The Birds and the Bees...Literally.

Chapter 2 in The X in Sex

I mentioned in an earlier post that I was reading a book called "The X in Sex". Well, I finished it. And I know I say this about almost every book I read (and it's true!) but this was so interesting! Plus it was well written, and even funny in parts....I mean who can't appreciate a chapter entitled "The Duke of Kent's Testicles?" It's even more amazing to me because the subject of the book (minus the portions about testicles of course) is actively, at this very moment, doing all the things that I am reading about...inside every cell in my body. It's weird feeling to learn about my insides, and understand myself in such a way. I mean, there are processes going on in my body right now that...even with the aid of a book, I'll probably never understand. But somehow it's still me. How could I not know myself?!? Ha ha...It's just so weird...and awesome. I love it.

I learned so many cool things from this book that I am afraid if I try to cram them all into one blog it will be...sort of long and unfocused. So instead I am going to try to break it down into a few segments.

But before we start talking about the familiar males and females, X and Y and all of that, I thought it might be worth while to go into a little more depth on the multiple ways a living thing can create progeny. Bear with me if it seems a little redundant to the last post about this book. I'm going to try to be a little more specific.

Sex happens to be the one us mammals and many reptiles and birds use, but it is by no means the only (or even most efficient) way to produce offspring. And some of them are pretty incredible, at least as strange as our own way. As most of you probably know reproduction is broadly divided into sexual and asexual.
Asexual can be broken down into parthenogenisis, binary fission, budding, fragmentation and many other, but more obscure methods.
Fission and budding are mostly accomplished by bacteria, some viruses, and plants, and while they are interesting in their own right (and have many advantages), I'd much rather focus on parthenogenic species, because they are just so neat. They are animals that can reproduce without a male (or an opposite sex). Primarily they are mother/daughter species (although some can produce males once in a while, or be all male species) where the genetic material from the mother is passed directly and completely to the daughters. The classic pathenogenic species are aphids. But science has now discovered that some bees, lizards, hammer head sharks, Komodo dragons, and boa constrictors also reproduce this way!
When we move onto sexual reproduction things might become more familiar because there are boys and girls, but the methods of producing the XX/XY or ZZ/ZW (in birds and reptiles) can be totally foreign still! Besides our "normal" way of reproducing there are hermaphrodite species, like snails and many amphibians that can have both male and female sex organs at the same time (and fertilize their own eggs) or have the ability to change from male to female during their life cycle. Some species of frogs, when the ratio of male to female gets disrupted, can convert many of it's population to the less dominant sex to balance things back out again!
Or there is what is called "external fertilization" in contrast to our internal method. Salmon do this. A female will lay her eggs in the water, and a male will come by later and fertilize the eggs, and all the mating happens outside the body of the female.
Even when we finally get to talking about sexual reproduction where there are distinct males and females and the females are internally inseminated by males, the process can be wildly unfamiliar.
Humans (and all mammals) use genes to determine sex. XX and you have a girl XY and it's a boy. But there are many sexual species (with males and females) who don't use genes to determine sex! What do I mean? Well, here are two examples.
Bonellia is a kind of worm that lives in the ocean. They have males and females, but it is not genes that determine the sex of the offspring, rather it is the environment. The female creates sexless larvae that float around in the ocean. Eventually they drop to the ocean floor, and it is here that they decide what sex they will become. If the larvae falls and there are no other Bonillia around then it will become a female and root. If the larvae falls and there are other Bonillia around then it becomes a male, burrows into the side of the larger female, and essentially becomes a symbiotic...testicle! (Angler fish, as I mentioned before, also have a symbiotic relationship with each other.)
A second example is that of the Nile Crocodiles.They don't use genes or environment to determine sex, they use temperature! The sex of the baby crocks is determined by the temperature of the eggs during the middle of the third incubation period. If the temperature is above 34.5 degrees C or below 31.7 degrees C then the offspring will be female. But if the temperature falls within that 4 degree window, the babies will be male!

Often times we view the natural world with the idea that it is somehow perfectly designed, that there is an methodical simplicity in it, but I disagree. Especially when it comes to reproduction.  It seems to me life will try anything and everything. Males/females, females/females, males/males, male-females, males-then-females, non-sexed to sexed, non-sexual, clones, spores...etc. It reminds me of the game Boggle, where you use a discrete number of  letters to make up as many words as you can. So life has done with reproduction. Using the building blocks available, life tried every combination it seems,without bias. And the ones we are left with are the ones that worked better than the other possible combinations that are no longer with us.
Our human sexual reproductive ways have many advantages (primarily genetic diversity) and it is truly amazing how our bodies reproduce, but our strategy is far from perfect, and far from being the only way to get things done. And there are many weird, dramatic, and often unfortunate concequences embedded in our chosen methods. I will begin to discuss those in the next post.
But the take away point here is that there are pros and cons to every method of reproduction. None is perfect, none is flawless, and most of them are not even ideal. But the one thing they have in common (and the only thing they need to be viable forms of reproduction) is that they do in fact create survivors. You and I are one of them, and so is every other living thing on earth. Groovy. Yay for reproduction!