From Eurekalert:
Stripes might not offer protection for animals living in groups, such as zebra, as previously thought, according to research published in Frontiers in Zoology. Humans playing a computer game captured striped targets more easily than uniform grey targets when multiple targets were present. This rebukes assumptions that stripes evolved to make it difficult to capture animals moving in a group.
Rebukes? Hey, guys, this is St. Darwin of Sandwalk we are talking about!
Anna Hughes, University of Cambridge, says “We found that when targets are presented individually, horizontally striped targets are more easily captured than targets with vertical or diagonal stripes. Surprisingly, we also found no benefit of stripes when multiple targets were presented at once, despite the prediction that stripes should be particularly effective in a group scenario. This could be due to how different stripe orientations interact with motion perception, where an incorrect reading of a target’s speed helps the predator to catch its prey.”
Stripes, zigzags and high contrast markings make animals highly conspicuous, which you might think would make them more visible to a predator. Researchers have wondered if movement is important in explaining why these patterns have evolved. Striking patterns may confuse predators and reduce the chance of attack or capture. In a concept termed ‘motion dazzle’, where high contrast patterns cause predators to misperceive the speed and direction of the moving animal. It was suggested that motion dazzle might be strongest in groups, such as a herd of zebra.’ More.
But how did they find this out? Not from lions, it seems. “A total of 60 human participants played a game to test whether stripes influenced their perception of moving targets .” In short, they did all their research on humans, and natural predators of zebras were not consulted.
They could be right, but for now, file under: Next time, go to the source.
This is one of the disadvantages of the “Humans are just like other animals” thesis. The thesis makes it easy to miss the obvious point that the human may be approaching the task in quite a different way and with different concerns from those of a hungry pride of lionesses with cubs to feed.
See also: Talk to the fossils: Let’s see what they say back. Evolution is not what we have thought.
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