Humans could have toxic saliva like snakes soon: Shocking study claims they have the genetic ability to do so

Humans and other mammals have much more in common with our slithering friends than we think

Salivary glands in mammals and venom glands in snakes share an ancient functional core (Getty Images)

Ever wanted to stay away from 'toxic people' so as not to become toxic yourself? Research says, over time, it may not be in your hands.

Humans, like all other creatures, have evolved to their present stage and continues to evolve. A new study claims that at some point in the distant future, our saliva may become venomous, similar to that of a snake. Now while it's highly unlikely that people will join rattlesnakes and platypuses among the ranks of venomous animals, the study reveals that humans do have the tool kit to produce venom — in fact, all reptiles and mammals do.


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Researchers at the Okinawa Institute of Science and Technology Graduate University in Japan looked for genes that work alongside and interact with venom in pit viper snakes, which are a subfamily of venomous vipers found in Eurasia and the Americas.

Their findings stated that the genetic foundation required for oral venom to evolve is present in both reptiles and mammals, suggesting human beings could evolve to spew venom, reported the Daily Mail. In a first, concrete evidence of an underlying molecular link between venom glands in snakes and salivary glands in mammals, was found. The collection of flexible genes, particularly those associated with our own salivary glands, explains how venom has evolved independently from our nonvenomous ancestors more than a hundred times in the animal kingdom, Live Science says.

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'A cocktail of proteins, weaponized'

"Venoms are a cocktail of proteins that animals have weaponized to immobilize and kill prey, as well as for self-defense," said first author, Agneesh Barua. "What's interesting about venom is that it has arisen in so many different animals: Jellyfish, spiders, scorpions, snakes and even some mammals." Barua, a doctoral student in evolutionary genetics, said that essentially, we have all the building blocks in place. "Now it's up to evolution to take us there." He added: "Although these animals evolved different ways to deliver venom, an oral system — where venom is injected through a bite — is one of the most common."

Biologists have known that oral venom glands are modified salivary glands, but the new research reveals the molecular mechanics behind the change. They looked at how different genes interact. "We needed to look at the genes that were present before venom's origin, genes which enabled the rise of venom systems," said Barua.

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We share an ancient functional core

The team took to studying venom from the Taiwan habu snake, searching for genes that work alongside and interact strongly with the venom genes. They identified around 3,000 of these 'cooperating' genes, which protected the cells from stress caused by producing lots of proteins and were also key in regulating protein modification and folding. The long chains of amino acids which form proteins must fold in a specific way — if not, they can accumulate and damage cells.

"So to ensure you can manufacture all these proteins, you need a robust system in place to make sure the proteins are folded correctly so they can function effectively," said Barua. The team also looked at genomes of other creatures across the animal kingdom, like those of mammals such as dogs, chimpanzees and humans, and found that they contained their own versions of these genes.

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They also found, in the salivary glands of these species, that the genes had a similar pattern of activity to that which is seen in snake venom glands. This may mean that salivary glands in mammals and venom glands in snakes share an ancient functional core that remains since the split of the two lineages, around 310–320 million years ago during the Carboniferous period. Barua added that many scientists have "intuitively believed" this to be true, but that this was the first real, solid evidence.

He said that the apparent ease with which the function of salivary glands can be repurposed to be venomous is startling and could lead scientists to look at other mammals in a disconcerting new light. Barua spoke of experiments in the 1980s that showed the compounds of saliva in male mice being highly toxic when injected into rats. "If under certain ecological conditions, mice that produce more toxic proteins in their saliva have better reproductive success, then in a few thousand years, we might encounter venomous mice," he said.

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No superpowers, yet

Bryan Fry, a biochemist and venom expert at The University of Queensland in Australia who was not involved in the research, said it's going to be a real landmark in the field. "They've done an absolutely sensational job of some extraordinarily complex studies," he said. Humans, over the course of time, have invented tools, weapons and social structures that have ensured our survival without the need for venomous fangs like snakes. And venom, which needs to fold all the proteins, takes energy and is thus costly. For that reason, venom is easily lost when it isn't used.

Even so, an easy entry into Marvel's Serpent Society is sadly not on the cards, since the new study may not raise many hopes for new superpowers for humans. However, understanding the genetics behind the control of venom could be key for medicine, Fry said. Studying how genes control expression in different tissues may be helpful in our understanding of diseases such as cancer, which causes illness and death in large part because tissues start growing out of control and secreting products in places in the body where they shouldn't, Live Science reported.

The research was published online Monday (March 29) in the journal Proceedings of the National Academy of Sciences.
