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The hormonal theory of sexuality holds that, just as exposure to certain hormones plays a role in fetal sex differentiation, such exposure also influences the sexual orientation that emerges later in the adult. Differences in brain structure that come about from chemical messengers and genes interacting on developing brain cells are believed to ...
In life history theory, the cost of reproduction hypothesis is the idea that reproduction is costly in terms of future survival and reproduction. This is mediated by various mechanisms, with the two most prominent being hormonal regulation and differential allocation of internal resources.
This hypothesis is an extension of the theory of kin selection, which was originally developed to explain apparent altruistic acts which seemed to be maladaptive. The initial concept was suggested by J. B. S. Haldane in 1932 and later elaborated by many others including John Maynard Smith, W. D. Hamilton, Mary Jane West-Eberhard, and E. O. Wilson.
In fish, growth rates can be different between sexes. These differences can affect their economic value. Producing a monosex fish population can improve product quality and therefore generates higher financial profit. [14] Hormone-induced sex reversal is the most frequent method used in aquaculture.
The change at puberty is triggered by growth hormone, and its pulsatility differs in boys and girls. [clarification needed] In the third trimester of pregnancy, the SHBG level of the parent escalates to five to ten times the usual level for a woman. [7] [9] A hypothesis is that this protects against the effect of hormone produced by the fetus. [7]
In order to be active, steroid hormones must free themselves from their blood-solubilizing proteins and either bind to extracellular receptors, or passively cross the cell membrane and bind to nuclear receptors. This idea is known as the free hormone hypothesis. This idea is shown in Figure 1 to the right.
Sex hormones, also known as sex steroids, gonadocorticoids and gonadal steroids, are steroid hormones that interact with vertebrate steroid hormone receptors. [1] The sex hormones include the androgens , estrogens , and progestogens .
The fetal origins hypothesis (differentiated from the Developmental Origins of Health and Disease hypothesis, which emphasizes environmental conditions both before and immediately after birth) proposes that the period of gestation has significant impacts on the developmental health and wellbeing outcomes for an individual ranging from infancy to adulthood.