A new study suggested that human evolution could turn our saliva venomous in the distant future. Researchers from Okinawa Institute of Science and Technology Graduate University found that genetic foundation required for oral evolution is present both in mammals and reptiles, hence, humans could spit venom too in future.
The scientists looked for genes that work alongside and interact with venom in pit viper snakes and eventually, the study found the molecular link between venomous glands in snakes and salivary glands in mammals.
Agneesh Barua, first author of the study, talking to Daily Mail said “venoms are a cocktail of protein that animals have weaponized to immobilize and kill prey as well as for self-defence.” Venom has arisen in different animals like spiders, scorpions, jellyfish, snakes and some mammals and way of delivery, an oral system, is the most common in all of them.
Previous studies have focused on genes that code for proteins but in this study, scientists researched how different genes interact. Barua explained they looked at genes that were present before venom’s origin enabling the formation of venom systems.
The team studied the venom of Taiwan habu snake and identified around 3,000 glands that play a vital role in protecting cells from stress by producing lots of proteins.
Barua said this is the first evidence supporting the theory that venom glands evolved from early salivary glands.
Scientists also studied the salivary glands of mammals and found that their genes had a similar pattern of activity to that seen in snake venom glands, therefore, they believe that salivary glands in mammals and venom glands in snakes share an ancient functional core which was split hundreds of millions of years ago.
Barua said snakes incorporated “many different toxins into their venoms and mammals like shrews produce a simpler venom that has a high similarity to saliva.”
It was found after some experiments conducted in the 1980s that “male mice produce compounds in their saliva that are highly toxic when injected into rats,” he revealed.
We might encounter venomous mice in a few thousand years if they have a better reproductive success under right ecological conditions, Barua added.
He emphasised that in right ecological conditions, humans too could become venomous, giving a whole new meaning to “toxic person”, he joked.