Toxic showdown: ancient primates vs venomous snakes
An ancient primate ancestor evolved resistance to snake venom – and passed it down to us!
Venomous cobras may not seem like snakes we should get up close and personal with, but an ancient Homininae ancestor of chimps, gorillas and humans evolved strong resistance to neurotoxins in snake venom – and passed it on to us.
But grandad Homininae didn’t end up with resistance due to happenstance – it was part of an ongoing evolutionary arms race between African apes and deadly venomous snakes.
Over 10 million years ago – well before chimps and gorillas diverged but after orangutans did – grandad Homininae and friends were learning the lay of the land after coming down from the trees. He was picking up rocks, wandering around in shrubs, and waggling sticks. The problem was that these were also places frequented by venomous snakes, which could easily lead to a toxic bite or two.
And these neurotoxins are nasty.
“You can think of a particular type of neurotoxin like a heroin overdose,” says study author Bryan Fry, molecular biologist at the University of Queensland. “You die of flaccid paralysis, because the diaphragm, the muscle that moves your lungs, doesn’t move anymore.
“So, no movement of your lungs, no air. No air, no oxygen. No oxygen, no life.”
According to the study, published in BMC Biology, the threat of venomous snakes appeared to be a driving force towards developing resistance to neurotoxins – after all, a Homininae that’s remained alive after a snake bite is far more likely to pass on their genes than one that’s dead.
“Our movement down from the trees to walk more commonly on land meant more interactions with venomous snakes, thus driving the evolutionary selection of this increased resistance,” says Fry.
“It is important to note that this resistance is not absolute
– we are not immune to cobra venom, just much less likely to die than other primates.”
Interestingly, this resistance is still passed down to us today, meaning that we have proportionately 80% resistance – that’s around five times more resistance than lots of other primates who didn’t benefit from grandad Homininae’s good genes.
Thanks grandad.