AA may have evolved to protect men from prostate cancer by increasing UV exposure

[sachalamp]

http://www.ncbi.nlm.nih.gov/pubmed/17910907

Androgenic alopecia affects populations adapted to colder climate, and individuals at an age and hormonal status susceptible to prostate cancer. Male pattern baldness enhances absorption of UV radiation on the top of the head, an area directly exposed to sunlight during everyday activities. Ultraviolet radiation is reported to reduce the risk of advanced prostate cancer. Here I propose that progression of androgenic alopecia rather than being a risk factor is a finely tuned mechanism evolved to protect against prostate cancer.

[...]

Another line of epidemiological studies suggest reduced risk of prostate cancer associated with sun exposure, outdoor activity, highly active vita- min D receptor variants [9], high level of vitamin D [10], childhood sunburn, regular foreign holidays, sunbathing score, high exposure to UVR [11] or liv- ing at lower latitude [12], results all pointing at the protective role of sun exposure.

For full text ask me on pm and i'll deliver it.

So there can be a link between vitamin D synthesis and DHT or other markers/hormones etc

Pair that with the fact that vitamin D synthesis needs cholesterol/fat to metabolize in skin, and there's an explanation for greasy scalp and hair loss. And consider that people are advised to wash hair frequently in case of hair loss which might worsen the symptoms since it strips the fats needed to make vitamin D.

The scalp is very vascularised which might explain the horseshoe pattern. http://www.erexam.org/wp-content/upl...asculature.png

Pair that with the fact that western society rarely gets any Sun, and vit D synthesis happens under UVB only (which has a narrow wavelength and which happens in a narrow timeframe, usually noon and in warm months when Sun is perpendicular to Earth - basically, the more inclined the angle it enters the atmosphere, the less UVB gets through), and that glass filters out UVB (so if you sit indoors behind a glass and Sun shines on you at noon, there will be 0 vitamin D synthesis).

I found this interesting for many reasons, particularly it's possible connection to p**rn/masturbation (overload on prostate, especially if its binging for 15+ minutes, which is a low estimate for p**rn masturbation; and because seeing multiple willing females increases secretion, so it's another overload).

Even more interesting considering Propecia was initially used as prostate treatment. (and Saw Palmetto as well)

 

[frenchy]

na it's just a mutation not subject to selection, cauz most ppl reproduce before going >nw3, so it doesn't affect once fitness.

and can't remember well about that part but it can also be transmited through mother's genom

 

[whatevr]

Balding probably has as much of an evolutionary purpose as prostate cancer.
It's solely negative. It doesn't convey any evolutionary advantage to the one who has it. None, nada, zilch. Maybe scientists should stop trying to create stupid hypotheses out of nothing, accept that it's a disease and try curing it?

 

[logikmtr]

na

I'm not sure why this hypothesis is so hard to believe. It's pretty clear that hair is an indicator of health; every little thing affects it. Hormones, stress, lack of sleep, illness, the wrong chemicals touching your skin (see "wen" shampoo), and yes, deficiencies of any kind.

Yeah, it's more likely a hormone/prostaglandin issue, but if any one of these other things are not addressed, then you aren't building on a solid foundation. This hypothesis at least makes a lot more sense than the "some men evolved to bald so that we would know who the masculine, tough 'leaders' are" hypothesis. Give me a break.

 

[InBeforeTheCure]

Balding probably has as much of an evolutionary purpose as prostate cancer.
It's solely negative. It doesn't convey any evolutionary advantage to the one who has it. None, nada, zilch.

I think baldness is probably more of a side effect rather than the target of selection. The risk genes for Androgenetic Alopecia are mostly transcription factors with wide biological functions.

 

[sachalamp]

>a hormone/prostaglandin issue

On top of that, it's the prostate that's acting like a gland to produce DHT.