The ability to ramp up testosterone production appears to drive male dark-eyed juncos to find and win mates, but it comes with an evolutionary cost. Big fluctuations in testosterone may also cause males to lose interest in parenting their own young, scientists have learned.

Novel research published in the current issue of The Journal of Sexual Medicine supports the claim that women with hypoactive sexual desire disorder or HSDD (persistent or recurrent deficiency and/or absence of sexual fanatasies/thoughts, and/or desire for, or receptivity to, sexual activity, which causes personal distress) show noted improvement in sexual desire and sexual function following low dose testosterone treatment.

For decades, older women have taken hormone replacements to replenish estrogen and progesterone levels lost to aging. More recently, testosterone (the most important male hormone) supplements have been used by aging men to improve their muscle mass, bone strength, libido and quality of life.

Everybody loses their hair. In some cases, alopecia or baldness occurs in a rather slow way; people get old yet still have some hair to be done by a hairdresser on a regular basis. Others start going bald or having thinning hair in their early twenties. What are the causes of alopecia?

Human sperm cells travel up to 6 meters in their transit from testes to penis, and most of that journey occurs in the epididymis, a tightly coiled tube that primes the cells for their ultimate task: fertilization. In a paper released this week in the Proceedings of the National Academy of Sciences, researchers at the University of Illinois report that they have discovered a gene – and related mechanism – essential to the embryonic development of the epididymis.

Close on the heels of a large-scale clinical trial just underway to confirm that the female hormone estriol combats the effects of multiple sclerosis (MS) in women, a just completed pilot study at UCLA now shows promise for the use of testosterone to combat its effects in men.