Testosterone is a hormone that is produced in large amounts by males (and a little bit in females), in the testes and adrenal glands. High testosterone levels are associated with sexual performance, reproductive function, muscle mass, hair growth, aggressive, competitive behaviors, and other such manly things. Testosterone levels tend to peak at the age of 40, and slowly decline from there. Luckily, there are many things you can do to increase testosterone, so if you feel like your T levels could use a boost, you've come to the right place.
This, by the way, leads to a perilous tissue accumulation of estrogen. Researcher have discovered this in the prostate. [ 12 ] In fact, that same study concluded that "the prostatic accumulation of DHT, estradiol, and estrone is in part intimately correlated with aging". Estradiol and estrone are two forms of estrogen, neither of which do you want accumulating in your tissues. In other words, male menopause or andropause is as much about estrogen as it is about testosterone .
An animal defending against a predator may engage in either " fight or flight " in response to predator attack or threat of attack, depending on its estimate of the predator's strength relative to its own. Alternative defenses include a range of antipredator adaptations , including alarm signals . An example of an alarm signal is nerol, a chemical which is found in the mandibular glands of Trigona fulviventris individuals.  Release of nerol by T. fulviventris individuals in the nest has been shown to decrease the number of individuals leaving the nest by fifty percent, as well as increasing aggressive behaviors like biting.  Alarm signals like nerol can also act as attraction signals; in T. fulviventris, individuals that have been captured by a predator may release nerol to attract nestmates, who will proceed to attack or bite the predator.