Sexual reproduction is fascinating for a whole bunch of reasons. In my general biology classes I bring it up fairly frequently for a variety of reasons. First, most students (and probably most people) are conditioned to think “sexual intercourse” when they hear “sexual reproduction”; you can get through your whole life without knowing it, but sexual reproduction is so much more than that. Second, there are so many different ways of reproducing sexually that it boggles the mind. Imagine if your sperm or egg had a slighty more interesting existence where it grew into a whole different type of “you” that had a job (different from yours) traveled (generally more widely than you could) and importantly, walked into bars, found mates and completed the cycle to form your child – this is only a slight athropomorphic exaggeration of the plant version of “sex” (don’t get me started on the fungal version). Third (and probably most importantly), a judicious use of the word “sex” in a classroom guarantees that you have their attention for at least a minute or two (and allows me to use my favorite rhyme ” “Barry White and low light”). Fourth, while sexual reproduction is immensely important for *populations*, its benefit to individuals is limited: its costly, can be dangerous (microbiologically and otherwise) and is not necessary to create offspring (animal example, plant example, fungal example). It’s a small evolutionary enigma.
Speaking of costs, how about that crazy burden placed on pregnant females of H. sapiens? Anyone else ever wonder how the hell that has worked for all these hundreds of thousands of years (some millions of years ago it was most likely a lot easier). What’s up with *that*?
So anyway, as if pregnancy weren’t pseudo-pathological enough, it doesn’t end there: fetal cells invade the mother’s body , including her brain and can be found there for years afterword. The easy thing to do here is to crack jokes about how kids get on Mom’s nerves, but there is another, Hallmark card type angle here that could be telling us something of the evolutionary advantage this (kids cells in Mom) could involve:
Recent research shows that these fetal cells rush to sites of injury in the mother and will change into a neuron or a heart muscle cell or whatever Mom needs. True, that is a mouse study. So here is a human study. An animal is an animal is an animal.
Ok, everyone all at once now: ahhhhhhhhhhhhhh, isn’t that sweet?*
* – there is a more sinister interpretation of this phenomenon.