Early infancy androgen effects are the least understood. In the first weeks of life for male infants, testosterone levels rise. The levels remain in a pubertal range for a few months, but usually reach the barely detectable levels of childhood by 4–7 months of age. The function of this rise in humans is unknown. It has been theorized that brain masculinization is occurring since no significant changes have been identified in other parts of the body. The male brain is masculinized by the aromatization of testosterone into estrogen, which crosses the blood–brain barrier and enters the male brain, whereas female fetuses have α-fetoprotein, which binds the estrogen so that female brains are not affected.
Fatherhood decreases testosterone levels in men, suggesting that the emotions and behavior tied to decreased testosterone promote paternal care. In humans and other species that utilize allomaternal care, paternal investment in offspring is beneficial to said offspring's survival because it allows the parental dyad to raise multiple children simultaneously. This increases the reproductive fitness of the parents, because their offspring are more likely to survive and reproduce. Paternal care increases offspring survival due to increased access to higher quality food and reduced physical and immunological threats. This is particularly beneficial for humans since offspring are dependent on parents for extended periods of time and mothers have relatively short inter-birth intervals, While extent of paternal care varies between cultures, higher investment in direct child care has been seen to be correlated with lower average testosterone levels as well as temporary fluctuations. For instance, fluctuation in testosterone levels when a child is in distress has been found to be indicative of fathering styles. If a father's testosterone levels decrease in response to hearing their baby cry, it is an indication of empathizing with the baby. This is associated with increased nurturing behavior and better outcomes for the infant.
The other component of that study is that the subjects ate much less saturated fat. Saturated fats are common in meat, butter, and coconut products, and they’re crucial for your body to function. Saturated fats keep the integrity of your cell membranes, and if you limit carbs and/or do Bulletproof Intermittent Fasting, saturated fats become a phenomenal source of energy for your brain.
Exercise is the original testosterone booster, and it’s one of the most powerful full-body hacks around. Men see a sharp increase in both testosterone and human growth hormone (HGH) after lifting weights, and the boost is greater with shorter rest time between sets (1 minute rest outperforms 3 minutes rest) . With the shorter rest time, women also get a large boost in HGH.
In a recent study of male workers, men with low testosterone levels had an increased chance of severe erectile dysfunction (Kratzik et al 2005), although such a link had not been found previously (Rhoden et al 2002). Certainly erectile dysfunction is considered part of the clinical syndrome of hypogonadism, and questions regarding erectile dysfunction form part of the clinical assessment of patients with hypogonadism (Morley et al 2000; Moore et al 2004).