A new scientific article suggests that human evolution could make our saliva toxic. At least in the distant future. In their study, published March 29 in the journal Proceedings of the National Academy of Sciences (PNAS), the researchers claim they have discovered that the genetic basis necessary for oral evolution is present in both reptiles and mammals. This suggests that humans might one day evolve to spit out venom like snakes.
“All basics available”
This study is the first to provide strong evidence of the molecular link between venom glands in snakes and salivary glands in mammals. “Essentially, we all have the building blocks,” said study co-author Agneesh Barua, a graduate student in evolutionary genetics at the Okinawa Institute of Science and Technology in Japan.
“Now everything depends on the development,” he said, reports the site syfy. Many of the toxins present in venom are identical in very different animals, including spiders, snakes, and slow loris (the only known poisonous primate species).
Several thousand genes identified
However, Barua and his colleagues are not focusing on the toxins themselves. Instead, the team, including Australian National University biologist Alexander Mikheyev, studied the genes responsible for regulating the entire system that produces the toxin. As part of their research, the scientists examined the venom of the Habu snake from Taiwan. This enabled them to identify around 3,000 genes.
Scientists have studied the venom of the Habu snake in Taiwan. Photo Credit: Shutterstock / Joe McDonald
They later discovered that these played an important role in protecting cells from stress caused by the production of proteins. Surprisingly, similar genes have also been found in mammals such as humans, chimpanzees, and dogs.
Humans also produce proteins that play the same role. Known as kallikreines, these are a key component of many poisons. “While snakes are very adept at incorporating a wide variety of toxins into their venom and increasing the number of genes involved in the production of venom, mammals such as shrews produce a simpler venom that is very similar to saliva.”, Said Barua.
The OIST PhD student added that, given the right environmental conditions, humans could “one day” develop poison. However, many experts consider this to be unlikely.