Sunday 6 February 2005

Pic of the day: At the outset, of course, they all look much like Winston Churchill without the cigar. (Screenshot from Sims 2.)

Genetics of seventh sons

There is actually a reason why a seventh son of a seventh son would be different from the line of the firstborn, and why the both of them are considered special. In fact, there is even a reason why it is the seventh son and not the seventh daughter that is special. It isn't quite as accurate as all that, but it still makes sense.

This is not about numerology and the supernatural, it is about genes all the way down. I'll leave the supernatural aspects to those who believe they have esoteric knowledge. Surely you would not look for that here...

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Now you see, the genes in a human cell are all tightly wound up in those spirals, double helixes as they are called, during reproduction. But if you unwound them, you would have these tiny fine threads all over your living room, so much DNA is there. It is little less than a miracle that it is all copied correctly every time a cell divides. And, as you have surely heard from others, sometimes there is a small slip. This is called a mutation, and if one of those happens in one of the reproductive cells and makes it into the next generation, that child becomes a mutant.

Actually, most of us are mutants. Sadly this doesn't mean that we can fly or all the other marvelous stuff. Most mutations make no real difference. First off, there are several codes that result in the same amino acid, and even if you change one amino acid the protein may have the same shape and thus do the same thing. Even if not, there is usually one other chromosome with the correct code, so your body will still work the same at least for the most part. But if a mutation becomes expressed, it is more likely to make you sick than super. In fact, a lot of spontaneous abortions and stillbirths are mutants. And boys are much more likely to suffer that fate than girls. Even if there are born more boys than girls, there are conceived even much more boys.

There is a difference between men and women when it comes to reproduction. All the ova, the egg cells, are made inside a baby girl before she is even born. It is still a long time before they mature, and things can still go wrong, but they are all right there, hidden safely inside her from before she comes out in the daylight. With boys it is not like that at all. Not only are the testes kinda exposed to radiation and everything, but the cells there start to divide at puberty, millions of them each day. They divide and multiply like mad, over and over again, day after day for as long as a man lives. (Although they do slow down a bit over time, thank goodness.) Anyway, this means that when you come as far as to the seventh son (which is probably at least the 10th or 12th child altogether), there has been thousands of generations of those little tadpoles already! All of them with a tiny chance to mutate. So such a child is almost certain to be a mutant. If he is born alive, the mutations are probably not all that bad. What's certain is that your last children are genetically more likely to be different from you than your first, and when you do this over a couple generations it can really add up.

Conversely, the firstborn is the one that has your genes almost unchanged, at least if you don't wait around for decades before having children. That's why for instance kings give their throne to their firstborn. To become a king in the first place, you probably did something impressive, like conquer a lot of land or stage a revolution against the former king. So you're probably strong and smart, and you want the next king to be as similar to you as possible, for the good of the kingdom or at least for the good of your family. With wizards and shamans and other weirdos it's exactly the opposite: The weirder your offspring, the more impressive. So you want to rack up as many mutations as possible before you pass on the torch.

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So that's it, basically. Simple as that. But why 7? Why not more? Well, apart from 7 being the holy number, there is also the practical consideration that you need to be born. In the wild, people rarely get that many children. No, seriously. Before we got all these extra vitamins and stuff, women often could not conceive again until their child was weaned or at least was beginning to drink less often. There simply wasn't energy enough to start a new child. Now that the problem is too much food instead of too little, that may be hard to imagine, but it still happens to some women. So even if you're not using contraceptives, having 7 sons is not a sure thing by any means. If you upped the number to 9 or 10, there simply may be too few of them to notice.