Highly venomous Cape cobra, Naja nivea, in threat posture
Source: Times Newspapers
Photo: Willem van Zyl
Photo: Willem van Zyl
A team of researchers from Queensland University, Australia, and Oxford Brookes University, Oxford, UK, led by Associate Professor Bryan Fry, has discovered evidence of an evolutionary arms race between Afro-Asian primates and venomous snakes, especially the cobras, which has given us an increased resistance to the neurotoxin in cobra venom, compared to other mammals and the primates of Madagascar where there are no venomous snakes and South America where venomous snakes are usually small, nocturnal and burrowing.
In doing so, they have also produced yet more evidence of the evolutionary relationship between the other African apes and Homo sapiens, who together form the Hominidae clade, sharing a common ancestor in which this resistance is thought to have evolved. In members of this clade, the resistance is especially marked, though not complete since cobra venom can still kill us.
As primates from Africa gained the ability to walk upright and dispersed throughout Asia, they developed weapons to defend themselves against venomous snakes, this likely sparked an evolutionary arms race and evolving this venom resistance.
This was just one of many evolutionary defences – many primate groups appear to also have developed excellent eyesight, which is thought to have aided them in detecting and defending themselves against venomous snakes.
But Madagascan Lemurs and Central and South American monkeys, which live in regions that haven’t been colonised by or come in close contact with neurotoxic venomous snakes, didn’t evolve this kind of resistance to snake venoms and have poorer eyesight.
It’s been long-theorised that snakes have strongly influenced primate evolution, but we now have additional biological evidence to support this theory.
This was just one of many evolutionary defences – many primate groups appear to also have developed excellent eyesight, which is thought to have aided them in detecting and defending themselves against venomous snakes.
But Madagascan Lemurs and Central and South American monkeys, which live in regions that haven’t been colonised by or come in close contact with neurotoxic venomous snakes, didn’t evolve this kind of resistance to snake venoms and have poorer eyesight.
It’s been long-theorised that snakes have strongly influenced primate evolution, but we now have additional biological evidence to support this theory.
Richard Harris, lead-author
PhD candidate
Venom Evolution Lab
University of Queensland
Biological Sciences, St. Lucia, Brisbane, Australia
PhD candidate
Venom Evolution Lab
University of Queensland
Biological Sciences, St. Lucia, Brisbane, Australia
Our movement down from the trees and more commonly on land meant more interactions with venomous snakes, thus driving the evolutionary selection of this increased resistance.
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.
We have shown in other studies that resistance to snake venoms comes with what’s known as a fitness disadvantage, whereby the receptors don’t do their normal function as efficiently, so there is a fine balance to be struck where the gain has to outweigh the loss.
In this case, partial resistance was enough to gain the evolutionary advantage, but without the fitness disadvantage being too taxing.
We are increasingly recognising the importance snakes have played in the evolution of primates, including the way our brain is structured, aspects of language and even tool use.
This work reveals yet another piece in the puzzle of this complex arms race between snakes and primates.
According the Queensland University News: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.
We have shown in other studies that resistance to snake venoms comes with what’s known as a fitness disadvantage, whereby the receptors don’t do their normal function as efficiently, so there is a fine balance to be struck where the gain has to outweigh the loss.
In this case, partial resistance was enough to gain the evolutionary advantage, but without the fitness disadvantage being too taxing.
We are increasingly recognising the importance snakes have played in the evolution of primates, including the way our brain is structured, aspects of language and even tool use.
This work reveals yet another piece in the puzzle of this complex arms race between snakes and primates.
Associate Professor, Dr. Bryan Fry, team leader and supervising author
Venom Evolution Lab
University of Queensland
Biological Sciences, St. Lucia, Brisbane, Australia
Venom Evolution Lab
University of Queensland
Biological Sciences, St. Lucia, Brisbane, Australia
The team studied various snake toxin interactions with synthetic nerve receptors, comparing those of primates from Africa and Asia with those from Madagascar – which doesn’t have venomous snakes – and those from the Americas – where the cobra-related coral snakes are small, nocturnal and burrowing. Team leader Associate Professor Bryan Fry said the study also revealed that in the last common ancestor of chimpanzees, gorillas, and humans, this resistance was sharply increased.One of the problems to be overcome as a species evolves resistance to a neurotoxic venom, stems from the way these venoms work. In the case of cobra venom it contains α-neurotoxins which target nicotinic acetylcholine receptors, binding to them, so blocking these essential metabolic pathways. Any changes which modify these receptors, so making the α-neurotoxins less effective, will also reduce the efficiency of the pathway of which these receptors are a part, so there is an inevitable evolutionary trade-off between this cost and any benefits from increased resistance.
