Monday, January 13, 2014

Five alternatives to human reproduction

I tried never to miss a Star Trek episode until midway through Voyager. There were several reasons for this, but the show hardly even daring to nudge the envelope was the most important. Especially when it comes to science, Star Trek could have and should have been at the forefront.

And an alien giving birth from the back rather than the front… just did not quite cut it for me. Not when there are so many more unusual methods of reproducing.

1. Parthenogenesis

The women in David Brin’s Glory Season don’t need anyone else’s genetic input for conception, except during a certain time of the year—the titular season. During this time, they can choose to mate, though of course the children produced in this way are likely to be treated differently from those conceived in the more common method.

Suzy McKee Charnas’s Motherlines is similar; the all-female society of the Riding Women would have died out long ago if the women weren’t able to give birth to genetically identical daughters, maintaining their ancestral Motherlines.

The problem that Charnas illustrates in the novel, though, is that such a society won’t have much variation (unless mutation is much more frequent than it is in real life). Hybrid vigor will be unheard-of, and a population without genetic diversity will be that much more vulnerable to infectious diseases.

And it will be that much more difficult for people to be individuals when it comes to thought or belief or behavior as well. If identical twins are sometimes dressed alike, given similar names and expected to do the same things, imagine what it’s like for girls who know that they are doppelgangers of their mothers and grandmothers, all the way back to the first generation.

2. Mitosis

There was an Outer Limits episode where an astronaut, after exposure to something mysterious in outer space, started budding off an extra finger from his hand. He soon realized that this was just the first part of a whole new body—in other words, he was slowly but surely producing another copy of himself.

Mitosis, like parthenogenesis, doesn’t result in as much genetic diversity as sexual reproduction does, though this isn’t necessarily a bad thing if the parent copy has valuable but recessive traits that might be lost otherwise. It could also be much more convenient — look at how hard animals (and people) work to find suitable mates.

Not to mention that budding, a la yeast cells, might be a whole lot less painful than giving birth.

3. Prions

In real life, prions scare me as much as they fascinate me. There’s something insidious about strands of protein (which technically aren’t even alive) gradually corrupting the normal proteins in your brain. But to take this concept a few steps further, what if people could change others into copies of themselves?

As a long-term method of reproduction, this would carry the same risks as mitosis or parthenogenesis, but as a short-term deal, it could have some very interesting uses. I’m imagining a hostage crisis situation where the terrorists don’t realize is that one of the hostages is a prion, and being exposed to her is altering them by the hour.

4. Egg-laying

I like the indifference of most fish and amphibians — lay eggs, wait for them to be fertilized, go on with life. Of course, this is a viable strategy because they produce offspring in such huge numbers that the death of most of them isn’t a tragedy or even a problem.

Though that could apply to a lesser degree with a humanoid race as well. If each female produced, say, half-a-dozen offspring each breeding season, she wouldn’t need to raise them all to adulthood. She could instead abandon them to compete over limited resources, such that only the strongest survived. And if it didn’t, oh well, there would always be next year.

For this to work, though, egg-production, fertilization and any necessary gestation shouldn’t demand too much of a female. In mammals, so much of the female’s resources go into developing the young that naturally fewer of them are born, and those are nurtured and protected. It doesn’t make reproductive sense to devote nine months and one’s physical health to producing a human infant, only to drop it by the wayside.

Unless someone else is prepared to bring it up, which is a whole ‘nother reproductive strategy a la the cuckoo, and developed perfectly in Bernard Taylor's brilliant but out-of-print horror novel The Godsend.

5. Hive insect reproduction

I remember when I first learned what exactly worker bees — the uniformly female, non-reproducing members of the hive — get out of this arrangement. Bee genetics are such that, by allowing the queen to devote all her time to egg-laying, workers actually pass on more of their genes.

If a worker bee mated and laid eggs, her offspring would share 50% of her genes. But when she helps the queen to do the same thing, the queen’s offspring — the worker bee’s sisters — share 75% of her genes. Therefore, it makes sense for the worker bee to want more sisters, rather than children.

As a result, this is a very viable reproductive strategy and I wouldn’t mind using it at all (as long as I was one of the workers, because being stuck doing nothing but producing child after child is not my idea of a good time).


Loren said...

Budding isn't very common in the animal kingdom. Some cnidarians do it, but that's about it.

Something like it is common in plants and fungi, however. Their root systems can spread over large areas, sprouting numerous stems.

Strictly speaking, the "roots" of a fungus, its mycelium, are its main body, while the "stems" are fruiting bodies that make spores, like mushrooms.

Loren said...

Egg laying has the problem that the egg must contain all the food for the developing embryo/fetus. That means the baby can't hatch as big as it could if born alive.

The largest egg by relative size is laid by the kiwi bird of New Zealand, and it's a tight squeeze. Though the kiwi is about the size of a chicken, its egg is 6 times bigger than a chicken's egg, and up to 1/4 of its mother's body weight. The mother kiwi must eat 3 times her usual amount for a month, then must fast a few days just before laying her egg. The baby kiwi takes 2 to 3 months to grow inside the egg before hatching.

Another sort of variation is between many small offspring and a few big ones. We as a species are at the few-big-ones extreme, as are most almost-sentient species, like apes, elephants, and dolphins.

Sian said...

I must admit, prions was not something I'd ever thought of. Possibly the coolest idea ever though.

Unknown said...

Thanks for a very humorous exposition about various forms of reproduction. Very astute! Also, it's good to remember 'Star Trek Voyager', which like 'DS9' never seemed to get the acclaim it should have. -K. Griffiths

Sarpedon said...

I've always wondered if it could be that a monster would devour the flesh of its defeated enemy, and its genes would somehow work its way into the eggs or something.

Of course, that wouldn't really make sense in that the weaker member would get its genes passed on the same as the stronger one. Would have to be pretty artificial