“The goal for every female animal is to find a mate with sufficient genetic quality to make a good husband, a good father or a good sire. The goal for every male animal is often to find as many wives as possible, and sometimes to find good mothers and dams, only rarely to find good wives. The sex that invests most in rearing the young – by carrying a foetus for nine months in its belly, for example – is the sex that makes least marginal profit from an extra mating. The sex that invests least has time to spare to seek other mates. Therefore, broadly speaking, males invest less and seek quantity of mates, while females invest more and seek quality of mates.”
“Males act as a kind of genetic sieve: only the best males get to breed and the constant reproductive extinction of bad males constantly purges bad genes from the population.3 From time to time, it has been suggested that this is the ‘purpose’ of males, but that commits the fallacy of assuming that evolution designs what is best for the species.”