male/female ratio

The disconcerting problem in all things hacker - from the 1 in 20 ratio in Computer Engineering classes to the frightening absence of the fairer sex in badminton clubs, tech jobs and car repair shops.

Related to the opposing problem: finding males in aerobics, women's issues courses (sadly enough), and nursing.

In evolutionary terms, there is strong pressure for a male/female ratio of 1:1. If you have twice as many females as you have males, producing more male offspring is a much better way of ensuring your genes get passed on (your male offsping have a much metter chance of fathering more children themselves than a female child would). If you have more males than females, producing female offspring is beneficial - many of the males will not get the opportunity to breed, while all the females will. Equilibrium is reached at about 1:1, at which point having offspring of either sex is equally advantageous.

As Fluffy the Cat suggests, there is a strong selective pressure for a 1:1 ratio for many animal species, including humans, but that is not necessarily the absoute rule. The study of sex ratios is central to the biological disciples of demographics and life history. In many animal species, the basal sex ratio is not 1:1, and is so for easily explained evolutionary reasons.

For example, look at the elephant seal. This species exhibits extremely strong polygamy, where one male may have a harem of up to 20 females, which he jealously protects. Thus, non-dominant males may go years before being able to reproduce (read: defend a harem themselves), and during this time have zero fitness. Furthermore, each year that an adult male cannot reproduce is another year where he risks mortality for zero evolutionary reward. In this species, the sex ratio is roughly 4 to 5 females per male, and evolution dictates that it should be such. If you were an elephant seal, betting your genes on your offsprings' reproductive success, it makes sense to produce more females; they will reproduce without much difficulty. Producing a male is more risky, as the animal may never reproduce, but can carry more reward, as one successful male may produce hundreds of offspring. Thus, the best strategy to adopt is to favour female offspring in order to maximize your chances of passing your genes to subsequent generations, and throwing the odd male in there in the hopes of winning the lottery, as it were.

The male/female ratio in matriarchal societies (or, as in our case, societies which were once matriarchal) can be reversed from the Western norm in some fields.

For example, in the Philippines, where wives and mothers are expected to handle the family's finances, females consistently score better in Mathematics than males.

This means that in Math, Statistics, or Computer Science courses, we actually have more women than men. I remember when I was still an undergrad (early 90's) that there were only five boys to fifteen girls in our CS class. Looking over this year's freshman orientation (nearly 200 students), we've got almost the same ratio - 75% female, 25% male.

This doesn't spill over to the "manly" courses of Engineering or Physics, though, where the ratios follow those given above.

I'm just thankful that our women didn't grow up believing "Math is hard!"...