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Humans ‘hard-wired to spot snakes’

snakePUNCHSTOCK.JPGHumans have an innate ability to spot snakes, according to University of Virginia researcher Vanessa LoBue.

She asked both adults and children to find a target picture from a set of nine images, these targets were either snakes, flowers, frogs or caterpillars. Both young and old detected the snakes faster than the other three (research abstract).

Snakes … why did it have to be snakes? Here’s why: “Our finding matches with the evolutionary theory that humans have a pre-disposition to quickly identify a snake. Throughout the course of human evolution, humans who could quickly visually detect the presence of snakes were able to survive and reproduce, thereby passing this capability on in the gene pool,” says LoBue (Feb 29th press release; hat tip yesterday’s LiveScience story).

She believes that the three-year olds used in this research wouldn’t have had much negative experiences of snakes and says those with no fear of snakes were just as quick to identify them. This might suggest an inate ability but I’m not entirely convinced it can’t just be explained by exposure to negative portrayals of snakes (the Jungle Book movie anyone?).

More snakes

Man wins right to keep 50 snakes in his house (WESH)

Cold snakes fall out of trees (Nature)

Image: Punchstock

Comments

  1. Report this comment

    T. Michael Keesey said:

    Throughout the course of human evolution, humans who could quickly visually detect the presence of snakes were able to survive and reproduce, thereby passing this capability on in the gene pool.

    Wouldn’t this more likely be an ancestral primate trait (or even older), rather than just a human trait?

    Very interesting, anyway.

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    Steven Ericsson-Zenith said:

    A number of questions immediately come to mind after reading this paper. But the most powerful questions really have to do, first with the genetic background of the participants of the study – their ethic heritage and the proximity of their ancestors to life threatening snakes (or perhaps there is some argument that this is a very early innate knowledge affecting the entire species), and second there is the question of the actual selective pressure of lethal snakes. How valid is the assumption that snakes posed such a threaten in real terms, and what exposure did the ancestors of the test subjects actually have to the supposed threat?

    For the conclusions of this study to be valid there would have to be some confirmation that snakes posed a real and common lethal threat to our ancestors; sufficient for natural selection to enforce such a bias.

    It would be instructive to see the result of a similar study that includes lethal flowers.

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    William Brookfield said:

    This would have been a much more interesting study if images of spiders had been included.

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    Ruth Rosin said:

    From the point of view of Schneirla’s School in Behavior, humans’ early-response to a fast slithering snake is just what the School dubs “a withdrawal” response, very common in many different organisms to stimuli of any modality,(visual, auditory, tactile, etc.), that undergo a fast increase in intensity; totally irrespective of whether the stimuli are associated with any real danger, or not.

    A human baby can thus, exhibit this “withdrawl” response, and start crying of a window being suddenly forced shut by the wind, even though this involves no danger at all.

    “Approach-withdrawl” responses usually gradually disappear in humans, as they grow older. But the “startle”-response is apparently still retained, perhaps for life, as any kid who ever enjoyed quietly sneaking behind a friend, and suddenly uttering a very loud scream, knows perfectly well.

    In short, you cannot expect to determine how a response to a picture of a snake developed in humans, by starting to investigate 3-year old kids, without knowing anything about their whole previous experience.

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    John Kuhlman said:

    What I find interesting, as a returning biology student, is how these traits are passed along from generation to generation. This almost makes LaMarck’s theories plausible: An event that impacts me is somehow encoded on my genes and is then passed along to my children.

    For example, if I develop a fear of baby bunnies, then that fear is genetically passed on to my future generations.

    I’m sure other people have looked into this. I just haven’t come across their theories yet.

    Nonetheless, it’s fascinating stuff.

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