A similar phenomenon is involved in the evolutionary arms race between Garter snakes and rough-skinned newts, only in this case it is a snake evolving resistance to a toxin produced by a potential prey species. I used this as an example of any creator of this system indulging stupidly in an arms race with itself, in my book, The Unintelligent Designer: Refuting the Intelligent Design Hoax.
We see this same stupidity in the arms race between the primates and cobras, reaching its peak in the Hominidae.
The teams report is published open access in BMC Biology:
AbstractIt is facts like this that expose Intelligent [sic] Design as a hoax aimed at scientifically illiterate fools who will remain wilfully ignorant of the very many arms races in nature which are one of the main drivers in evolution. Nothing that could conceivably be described as intelligent would indulge in a competitive arms race with itself and nothing that could be described as omni-benevolent would create the predator-prey and parasite-host relationships which give rise to these arms races in the first place.
Background
Snakes and primates have a multi-layered coevolutionary history as predators, prey, and competitors with each other. Previous work has explored the Snake Detection Theory (SDT), which focuses on the role of snakes as predators of primates and argues that snakes have exerted a selection pressure for the origin of primates’ visual systems, a trait that sets primates apart from other mammals. However, primates also attack and kill snakes and so snakes must simultaneously avoid primates. This factor has been recently highlighted in regard to the movement of hominins into new geographic ranges potentially exerting a selection pressure leading to the evolution of spitting in cobras on three independent occasions.
Results
Here, we provide further evidence of coevolution between primates and snakes, whereby through frequent encounters and reciprocal antagonism with large, diurnally active neurotoxic elapid snakes, Afro-Asian primates have evolved an increased resistance to α-neurotoxins, which are toxins that target the nicotinic acetylcholine receptors. In contrast, such resistance is not found in Lemuriformes in Madagascar, where venomous snakes are absent, or in Platyrrhini in the Americas, where encounters with neurotoxic elapids are unlikely since they are relatively small, fossorial, and nocturnal. Within the Afro-Asian primates, the increased resistance toward the neurotoxins was significantly amplified in the last common ancestor of chimpanzees, gorillas, and humans (clade Homininae). Comparative testing of venoms from Afro-Asian and American elapid snakes revealed an increase in α-neurotoxin resistance across Afro-Asian primates, which was likely selected against cobra venoms. Through structure-activity studies using native and mutant mimotopes of the α-1 nAChR receptor orthosteric site (loop C), we identified the specific amino acids responsible for conferring this increased level of resistance in hominine primates to the α-neurotoxins in cobra venom.
Conclusion
We have discovered a pattern of primate susceptibility toward α-neurotoxins that supports the theory of a reciprocal coevolutionary arms-race between venomous snakes and primates.
Harris, R.J., Nekaris, K.AI. & Fry, B.G.
Monkeying around with venom: an increased resistance to α-neurotoxins supports an evolutionary arms race between Afro-Asian primates and sympatric cobras.
BMC Biol 19, 253 (2021). DOI: 10.1186/s12915-021-01195-x
Copyright: © 2021 The authors. Published by Springer Nature
Open access
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
On the other hand, evolutionary arms races are the inevitable, and entirely predictable, result of mindless, unplanned, evolution by natural selection.
great post - tx for sharing
ReplyDeleteCobras are horrible animals. Venomous snakes such as Cobras, Mambas, Puff Adders, Taipans, Rattlesnakes, Water Mocassins, Kraits, Russell's Vipers, the Fer Dr lance, etc, all cause serious pain and sickness from their bites. Cobras and Vipers kill thousands of people a year.
ReplyDeleteVenomous spiders such as Widow spiders, Recluse spiders, the Sydney funnel web spider, the Brazilian wandering spiders have seriously painful venoms. Some tropical Tarantulas such as the Orange baboon Tarantula from Africa are very bad tempered and the venom is said to be more painful than childbirth.
The male Duckbill Platypus also has an agonizingly painful venom which is beyond imagining. It's a venomous mammal. Yes there are such things. The venom is so torturously painful and can last 3 months. One victim was said to have committed suicide from the pain.
Bullet ants, Giant water bugs, the Death Stalker Scorpion, the Gila monster(a venomous lizard), Sting rays, the Cone Snail, Weever fish, and the Stonefish all have unbelievably painful venoms which can make a victim scream, thrash, and writhe in agony. The Box jellyfish might be the worst of all as its venom is so brutally painful it can cause its victims to scream and thrash in agony and has even been known to cause a victim to lose consciousness. The body cannot handle such horrific, violent pain. What kind of cruel, sadistic, malevolent demon creates such horrible animals? Whoever or whatever created these horrible things must have been fond of cruelty, pain, torture, and killing. It's demonic, devilish, and Satanic. The creator of these horrors is a cruel, sadistic, malevolent bastard. Evil.