Ambidextrous

If symmetry is such a good thing in nature, why are we always dominant in one hand? And to what extent are other animals dominant on one side? And why does one side of the brain therefore develop more than the other? Is it better to use all the brain juice to make one a lot better rather than split and divvy it into smaller amounts for each side?

On a related note, symmetry is, of course, linked to biological appeal in both humans and animals. The more symmetrical, the more attractive to a mate, in principle. So here's an interesting little tidbit:

Biologist John Manning measured a number of features of women's bodies, including the size of their ears, and the third, fourth and fifth fingers of each hand. He repeated these measures periodically, over some months, with thirty healthy women between the ages of nineteen and forty-four. The results confirmed that the symmetry of their body increased by 30 per cent in the twenty-four hours prior to ovulation (confirmed by a pelvic ultrasound. In other words, their ears became closer together in size, as did the corresponding fingers of each hand. So women are most symmetrical at the time they are most likely to conceive.

-- From The Human Face by Brian Bates (a terribly interesting book that I have on my own bookshelf)