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During puberty, a male's erect penis becomes capable of ejaculating semen and impregnating a female. [26] [27] A male's first ejaculation is an important milestone in his development. [28] On average, a male's first ejaculation occurs at age 13. [29] Ejaculation sometimes occurs during sleep; this phenomenon is known as a nocturnal emission. [25]
Among researchers who study puberty, the Tanner scale is commonly considered the "gold standard" for assessing pubertal status when it is conducted by a trained medical examiner. [5] In HIV treatment, the Tanner scale is used to determine which regimen to follow for pediatric or adolescent patients on antiretroviral therapy (adult, adolescent ...
Dihydrotestosterone, also known as (DHT) will differentiate the remaining male characteristics of the external genitalia. [11] Further sex differentiation of the external genitalia occurs at puberty, when androgen levels again become disparate. Male levels of testosterone directly induce growth of the penis, and indirectly (via DHT) the prostate.
The "extreme male brain" or empathizing–systemizing theory views the autism spectrum as an extreme version of male-female differences regarding systemizing and empathizing abilities. [113] It's used to explain the possible reason why males with ASD score higher on systemizing tests than females with ASD. [114]
Skeletons of female (left) and Male (right) black-casqued hornbills (Ceratogymna atrata). The difference between the sexes is apparent in the casque on the top of their bill. This pair is on display at the Museum of Osteology. Sexual dimorphism may also influence differences in parental investment during times of food scarcity.
One 2013 study found that women with metal hip replacements were 29% more likely than men to experience implant failure, possibly due to anatomical differences and inadequate testing in women.
The human brain. Differences in male and female brain size are relative to body size. [83] Early research into the differences between male and female brains showed that male brains are, on average, larger than female brains. This research was frequently cited to support the assertion that women are less intelligent than men.
Structurally, adult male brains are on average 11–12% heavier and 10% bigger than female brains. [21] Though statistically there are sex differences in white matter and gray matter percentage, this ratio is directly related to brain size, and some [ 22 ] argue these sex differences in gray and white matter percentage are caused by the average ...