Many of our closest relatives have long been unknown when it comes to their genetics. But now scientists have succeeded in decoding the genomes of almost half of all primate species. The resulting gene catalog provides new insights into the evolution of primates, unique selling points of humans and the genetic causes of human diseases. In the future, the collected data could be used to find pathogenic gene mutations, for example, and allow the associated diseases to be treated in a personalized way.
"Show me your friends and I'll tell you who you are." True to this motto, it can be immensely helpful for us humans to take a closer look at our closest primate relatives. Because by cracking their genetic code, we can learn more about them, but also more about ourselves and our evolutionary development. About what makes humans human and which gene mutations in our genome can trigger typical human diseases.
Baboons as a model for human evolution
Scientists from four international research teams have now taken a big step towards the goal of a complete primate DNA catalogue. They have succeeded in sequencing the genomes of a total of 809 monkeys from 233 species. This covers almost half of all existing primate species and has quadrupled the previous number of genomes available for this group in one fell swoop. The data obtained can now be used in various ways. Among other things, they have already given the scientists new insights into the evolutionary history of primates.
It has been shown, for example, that baboons could be a good model for the evolution of early human lineages inside and outside of Africa. Because, similar to our ancestors, there have been many instances of interbreeding, hydration, and gene flow between different closely related species throughout their evolution. According to current theory, the emergence of the first pre-humans and early humans can also be traced back to such a mixture of different species. "We found that baboons from western Tanzania are the first non-human primates to evolve from three genetic progenitor lines (species)," explains Liye Zhang from the German Primate Center. This means that the genetic structure of the baboon population and the history of gene exchange between the different species is far more complex than previously thought, but all the more useful for better understanding our own evolutionary history.
Gold mine for pathogenic gene mutations
However, the primate genetic data can also help us to better understand the unique selling points of being human. However, initial results indicate that we may not be as special as we thought: "With the new genome catalogue, the number of genomic variations that were assumed to only occur in humans has halved," explains Martin Kuhlwilm from the university Vienna. "The things that actually make us human seem to be rarer than expected."
Comparing primate genomes to our own has also identified 4.3 million mutations that may alter the function of proteins and thereby cause human disease. With the help of an algorithm based on deep learning, the researchers have already been able to filter out those mutations that are most likely harmless to us humans. According to this, six percent of the identified mutations are also common in primates. Since they do not get sick from it, they are probably also of little relevance to human diseases. However, as soon as it is clear which mutations are responsible for which diseases, this knowledge could eventually be used to develop personalized treatment concepts for individual patients.
Genetic diversity and endangerment
However, the new genome data also provide a first insight into the genetic diversity of our primate relatives. When there is a wide range of gene variants within a species' gene pool, this can increase a species' resilience. The greater choice increases the chance of successfully adapting to changing environmental conditions and pathogens. However, if the gene pool is impoverished, there is a risk of inbreeding and thus a reduction in genetic diversity, especially in small populations. The analysis of diversity therefore provides information as to which species most urgently need to be protected, at least from a genetic point of view – this is the conventional view.
The team led by Lukas Kuderna from the University of Pompeo in Barcelona therefore compared the genetic diversity of the primates examined and in particular the monkey species classified as endangered. There were large regional and family tree-related differences - but no clear connection to the endangerment of the monkey species. The scientists discovered that the lemurs of Madagascar, which are among the most endangered primate species in the world, have a relatively large genetic diversity. On the other hand, the eastern gorillas, which are also highly endangered, actually had a severely depleted gene pool.
Source: Deutsches Primatenzentrum GmbH – Leibniz Institute for Primate Research, University of Vienna; Specialist article: Science, doi: 10.1126/science.abn7829, doi: 10.1126/science.abn8153, doi: 10.1126/science.abn8197, doi: 10.1126/science.abl4997