According to a new study, humans have the tools to eventually evolve into a venomous species, although the chances are very low. The study revealed that mammals and reptiles have the tools to produce venom in their salivary glands and that’s how over 100 non-venomous animals turned into venomous creatures.
Interestingly, mammals use their venom in different ways. Vampire bats use their toxic saliva to prevent blood clots and easily feed from wounds. Venomous shrews and shrew-like solenodons use their venom to overcome larger creatures and occasionally even paralyze their prey so they can come back at a later time to feed on them. While platypuses don’t have venom in their saliva, they do have venomous spurs on their back legs that they use as a defense mechanism.
Slow lorises are the only known venomous primate species. Their bite is so powerful that it can cause flesh to rot, but they only use their venom on each other instead of other animals.
So, will humans become like slow lorises or even venomous snakes and spiders? Agneesh Barua, who is a doctoral student in evolutionary genetics at the Okinawa Institute of Science and Technology in Japan as well as a co-author of the study, answered this by saying, “Essentially, we have all the building blocks in place,” adding, “Now it's up to evolution to take us there.”
Barua and Alexander Mikheyev, who is an evolutionary biologist at Australian National University and a co-author of the study, focused on “housekeeping” genes related to the venom instead of looking just at the toxins. By studying a brown pit viper called Taiwan habu (or Trimeresurus mucrosquamatus), they found that numerous genes are common in amniotes (animals that fertilize their eggs internally or lay them on land) and that many of the genes have folding proteins – venomous creatures create toxins that contain protein.
There are large amounts of protein in human saliva as well. Specifically, kallikreins (stable proteins that digest other proteins) are found in saliva and are present in several venoms. Bryan Fry, who is a biochemist and venom expert at The University of Queensland in Australia but was not involved with the study, stated, “It's not coincidental that kallikrein is the most broadly secreted type of component in venoms across the animal kingdom, because in any form, it's a very active enzyme and it's going to start doing some messed-up stuff.”
With that being said, the researchers did note that it is unlikely that we’ll turn into venomous creatures unless something drastic happens where we have to evolve such a feature. Ronald Jenner, who is a venom researcher at the Natural History Museum in London but wasn’t involved with the study, reiterated this by telling Live Science that venom usually only evolves as a defense mechanism or for capturing prey.
The study was published in the journal Proceedings of the National Academy of Sciences where it can be read in full.