h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Hmm..I remember reading the reason why peacocks have such lovely tails.

- The ones with the nicest tails gets to mate with lots of females.

-If you have a big flashy tail, and you haven't been eaten yet you must be a hard bugger, and all the ladies will fancy you.

Also we've probably been selectively breeding to have nicer and nicer tails. It's just a shame they can't make them quieter.

D.

It seems that any understanding of sexual selection has yet to percolate into the *science* of creationistism.

Also, the tail, when fanned out, is a pretty scary sight for a would-be predator. Each tail feather has large round whorls that look like huge eyes. For a predator, a creature with apparently multiple sets of huge eyes is a frightening sight. Many other animals use "false eyes" as a means of deterring would-be predators.

The peacock is not that defenseless after all.

But why do the females go for big tails? Shouldn't they go for the males that have a greater chance to survive, rather than going on something as irrelevant as a pretty tail?

A quick guide to sexual selection.

Sexual selection theory considers that females are selecting for the *health* of a mate.
The ornamentation that they base their mate choice on is an indicator of the underlying health of the male, since significant biological resources can be required to produce the colours/feathers/etc, and animals under stress from disease or parasites, or who are less skilled at finding food will have greater difficulty producing a good display.
Studies have shown that there is a definite correlation between the quality of the display and the underlying health of the animal in question.
If the burden the male carries does make it more likely that the male will suffer predation, then a male with a good display who can survive to breeding age is likely to be of above average quality.


In the initial stages of sexual selection developing, imagine a population of females who selected a mate based on their own criteria, with these preferences being hereditary. One (group) of them uses a particular feature of the male as a major factor in their choice. As long as there is a correlation between that feature and health, their female offspring should on average be healthier than those with a less decorated father, and male offspring will have a tendency to show the feature in question if they are healthy themsleves.
The greater fraction of the female population who display the preference, the stronger the selective pressure on males to display the feature, or fail to mate. If the choosy females do well, which they generally should do if the feature truly is a better guide to mate health than other signs that they can detect, eventually, the population can consist largely or solely of females with a similar preference.

So far, so good, but what can then happen is a process known as runaway sexual selection - even though from an external point of view there is clearly some inefficiency going on from the male's point of view, (a smaller, less expensive, but similarly accurate indicator would be entirely adequate for the species to produce quality offspring), if the female's selection strategy is simple 'Go for the guy with the largest feathers and most eye-spots', then there is pressure on the males to keep producing better and better plumage until they reach the equilibrium point where the extra cost (being slower to escape predators) balances the benefits (improved chances of mating).
From the female point of view, they just want the best mate, and it doesn't matter to them (from an evolutionary point of view) if 90% of males die before breeding, as long as the good ones tend to survive.

Is there anything above you think I should expand on?