Why Does Testosterone Aromatase Into Estrogen

[Tarmander]

I was trying to come up with an evolutionary answer for this. It seems odd that this hormone that would give strength, muscle growth, and general anabolic/androgen like effects, would convert then into Estrogen. Does anyone have any kind of evolutionary explanation that would make aromatization a boon to survival and reproduction?

 

[tara]

How about, hypothetically: estrogen tends to lower metabolism. Under conditions of prolonged nutrient deficiency, reduced metabolism, reduced temperaure and reduced muscle mass may have survival value because this may allow the core functions to continue operating for longer withthe available resources.

Eg. Someone whose base metabolism requires 1500 kcal/day may survive longer than someone whose base metabolism requires 3000kcal, if only 1500kcal each is available over a prolonged period. Because the high metabolism will catabolise vital organs for energy before the low metabolism person (assuming similar starting fuel stores).
An ability to store fat efficiently when food is available would also have survival value in periods of intermittent famine.

Or someone who only has access to a lot of otherwise empty calories and very little B vitamins (or vit-A, or other vital micronutrients) may survive longer if their metabolism is slower.

Such conditions have probably arisen sufficiently to exert evolutionary pressure, and are still very common.