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Well, well, well. You have many interesting questions and lines of thought unfolding in your questions. The long and short of it will end up being: "There is no short answer for your questions." You have struck to the heart of some of the meatier questions in biophysics, Evolution, Microbiology, Molecular Biology and a dozen other disciplines. In addition you open the door to some very interesting Science Fiction setups.
Preface: I've been having a curiosity attack for the last week or so, and I think you may be able to help. I don't expect you to spend beaucoup amounts of time replying to this, and maybe it's not even in your line of expertise (i think it does fall into the realm of microbiology, but i could be mistaken). So a simple note of recommended sources, or something would be more than helpful. See it's this weird approach to finding things out that i have, goes something like "If you want to learn something it's much easier to just ask someone who might already know, rather than bumbling around aimlessly" so here goes. Additionally i do realize that this probably isn't the usual sort of thing you get from these response forms. Heh heh
Query: Okay, if you buy into Darwin's ideas regarding evolution, this would dictate that living critters have to share/combine DNA (or whatever) in order to improve their species. Fine, but how did the practice of having two distinct sexes for each species develop to such a prevalence? Most (all?) of the live forms on this planet use, one way or another, a process of giving samples of DNA to a different member, who then generate an offspring (even plants swap pollen right?). How did this develop? Off hand the only single cell creature that I know how it reproduces itself is an amoebae, and i suppose the only way it could exchange DNA would be by eating somebody, or part of somebody recombining both structures into a new one, and thereby altering it's own internal makeup. How do all those other little guys reproduce themselves? This is assuming that larger multi-cellular creatures are just extravagant developments of those same little guys. Hey, another thing what do single cell critters eat?
al Final: So that's what i'm trying to figure out today, and every time I start on this train of thought I run into "Need more data" and don't even know where to start looking. Any suggestions or direction would be most appreciated.
Don't let reality grind you down
"Okay, if you buy into Darwin's ideas regarding evolution, this would dictate that living critters have to share/combine DNA (or whatever) in order to improve their species."
So what does this have to do with evolution? Nothing. There is no such thing as evolution -- not in the traditionally misunderstood sense. The anthropomorphic concept of life striving and making efforts to improve itself through the process of evolution is totally off-base. There is no Berliz course on evolution. Dale Carnage did not make a workshop called "How to make friends and improve your genetic structure." Not how it works.
- First of all, this statement on your part is misleading. The untangling of your misconceptions is a wondrous journey of learning in itself. Start by removing all traces of anthropomorphic assumption. Species do not have the intention of improving. A simplistic view of Darwin's ideas (as I understand them) can be paraphrased as follows:
For a species to survive a number of individual members of the species must survive. It's a numbers game -- nothing personal. The specific members that survive is not important.
For an individual member of a specie to survive it must first be born -- duh.
This means the parents must mate and survive long enough to birth the children.
To mate an individual should be not dead. Those who survive have a greater chance of mating than those who are dead. So all of you lonely hearts sitting around dateless consider this: at least your chances of getting a date a better than those who are dead.
Those that can mate make the babies.
Those babies who's mommies live long enough to birth them have at least a chance of living.
Those that live have a chance of survive.
Those that survive can try to mate.
Or put more simply: "If an individual is dead they are no longer contributing to the survival of the species."
Any understanding of evolution must come from consideration of each moment in time as a separate unit explainable within the context of itself -- at least in hind-sight. (Two points if you find that funny.)
"Fine, but how did the practice of having two distinct sexes for each species develop to such a prevalence?"
"Most (all?) of the live forms on this planet use, one way or another, a process of giving samples of DNA to a different member, who then generate an offspring (even plants swap pollen right?). "
- Great question for a science major to have. Be forewarned some bully professors will tell you by tone and gesture that your question is "like totally dumb -- every one knows that that's just the way it is." Do not be fooled. Your question is profound. The answer on its face is simple. But then as one keeps scratching the surface there is revealed layer upon layer of new insight and question.
"How did this develop?"
- This is called sexual reproduction. A mommy and daddy will each contribute a haploid cell (half the DNA complement) to an embryo -- egg & sperm combined into cell with full complement of DNA.
But what if the DNA was combined in different ways? What if a mommy ate the daddy? Ran some daddy cells through a special digestive process that isolates DNA into half its complement. Then combined that specially digested DNA with some of her own and created an embryo. The mechanism would be similar -- haploid combination of DNA. However I'm sure the dad and mom would find it different than the current scheme. There's a sci-fi plot. And/or a way out of the normal dating cycle. "How about a dinner and movie?" takes on a whole new meaning.
So where does this leave us?
- Some say it is too elegant a system to have developed from scratch on this planet. There is speculation that pieces of DNA on meteorites started the whole ball of wax.
That begs the question. Even if we accept that life on this planet did not did not evolve the DNA structure, then where did the meteorite that started the whole thing get its scum of DNA?
The system is elegant. The system is beautiful. And it is entirely possible to have evolved here or elsewhere. There is nothing I know of about DNA structure and function that would preclude its development from a primordial soup. On occasion it seems as if nature takes a perverse pleasure in making the totally improbable probable. So, as long as the process is not impossible and is only highly improbably I say it's a sure bet that sooner or later it'll happen. If not here than somewhere else. Given lots and lots of time, given lots and lots of space, given lots and lots of primordial soups in which to experiment it was certain to happen sooner or later. Then just head lice in an elementary school class it was sure to spread.
DNA is a wondrous koan. But like any koan there isn't a single correct answer. A macrobiologist will come to a different realization then a thermodynamicist, as will a immunologist, or a biochemist. Also like a koan, you will know when you reach a realization beyond facts and notions.
I don't happen to know anyone personally that I could point a finger at and say: "They have solved the koan of DNA." I did have the privilege of meeting some folks that I could say that about concerning special aspects of physics. It's not that I haven't known many biologist. It's just that rarely do they allow themselves the leisure to ruminate about such things sufficiently. The exigencies of day to day science stuff -- publish or perish -- keep one from delving too deep.
Here's an example of what I mean from a slightly different branch of science. When attending graduate school I played pool -- nine ball and eight ball. After a while my game developed to the point that I could run a rack or two. Meaning I could knock 15 to 30 balls in the pocket in a row without missing. This was good not great. One of the local "great" players asked me if I wanted to really play pool. In some discussion about what that meant the following piece of the puzzle was brought to light
If I was to become a great player he would tear my game apart. I would unlearn my stroke, I would unlearn how I positioned the ball, I would unlearn everything I thought I knew about the game. I would then rebuild my game from the ground up. He said that during this rebuilding process I probably would not be able to sink more than one ball in a row. My game would stink.
I wasn't ready to pay that price. I played pool to have fun with friends -- it was a social thing. I wasn't willing to sacrifice performance for perfection.
I don't know of any biologist willing to sacrifice performance for perfection. Performance is everything. Without performance a biologist will lose grants, teaching position, job offers, everything that goes with the occupation.
You see science has become an occupation. Science has not always been the cool and groovy money maker it is today. One can even dream about a time when people pursued it as an avocation.
Unfortunately pursuit of science as an avocation without training is worthless. But by the time one has gathered enough background to delve intelligently into the subject one has too much invested to chance the contaminating effects of a new understanding.
If any one with a bunch of money is paying attention do yourself a favor. Hire a team of well-trained but slightly this side of calcified scientist to work with some of the whackos for a year. If you need a list of whackos to pursue let me know. I have met a few that are worth the while. I don't trust their math and their experiments could use a bit of refinement. But, they are on to something; something that if not dismissed could make some one with a bunch of money a bunch of fame or a bunch of money or a bunch of both.