Fortune of Conception

Moralists and theologians place great weight upon the moment of conception, seeing it as the instant at which the soul comes into existence. If, like me, you are unmoved by such talk, you still must regard a particular instant, nine months before your birth, as the most decisive event in your personal fortunes. It is the moment at which your consciousness suddenly became trillions of times more foreseeable than it was a split second before. To be sure, the embryonic you that came into existen...

 Hamilton's Model

Hamilton's rule is rb - c > 0. Here c is the cost to the giver's fitness (c fewer offspring because of helping), and b is the benefit to the recipient's fitness (offspring gained by the recipient from the help). Here again, "r" is a measure of the relatedness between giver and the receiver [...] Hamilton’s rule says that for unrelated individuals (r = 0) no benefit can overcome the cost of loss of the altruist's fitness (0 - c can't be greater than 0) and aid giving is selected against...

 The Theory of Neuromuscular Maturation

Believe it or not, it is only relatively recently that scientists have begun to appreciate the importance of babies' earliest motor activity. In the first part of this century, most researchers championed the view that motor development is largely innate, or "hard-wired." Struck by the remarkable consistency of skill acquisition, they argued that motor development depends solely on a fixed process o{ neuromuscular maturation (as their theory came to be called). with little role for practice o...

 Genes versus Hormones in Homosexuality

It is clear, however, that the cause of homosexuality lies in some unusual balance of hormonal influence in the womb but not later on, a fact that further supports the idea that the mentality of sexual preference is affected by prenatal sex hormones. This is not incompatible with the growing evidence that homosexuality is genetically determined. The "gay gene" that I will discuss in the ext chapter is widely expected to turn out to be a series of genes that affect the sensitivity of certain t...