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Comment by elliekelly | Hacker News Reader

> Although no known contemporary mammals display anti-predator eyespots, the effects of eye patterns and gaze have been shown to modify behaviour in this Class including in humans, domestic and wild canids, and domestic cats.

Is there a reason mammals don't/haven't evolved this way? With cattle and other domestic animals I can understand that humans have been knowingly and unknowingly interfering with evolution so I suppose that isn't surprising. But why haven't deer or bunnies, for example, evolved to have white patches on their rear ends the way insects and birds have?

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> But why haven't deer or bunnies, for example, evolved to have white patches on their rear ends

They have. Bunnies famously have distinct white tails that bob up and down as they run.

http://blogs.nature.com/news/2013/08/why-rabbits-have-white-...

And some deer have distinct white/dark patches on their backside:

https://krahnpix.files.wordpress.com/2012/09/t6c8813.jpg

https://i.imgur.com/6JZdQBz.jpg

The article conjectures that the function of these is to be a super-salient signal for a predator's visual system, so they attend to the wrong end of the prey in a chase. Maybe tracking the back end gives a degraded cue to the predators prey-motion-model. But the high-contrast patches are hard to ignore, like chaff for radar.

This is probably a different effect than false eyes have on cats, since cats sneak up on prey that aren't looking.

I'd guess possibly time? Insects have had a lot more generations filled with more frequent predation attempts and they've been doing it for longer. There is a lot more variation across insects than across mammals.

>Is there a reason mammals don't/haven't evolved this way?

Zebra is likely the closest adaptation. That's more of an optical illusion than eye logic.

I suspect it has to do with how fast big predators learn. If you put a fake snake in a fruit tree for example it takes about a month before the birds learn. Big apex predators learn even faster presumably. So that's just too fast on a evolution time scale.

Maybe there's not enough evolutionary pressure from predation to necessitate it. For deer and rabbits, they seem to be optimizing for speed and agility which makes other deterrence modes less necessary.

An eye pattern only deters ambush predators and the pattern could make them more vulnerable to other predators.

Sounds like the predators may eventually learn that they're fake:

"it is recommended that the technique be applied periodically, when predation rates are higher, also to avoid predator habituation."

With their bigger brains, perhaps cats and wolves can learn or visually identify discrepancies better than birds.

Fawns are covered in white spots, could that be why?

As for other animals, the RNG probably just didn't spin that way.

I suppose if they all had it, noone would be fooled anymore.

That argument would seem to apply to insects with eye markings as well, so can't be correct here.

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