Spike Jones wrote:
> Wow! Thats a new one on me. Testosterone is essential? Do women
> need it too then? Why would it be essential for a man's health and not
> for a woman's? Elizabeth are you a doctor? Are testacles the only source
> of natural testosterone? Thanks in advance. spike
Yes, women need testosterone too. One third of it comes from the ovaries, and I'm not sure where the rest of it comes from, probably broken down from other hormones. In women, it regulates mood, energy, libido, bone density and muscle mass, and I believe it does the same in men. Women's testosterone levels tend to be about 10% of men's, however. Men have estrogen and progesterone, as well, and some doctors believe that imbalances in these hormones can dramatically effect men's health.
Hormones have all kinds of subtle effects on human behavior, which are altered when we take birth control pills or other types of artificial hormones. For example, a study was done where sweat was collected from men, then the different samples of sweat were presented to women. The women were asked which sweat smelled the best to them. They would consistently pick the sweat from the man whose immunities were the most complementary to their own. BUT, women on birth control pills would pick the man whose immunities were most similar to her own. The theory is that birth control pills simulate pregnancy, and during pregnancy a woman is evolved to want to be in the company of her relatives, who would have similar immunities.
(Whenever a girlfriend can't figure out why she got involved with a particular man, I always tell them about this study. It's the immunities.)
Women prefer more masculine male faces while they are fertile, but more feminine male faces while they are not fertile: http://news.bbc.co.uk/hi/english/sci/tech/newsid_376000/376321.stm
It's things like this that always make me wonder how people could ever develop a romance over the internet. There's a lot of biochemical information about a mate that you can't get remotely.
The extropian point would be that biochemistry is so darn complicated, particularly anything that involves the many interrelated hormones, that every time we try to change it we will run both foreseeable and unforseeable complications. If we had nanotech to do this, I would suggest disabling the mechanisms of action that causes the testosterone to increase the libido, rather than lowering the testosterone level. This might have fewer complications.
I am not a doctor, but here is a passage from a doctor that covers testosterone in women in more depth. This is from a book by Dr. Elizabeth Vliet, called "Screaming to Be Heard: Hormonal Connections Women Suspect, and Doctors Ignore." I believe this information is reliable, although she doesn't cite specific studies in this book, which is written for a general audience.
"Testosterone is one of a group of hormones called "ANDROGENS" which are made from cholesterol by the female ovary and adrenal glands. Androgens are also made from precursor "building blocks" in body fat tissue, muscle, and other sites. The word androgen is derived from the Greek andros meaning "male-like" and refers to any steroid molecule with 19 carbon atoms that is able to bind to the androgen hormone receptor sites in the brain and body. The amount of circulating active androgens in women is obviously much lower than in men, but these compounds are important for many normal functions in the female body.
Over the course of a woman's life, the ovary makes on average about one-third of a woman's circulating androgens, in addition to producing the female hormones estrogen and progesterone... There are potentially significant effects from the loss of testosterone: loss of sex drive, fatigue, declining muscle mass, decreased bone density, and changes in feelings of well being to name a few...
Testosterone has important functions in maintaining muscle tissues in women... and helping to build bone. Maintaining bone density is one of the crucial roles of testosterone for women, particularly as women grow older and lose the effects of estrogen in maintaining bone density. Furthermore, testosterone plays a key role in keeping a woman's energy level optimal. Decline or loss of this critical hormone is one of the frequently unrecognized factors in the mid-life problem of "chronic fatigue"... our psychological sense of well-being is also enhanced by testosterone. In some women, what appeared to be a depression turned out to be a deficiency of testosterone.
Too little testosterone:
Loss of sex drive
Mildly depressed mood
Thin, fine hair
Dry, thin skin
Too much testosterone:
A large excess of testosterone, in the amounts used by some bodybuilders, can cause violent and risky behavior.