Female birds and mammals may choose to mate with multiple males, and their sperm can compete to fertilise one or more eggs within the reproductive tract.Ĭats, dogs and other animals can have litters with multiple fathers (the gloriously named " heteropaternal superfecundation"-even though the sound of it is really quite atrocious!). So, is the accusation of sexism levelled at Darwin really valid, and did this cloud his science? There is certainly some evidence that Darwin underestimated the importance of variation, strategy and even promiscuity in most female animals.įor example, Darwin-possibly as a result of a prevailing prudishness-placed little emphasis on mechanisms of sexual selection that operate after mating. Research since Darwin therefore reveals that mate choice is a far more complex process than he may have supposed, and is governed by variation in both sexes. And many fishes are sequential hermaphrodites, changing sex-and therefore mate choices-as they age.
For example, younger satin bowerbirds are frightened by the most vigorous male displays, while older females typically find these most attractive. Optimal mate choice is not the same for all individuals, or at all times in their development. In pipefishes, the males invest heavily by carrying the fertilised eggs until they hatch, and it is the females who compete with each other in order to secure the attentions of males. However, it may also be true that the ability of a male to manage such a burden is itself a marker of overall genetic quality and rigour. The peacock's tail is a handicap in most other aspects of its life-an impediment to flight and evading predators-save for the attraction of a female. Which strategy will produce most grandchildren?įemales may therefore select for traits in males that apparently have no other bearing upon their ability to survive. Females therefore face a dilemma: mate with a more attractive male and produce some highly attractive but otherwise less vigorous sons, or mate with a less attractive male to maximise the survival of those sons. In some species of poecilid fish, for example, male attractiveness is linked to genes that can reduce their survival.
But many other traits can be chosen because they are otherwise conspicuous and attractive yet may be a poor guide to overall genetic quality, or even misleading.įemales may evolve to choose mates with whom their offspring are less likely to survive, provided there are more such offspring as a trade off. For example, large antlers in deer are a good indicator of fighting ability, dominance and overall fitness. When animals choose a partner, their appearance, sound and smell can all be accurate guides to the survival ability of the prospective mate.
#Charms of music and female chitchat drivers
This maintained the focus on the dynamics of male dominance hierarchies, sexual ornamentation and variation as drivers of sexual selection, even if females sometimes did the choosing.īut do Darwin's ideas on sexual selection hold up today?
And he thought there was enormous variation among the males who battled for female attention by showing off stunning ranges of skills and beauty. He also downplayed the role of female variation in other animal species, assuming they were rather uniform, and always made similar decisions. Since the greater investment tends to fall on females, they are often the more selective sex (while males compete to be chosen).īut according to a new paper, published in Science, Charles Darwin's patriarchal world view led him to dismiss female agency and mate choice in humans. And embryos often need further investment in the body or outside. Eggs are relatively few in number-a large and costly investment-while sperm are small and vastly more abundant. There is an innate biological inequality, however.
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