.

Findings from the ambitious Zoonomia Project have identified functionally important parts of the genome in people and other mammals and have shown how certain mutations can cause disease. The project revealed the genetics of unusual mammalian traits, such as hibernation, and showed how widely the sense of smell varies.

The researchers said findings about the genetics of hibernation could help inform human therapies, critical care and long-distance spaceflight. Zoonomia’s findings could also help identify genetic mutations that lead to disease, with one study examining patients with a type of brain cancer called medulloblastoma.

“We are leveraging the fact that there is enormous biodiversity on this planet to really understand ourselves and make new discoveries relevant to the treatment of human disease,” said Elinor Karlsson, director of the Vertebrate Genomics Group at the Broad Institute of MIT and Harvard and co-leader of the international consortium of researchers.

“The human genome was sequenced more than 20 years ago, and despite that, it is still very difficult to understand what the functional elements are,” added consortium co-leader Kerstin Lindblad-Toh, professor of comparative genomics at the University of Uppsala, Sweden. .

The findings, detailed in 11 studies published in the journal Science, involved placentals, by far the world’s most common mammalian assemblage known for giving birth to well-developed babies, not egg-laying monotremes or pouched marsupials.

The project examined most of the existing mammalian lineages, although they make up only 4% of the species. They vary in size from the 18 meter long North Pacific right whale to the 3 cm long bee bat. Our closest evolutionary relatives—chimpanzees and bonobos—were included, along with the western lowland gorilla and the Sumatran orangutan.

Cats include the cheetah, Siberian tiger, jaguar, leopard and the humble house cat. The canines have one celebrity among them—Balto, the Alaskan sled dog famous for bringing life-saving medicine in 1925 to the town of Nome. The most primitive species was the insect-eating solenodon, closely related to mammals alive during the age of dinosaurs.

The researchers identified genomic elements —4,552 in all— that were virtually the same across all mammals and were identical in at least 235 of the 240 species, including humans.

“Many of these elements are located near genes involved in embryo development — a process that needs to be tightly controlled to result in the development of a healthy, functioning animal,” said Uppsala University evolutionary geneticist Matthew Christmas, lead author of a of studies.

In terms of differences between humans and other mammals, the study pointed to regions associated with developmental and neurological genes. This suggests that the evolution of specific human traits since our species homo sapiens diverged from a common ancestor with chimpanzees, perhaps between 6 and 7 million years ago, involved changes in the regulation of genes in the nervous system.

“This makes sense, as some of the biggest differences between us and our ape cousins ​​are in our ‘brain power’ and cognition. It seems that much of what makes us human comes down to tweaks in the way our neurological genes are regulated, rather than any major change in the genes themselves,” said Christmas.