What Are Primates? Genome Study Offers Clue on What Makes Us Humans

According to the Theory of Evolution, animals such as apes, lemurs, and monkeys are human's closest relatives, evolving from a common ancestor over the past 60 million years. Since primates are related, they are genetically similar. Understanding the nature and characteristics of these groups of animals can give us more insight into humans.

What are Primates?

Primates refer to a diverse group of mammals divided into the strepsirrhines (lorisids, galagos, and lemurs) and haplorhines (humans, apes, monkeys). These ancient eutherian groups were believed to have originated 85-55 million years ago from small terrestrial mammals.

Scientists assume there are 376 - 524 species of living primates, depending on the method of classification used. These animals share the same characteristics: large brains, long life spans, slow growth, and complex social groups. They are also known for their hands, which have adapted for grasping. Unlike other animals, a primate's vision tends to be more important than its sense of smell. Additionally, they give birth to few offspring, usually one at a time.

Most primates live in the tropical or subtropical region, although a few also inhabit temperate areas. Primates are arboreal or tree-dwellers, except for a few terrestrial species. Some members of this group eat leaves or fruit, while others are either insectivorous or carnivorous.

Genome Study on Primates

In a comprehensive genomic study conducted on primates, a team of researchers sequenced and analyzed the genomes of 233 species of primates, including half of those alive today. This research explored the origins of primates as a group. It also covered some of the most endangered primates, such as the Western black crested gibbon found in China, Laos, and Vietnam and the northern sportive lemur, which thrives north of Madagascar.

Led by genomicist Lukas Kuderna from Barcelona Biomedical Research Park's Institute of Evolutionary Biology in Spain, the team adjusted the timeline for the divergence of the evolutionary lineage that led to humans and the one that led to chimpanzees and bonobos. They discovered that this milestone occurred 6.9 to 9 million years ago, slightly longer than previously estimated.

The result of the study has revealed that primates have greater genetic diversity than humans. A vast majority of primate species have more genetic variation per individual than do humans. This indicates that there were likely multiple population bottlenecks, which altered the amount and nature of genetic variation in ancient human populations.

Some genetic variations previously thought to be exclusive to humans were also found in other species of primates, but scientists focused on other characteristics that were uniquely human. In this study, primate genomes were used to train an artificial intelligence algorithm to predict genetic mutations that can cause human diseases.

The genome data has played an important role in identifying the primate species that most need conservation efforts. However, genetic diversity was a poor predictor of overall extinction risk. According to Kuderna, this could be because the populations of various primate species have declined so quickly that their genetics did not have time to catch up and adjust to the loss in population size.