This offers the suggestion that females should be more “choosy” because of the amount of investment, and should search for the male with best fitness and food genes to pass onto her offspring, whereas males should be more competitive with each other (Trivers 1972). In contrast, a male human could impregnate any reproductive age woman who is fertile, and therefore could produce a large number of offspring.

In theory, a human female can typically have one offspring in nine months, this limits how many children she can have. In that case the female investment outweighs the male investment. On the other hand, the minimal obligatory parental investment for a human female is copulation, nine months of pregnancy and delivery. The minimal obligatory parental investment for a human male is the effort required to copulate. It is held that parental investment starts from the point when the male and female copulate and the egg is fertilized. Anisogamy refers to a form of sexual reproduction involving the fusion of two dissimilar gametes. This is an example of anisogamous’ sexual reproduction.

The female gamete, the over, is large – compared to the sperm- scarce and it costs a lot of metabolic energy to produce. The sperm expenditure theory is the amount of reproductive effort spent by a male on a given ejaculate. The male gamete, sperm, are small, unlimited and cheap to produce.

It involves the formation of gametes, in the case of virtually all multicellular animals this is the sperm and the ovum. Sexual reproduction is a process that creates a new organism by combining the genetic material of two organisms.

Evolutionary arms race sexual conflict