Evolution Intelligent Design

A hair-raising theory for why zebras have stripes

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Grant’s zebras/© salparadis / Adobe Stock

You’d think we’d know by now but… From ScienceDaily:

The data revealed a temperature difference between the black and white stripes that increases as the day heats up. Whilst this difference stabilises on living zebras during the middle seven hours of the day, with the black stripes 12-15ºC hotter than the white, the stripes on a lifeless zebra hide continue to heat up, by as much as another 16ºC. This indicates there is an underlying mechanism to suppress heating in living zebras. It is therefore the way the zebra stripes are harnessed as one part of their cooling system, rather than just their contrasting coat colour, that is key to understanding why these animals have their unique patterning. …

The researchers propose that the differential temperatures and air activity on the black and white stripes set up small-scale convective air movements within and just above the stripes, which destabilise the air and the water vapour at the tips of the hairs.

During the field research, the authors also observed — probably for the first time — that zebras have an unexpected ability to raise the hair on their black stripes (like velvet) while the white ones remain flat. The authors propose that the raising of black hairs during the heat of the day, when the stripes are at different temperatures, assists with the transfer of heat from the skin to the hair surface and conversely, when the stripes are at the same temperature in the early morning, and there is no air movement, the raised black hairs will help trap air to reduce heat loss at that time. Paper. (open access) – Alison Cobb, Stephen Cobb. Do zebra stripes influence thermoregulation? Journal of Natural History, 2019; 53 (13-14): 863 DOI: 10.1080/00222933.2019.1607600 More.

Interesting. They’re onto something with the hair standing on end. But here are some of the other theories:

The Real Reason Why Zebras Have Stripes: To Shoo Away Flies

Stripes Confuse People But They Do Not Cool Zebras

Study: Zebra stripes neither hide nor flaunt

Stripes offer no advantage to zebra?

How the zebra got its stripes, this time really

How the zebra got its stripes, maybe

How the zebra did NOT get its stripes?

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3 Replies to “A hair-raising theory for why zebras have stripes

  1. 1
    EDTA says:

    > the stripes on a lifeless zebra hide continue to heat up, by as much as another 16ºC.

    Perhaps the blood circulation beneath the hide of a living zebra distributes heat, whereas on a dead zebra, there is no circulation to dissipate heat?

    (No matter what they do, I’ll bet plain old horses are stinking jealous of them.)

  2. 2
    vmahuna says:

    If there were ANY significant advantage to stripes, more of the grazing animals would have stripes.
    But if you watch ANY of the TV shows (Big Cat Diary is the best) that show footage of ACTUAL herds grazing their way up and down the savanna, you will see fancy “camouflage” patterns right next to crowds of dull tan. And of course the wildebeests go with all-over basic black, which means they should be dreadfully overheated and that they stand out against the faded tans of the plants.
    But, hey, if you want FUNDING for another worthless study, yer gonna havta propose some wacky NEW idea. My only complaint is that we (Humanity) are NOT getting any new KNOWLEDGE from this nonsense.

  3. 3
    SmartAZ says:

    When you ask “Why,” you are introducing Lamarckism. Evolutionists reject Lamarckism, but when they want to explain something, that is exactly what they use to make it sound reasonable.

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