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"When you notice a characteristic of an animal and ask what its Darwinian survival value is, you may be asking the wrong question. It could be that the characteristic you have picked out is not the one that matters. It may have "come along for the ride", dragged along in evolution by some other characteristic to which it is pleiotropically linked."
Usually, affected men show no symptoms, although they may have smaller testes. Men with this condition may exhibit azoospermia (no sperm production), oligozoospermia (small number of sperm production), or they may produce abnormally shaped sperm (teratozoospermia). [22] This case of infertility occurs during the development of gametes in the male.
Successful reproduction typically involves sexual intercourse between a healthy, sexually mature and fertile male and female. [1] During sexual intercourse, sperm cells are ejaculated into the vagina through the penis, resulting in fertilization of an ovum to form a zygote. [1]
In lighter-complected humans, male skin is visibly redder; this is due to greater blood volume rather than melanin. [48] [49] Conversely, females are lighter-skinned than males in some studied human populations. [50] [51] The differences in color are mainly caused by higher levels of melanin in the skin, hair and eyes in males. [52] [53]
A fertility MOT provides patients with an assessment of their fertility and reproductive health for a few hundred pounds, but some experts have raised concerns about the effectiveness of the tests.
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Measuring the anogenital distance in neonatal humans has been suggested as a noninvasive method to determine male feminisation and female virilization and thereby predict neonatal and adult reproductive disorders. [7] A study by Swan et al. determined that the AGD is linked to fertility in males, and penis size. [3]
Androgenetic alopecia, or male pattern baldness, is a common form of hair loss that can occur in your 20s, 30s, 40s or later in your life Over time, this hair loss may cause your frontal hairline ...