Evolution is usually measured on the scale of millions of years. Now, scientists have found that primates might evolve far faster than other species, which calls into question when species diverged.
As primates evolved, the number of types of viruses tailored for targeting primates also multiplied. This held true as chimpanzees, Neanderthals and modern humans began to emerge. The APOBEC family of virus-fighting enzymes mounted a defense against these viruses, and bombarded the viral genome with clusters of mutations to cause them to be unable to continue an infection. These mutations, though, are risky for cells. This is largely because it could wreak havoc on our genome.
In this latest study, the researchers looked for the signature of past mutations in humans and our closest hominid relatives. They focused on one of the enzymes of the APOBEC family, called APOBEC3. This particular enzyme expanded into several subtypes during primate evolution, each with unique mutational signatures.
"What is appealing is that it's an accelerated evolutionary mechanism that could generate a large change in a gene in a single generation," said Erez Levanon, one of the researchers in the new study. "It's like playing the lottery - it could not have an impact, or it could have a major one."
The findings reveal a bit more about the evolution of primates. More specifically, it shows how evolution could have occurred more quickly than once thought.
"These events potentially mutate dozens of DNA bases in a small region less than the size of a gene," said Alon Keinan of Cornell University, one of the researchers. "It is reasonable to think that most of these mega-mutations will be deleterious and will disappear in evolutionary time, but we do see a large number that survived. Importantly, those that survived are overrepresented in functionally important parts of the genome, which suggests that some of these mutations have been maintained by natural selection because they conferred an advantage."
The findings reveal a bit more about how we evolved. More specifically, the study shows what mechanisms could have caused rapid mutation in primates over time.
The findings are published in the journal Genome Research.