tuisto at oz.net writes:
>
> In addition, as you
>>mentioned, birds have carotenoids that they get from their diets and

>modify

>into their feathers. Do mammals have that?
>
>No. Mammals have carotene in their fat (yellow fat, brown fat), but it
>doesn't contribute to skin or hair color. Note the general blandness of
>mammal colors as a consequence: blacks, grays, browns, dull yellows,
>near-reds and whites are about it.

Actually, there is one instance of carotene contributing to skin color, in
a way. Some years ago (over)consumption of orange juice became very
popular, especially in Southern California. As a result, B-carotene
could not be metabolised rapidly enough and the excess was deposited in
the subcutaneous fat leading to a very lively orange color to the skin.
>

>I guess I'm pretty skeptical about losing color to injuries. I will grant
>you that scar tissue is less pigmented (non-pigmented?), but if injuries
>caused pigment loss to any appreciable degree, we ought to all remember
>seeing (or being) people with big white patches in their skin.
<snip>
>I think I've seen

>a few people with blotchy skin, but I don't think it was because of

>injuries. The injury seems like it would have to selectively kill off the

>pigment cells or cause them to dedifferentiate while leaving the other

>epidermal cells intact. It seems implausible in most situations.

I can speak from experience that some types of injuries cause
depigmentation. I received a 2nd degree (blistering) sunburn on my arm
while mountain climbing, having missed an area with sunscreen.
Subsequently that area became depigmented and will no longer tan. I
assume that the melanophores were killed or deactivated.

This topic may seem off inappropriate for the list, but I don't thnk so.
It, like other related topics, help us understand the natural world in
general and birds in particular.

-------Herb Curl
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