So, what’s with this messy, painful business of giving birth to 7 lb babies through 1 lb body orifices? Examples of less strenuous forms of birth abound in nature. It turns out that the human form of birth lies at the end of a side road that starts with him putting his whatsis inside her yaya as a way of keeping the kids from getting eaten before they even have a chance to look like mom or dad. In many kinds of animals — most fish are a pretty good example — the prospective mom and the prospective dad meet up, and if both parties agree to do the deal, sperm and eggs are ejected right then and there, out in the open where everybody can see them. They are then mixed into a baby-making cocktail that is comfortably outside of the mother’s body, thank you, and there the resulting babies are left to fend for themselves. This is a very low-maintenance form of parenting, and sounds mighty appealing to anyone who’s had to endure 6 hours of hard back labor, or who is currently failing, as I am, to find that Rescue Heroes HyperJet that Santa is supposed to come over with in three weeks. Nonetheless, it has drawbacks. Since those babies are unprotected, lots of them die or get eaten by predators. So to have any babies survive at all, animals that make babies this way have to make lots of them, and when I say lots, I mean thousands and thousands at a sitting, only a few of which will survive.
Now, one or both of the parents can hang around and try to protect those fertilized eggs, and some kinds of animals do. But for that to help much, the parent has to hang around and try to fight predators, instead of running away themselves, and they run the risk of becoming lunch and leaving their kids unprotected. There’s another alternative , and it turns up over and over again in the animal world. That’s to make the kids in a way that allows you to take them with you. Instead of mixing the gamete (fancy biologist word meaning both sperm and egg) cocktail in the outside environment, the dad puts his sperm where it can get inside the mom, and the meet-up of egg and sperm happens internally.
How long the resulting babies stay in there, and how big they are when she finally gives birth to them, is something that varies from one kind of animal to another. The longer she holds on to them, the more protection she gives her kids from predators — sort of a head start. Most snakes and lizards, for instance, hang on to their eggs long enough to put a protective coating (shell) on a fertilized egg. But they still lay it outside the body long before it develops enough to look anything like a baby. Some of them keep fertilized eggs inside themselves long enough that when they lay them, what appears out the backdoor is a small version of the adult animal, able to run and hid from predators. This approach is called live birth, and it also turns up over and over again in the animal world, which implies that it’s a good solution to the problem of protecting babies while remaining able to run like hell.
You know where this is going by now. Like almost all mammals, we are live birthers, us humans, and true to form, never ones to do anything in a small way, we are the most extreme of live birthers. We keep our kids on the inside, sort of in pre-natal lockup longer than just about any other animal except perhaps elephants. And even an elephant baby can stand up and walk shortly after birth.
Why are ours so helpless? That’s another post.