Can evolution explain why humans/animals get sunburns?

Question

It would seem to me that evolution would do away with sunburns. After millions of years it would seem we would be better able to defend ourselves againist this.

Answer 1

Evolution can’t explain sunburn, but biochemistry can. UV light has sufficient energy to cause chemical reactions on exposed skin. With sufficient exposure, enough damage accumulates to cause a burn. What evolution can explain are some of the adaptations to UV light that have developed.

Your question shows one of the common ways people misunderstand evolution. Evolution is not a process of perfection. It is not directed. It cannot plan for the future. There is no such thing as devolution. Random variations in a population are selected for and those that are best able to adapt and survive under a set of environmental conditions are more likely to propagate and pass on those traits. Change those conditions and what was an advantage can become a liability. For example, why are there bacteria that are still susceptible to antibiotics? Why don’t they all become superbugs that are resistant to all known antibiotics? Because, it takes energy and resources to make all those defensive mechanisms to be antibiotic resistant. That’s fine when there are antibiotics around but in the absences of antibiotics, these supergerms have to compete with cells that don’t have to spend resources for a defense against a nonexistent threat.

UV exposure has been a threat for a long time so animals, including humans, have developed traits that defend against UV light. The obvious one is pigments in skin, which was sufficient until supposedly intelligent apes thought it was aesthetically appealing to acquire precancerous coloration and intentionally bask in sunlight. Another defense that is shared by almost all animals is a period of programmed dormancy in the middle of the day. Even fruit flies have a built in program for a siesta so that they are not active while sunlight is most intense.

Answer 2

Sun burn is a sign from your skin that if you stay longer in the sun you are going to get fried/skin damage, and you better go and sit in some nice shade. For a lot of people it obviously takes pain to get the message across. Pain is the evolutionary valuable signal of the body that something is wrong and tells you to stop doing the harmful thing which is causing it.

Being black from birth is the body's protection from sun burn. Getting a tan is the bodies reaction for white people to protect it. I expect that there is some energetic expense in producing melatonin, so you are better off if you don't produce it if you don't need to (e.g. you live in Iceland and don't see much sun for the next 6 months), that's why not everybody is black, because the caucasian people lost that nice pigmentation due to living in a cold and dark climate for a good part of the year.

Evolution already dealt with your sunburn by allowing you to tan, though it hasn't had time to develop the superfast tan which allows you to spend all winter and spring in front of your computer/TV and then suddenly come out for summer vacation. That kind of behavior patter is extremely recent, so sorry, your body is not optimized for that kind of behavior.

I don't know of any non-domestic animals which get sunburn? Which ones do?

Answer 3

In the short-term, sunburns are more of an irritant rather than life-threatening. Skin cancer doesn't happen for many years, and by the time it happens, most organisms have already succeeded in reproducing. Things that kill you slowly (and still allow an organism to reproduce) are not selected out as rapidly as things that kill an organism right away.

Through evolution, organisms have in fact developed a number of effective counters to sunburn. The most important is probably the brain and nervous system: organisms can feel pain where they've received a nervous system, and can then attempt to protect the damaged area from further harm. Humans in particular have evolved problem-solving brains that are capable of recognizing the causes of sunburns, and can then take measures to prevent receiving them. Skin pigmentation (in humans) and coverings (such as fur on other animals) can also provide protection from the sun.

Answer 4

No we are in an evolutionary trap. We need the sun as Vitamin D is produced under the skin when the sun is shining on it. Some Muslim women can develop bone defects in their skeleton hiding behind their cover if they are living up north, but they can compensate it with milk. The white man might be a mutation of the black people, if one look upon some medical defects., but even a deep colored person can be burned in the sunlight. The sunlight makes your skin thicker to protect you, but be careful not to burn your self as at the same time you can destroy the perspiration glands on your body. Have a nice suntan.

Answer 5

Yes. I think you are really intelligent and magnificient. The evolution of humans seem to point in some direction that is living in a cave or shelter. However for animals, maybe it is the reason that they are not in the sun. Like maybe it is the jungle shades. But however like the birds can fly, the skin is sensitive so he can feel it.

Answer 6

sun burns are only a recent problem because of the weakening of the ozone layer

if the ozone layer was as thin as it was a long time ago, people would most likely have developed some stronger natural defense to UV rays

darker people do burn, but they have a higher tolerance

Answer 7

for races that come from areas with a lot of sun exposure they do have darker skin so they dont burn as bad. the lighter skinned peoples come from areas where they dont have to worry about it.

Answer 8

Well, it almost has. If you're black, you burn less readily. Of course, staying in the shade is good, too.