A friend told me yesterday that he was raising another man's children with his girlfriend. The biologist in me for a moment reeled in horror, protesting that this made no evolutionary sense. Gametic blasphemy! But that didn't sit right and felt too severe. Below is my more thoughtful take on the subject. I conclude that it is indeed quite a logical evolutionary thing to do...
We think of evolution as the continuation of fit traits into the future. But this process exacts a heavy toll - if you measure the ratio of those killed against survivors bearing those traits. I'm sure someone has run the numbers on how many 'failed experiments' in life had to occur before the bird could fly or the human could develop logic. Richard Dawkins introduced the immensely useful term 'meme' - a unit of cultural inheritance. Basically a meme is the cultural equivalent of a gene (a unit of genetic inheritance - according to Mendel's early definition).
Why does it make sense that my friend promote the genetic endowment of another man? Simple. Because insofar as humans are concerned the meme is at least as important as the gene. Why? We typically think of power as the ability to influence. In the jungle, strength, speed, antler size, feather color and so forth allow a beast to influence female mating behavior - the main criteria that matters. Genetically, this translates to the ability to influence the future of the species - but only in a local fashion; the beast must be present to spread the genes (or at least have once been present to have released the genes).
Now back to the humans. If genes are limited by the proximity of their owner, memes are not and can travel farther. And they do not require the willing participation of the receiver (presumably genetic mating involves some kind of decision making (usually)). Consider how easy it is for a director to make an entire audience cry or laugh in unison; or the power of propaganda or advertising to shape buying decisions. This is a funny idea. I repeat, the higher cognitive functions are more easily manipulated than the more primitive (sexual) ones. This means war!
The war of memes is the battleground of humanity - a separate topic for another time. Suffice it to say here that to promote one's influence into the human future requires lots of memes. Meme soldiers. After all, what animal besides humans can be influenced by memes about attractiveness? So memes CAN control genes - to some extent.
Interestingly, what I'm suggesting is that it's easier to fool someone about an idea than it is to trick them to mate with you (try it sometime and let me know if you agree)! I'd love to conduct a study on this, but for now it remains a strong hunch. Why? Well, ideas are cheaper than creating biological parts: they spread farther and they cost less to produce (if you're already a human - never-mind the cost of actually BECOMING a human). Therefore it makes sense (cost/benefit fashion) that humans would work this out as a fancy new raw material of influence. If a new material that is superior in every way comes along (say a lighter, stronger concrete; or artificial spider silk), a company will use it. Same principle at play here from an influence perspective.
So while a geneticist might complain that my friend is ignoring some intrinsic evolutionary responsibility to his gametes, I would suggest that the raising of another man's progeny does make sense from an evolutionary perspective. If the game is about influencing the future toward the direction of one's own* image *then bending that future by memes makes at least as much sense as sculpting new flesh from one's loins.