Why do snakes produce poison? Not for self defense, research shows


Snake venoms vary greatly in species depending on their composition and effects, which is the main problem in the development of treatment methods. Snakes use these poisons to two main goals, The first is food prey, where the poison helps the snake to defeat its prey before eating it. The second is self-defense from potential predators – this is how millions of people bite and kill about 100,000, Every year,

Many studies have shown that the need to catch and eat prey often leads the evolution of various snake venoms. For example, many species have poisons that are especially deadly for their main prey, On the other hand, scientists know surprisingly little on the role of natural selection for self-defense in the evolution of poisons.

Western rattlesnakeCrotalus atroxin a defensive stance.
Wolfgang Wuster, The author provided

If a bee has ever stung you, you will know that the bite hurts almost immediately, and the pain quickly reaches its peak. And if you think a bee sting is not a big deal, think about the consequences. stinging lionfish, Here the intensity of the pain is much stronger, but its rapid onset is the same.

This has a biological meaning. The function of a protective poison is to deter and repel a predatory attack before its carrier is killed or injured, and pain is a universal deterrentIf the evolution of snake venom were caused by natural selection for protection, we would expect to see the same picture – an almost immediate pain strong enough to be a deterrent. But is it?

Sssself defense?

there is often severe snakebite painBut little was known about the timing of the development of pain. If the pain occurs long after the bite, it may just be a side effect of other properties of the poison, such as tissue damage.

The ideal organism to test this idea on is a species that is regularly exposed to poisonous snake bites from a wide variety of snakes and can accurately report the effects of a bite. This body model Homo sapiensIn particular, snake keepers, reptile researchers and environmentalists who work with them in the field.

Researcher at Bangor University Harry Ward-Smith to take advantage of the collective snakebite experience gained by this demographic group. developed and distributed a questionnaire asking them about past venomous snake bites and, in particular, how pain developed after being bitten.

Bites are common for snakes, but it seems that most snakes have not developed poison for self-defense.
mr.kie / Shutterstock

Respondents were asked to report their pain level on a scale of 0 to 10 one minute and five minutes and the maximum pain level at any time after a bite. The goal was to focus mainly on the timeline for the development of pain, and not on the pain levels themselves. The rationale was that, although the intensity of the pain experienced will vary greatly from person to person, the time for the onset of pain should be more consistent. Different people may consider a bee sting as minor inconvenience or unbearable, but everyone agrees that it hurts immediately.

The survey involved 368 people, who in total received 584 bites from 192 different types of snakes. Of course, the most common experience is associated with a relatively low level of pain after a bite during the first five minutes, when the pain can hold the predator in time so that the snake avoids injury or death.

More severe pain was often followed later. Less than fifteen% cases resulted in pain that subsided within five minutes after the bite, and approximately 55% of cases never reached this level. These results strongly suggest that self-defense does not stimulate the evolution of snake venom.

We also examined the presence of poisons that caused early-onset pain in the evolutionary tree of snake species. We found that poisons that cause early pain developed several times, but usually quickly disappeared again during the evolution of the snake. Again, this suggests that snakes do not have poison in response to the need to repel potential predators.

Some venomous snakes such as this Brazilian kaissaka (Obeshe Mukheni), have toxins with the main function of causing pain.
Wolfgang Wuster, The author provided

There are probably exceptions. For example, some coral snakes and Pit vipers have specific pain-causing toxins in their poisons. Cobra spitting is unique behavioral adaptations for the protective use of poison and their poisons cause severe pain in contact with eyes,

Those who feel a personal threat to the existence of dangerously poisonous snakes can be calm. In general, he is not aimed at us.



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