Hey sorry to butt in, but I remember a while ago Der Trihs or HMHW or maybe Voyager had a really great writeup of how evolution was simply the state of existence of almost anything in the passage of time, including non living “things”. Anyone remember where that was?
Who among those who have done programming have NOT done one of these?: try everything and put it in a loop and discard the ones that AREN’T matching the desired parameters; exit loop when found
It’s brute force; it may seem klunky but the one thing it has going for it is that it is exhaustive and bloody freaking well WILL find the specified parameter sooner or later.
In the case of evolution it’s recursive; the loop never exits, the parameter is always tomorrow’s “will survive”.
Silverstreak Wonder, you have now demonstrated that you have pretty much no knowledge of evolution–either in theory or in fact–that did not leap fully formed from the typewriters of Duane Gish, (in the most favorable light), or Kent Hovind, (in the more probable view). As such, now that you have demonstrated a complete failure to actually understand evolutionary theory, you are done in this thread.
Feel free to open a new thread to discuss your beliefs, but there is no point in letting you hijack this thread with a lot of error filled drivel.
[ /Moderating ]
At the risk of sounding very very stupid:
In any population, spontaneous mutations in DNA arise through a variety of mechanisms, including chemical effects, random recombination and other unknown etiologies. While most of these mutations have little aparent effect, some provide a survival benefit on the individual (ie longer legs allow one organism to run faster and escape predators). Because those individuals of a given species that have a survival benefit are more likely to reproduce, those genes are more likely to become predominant in the population. Over time, the prevalent genes in a given population will undergo a shift which favors survival benefit in that population’s particular ecosystem.
Actually, our ahem “learned companion” SW did raise an interesting point.
We can now map a human genome, so I presume we could map the genome of, say, a bacterium or amoeba or some other organism that can exist as a single cell.
Is there a reason why we couldn’t synthesize a single-celled organism once we’ve mapped its genome?
If this is outside the scope of the thread I’ll be happy to start a new one in GQ.
Without reading any of the previous postings, here is what I think I know.
First, “theory” in this term means “an explanation for a process that is reasonably well understood and accepted as factually correct,” like the “theory of gravity.” It is NOT a theory in the sense of “an unproven idea that may be tossed out when new evidence comes to light.”
The “theory of evolution” was developed by Charles Darwin decades before he published his thesis in “The Origin of Species.” He did not publish until he got wind of the fact that someone else was about to publish the same ideas, and he wanted credit for his deductions. For years he did not publish both because he feared the backlash from religious society, and out of respect for his beloved wife, who was far more religious than he was.
Essentially the theory of evolution says that over time populations will adapt to their environment. Certain traits (let’s say the ability to hide from predators) promote the ability to survive and individuals within a population that express those traits are more likely to pass them on through their genes to the next generation. There is nothing in the evolutionary process leading to an “ideal” or more “advanced” state - evolution simply leads to traits that enable survival in a particular ecological niche.
Anti-evolutionists sometimes ridicule the idea that evolution could lead to the complexity we see in life today, saying “what good is a half-evolved eye?” But they are overlooking how evolution works. For one thing, evolution has been going on for a helluva long time, so a complex result isn’t really all that surprising. For another, because the evolutionary process is based on random mutation, the first recognizable “eye” may have been due to a mutation in a body part that was in use for something else or was simply harmless (evolution does nothing to get rid of characteristics that don’t interfere with survival). Also, it isn’t too incredible to imagine that some rudimentary cells became light-sensitive and this conferred an advantage, so the complex eye that we know today really could have evolved from an eyeless creature.
I know, or think I know, a lot more about evolutionary theory, but it is hard to summarize it in neat little paragraphs. Give me a multiple choice test on the subject, though, and I bet I’d score pretty well. I’ve read “Wonderful Life” and many other Steven Jay Gould books – Ask me about punctuated equilibrium and the Burgess Shale! (I’ve read Dawkins, too.)
I also know a bit about the personal history of Darwin. He was NOT the naturalist on the Beagle, he was a “gentleman’s companion” for the captain. Also, he came up with an explanation for the formation of atolls at a time when our ability to gather evidence on the subject was too rudimentary to prove or disprove his ideas. Since then, modern science has shown that he was indeed correct, and his insight into atoll formulation is considered one of the finest examples of pure deductive reasoning known in the world of science.
In that vein - I think a lot of people are under the impression that natural selection is the be-all and end-all of evolution methods, thereby discounting genetic drift, which, depending on population size, can be even more important.
We’re not advanced enough yet?
Wehave mapped out the genomes of some simpler organisms (this is not as trivial as you’d think - the largest bacterial genome is something like 10 million base pairs vs humanity’s 3.2 billion, the largest protist one has 670 billion).
Plainly put - DNA is not an instructional manual for human consumption. It’s more of a recipe book to be read by the machinery of a cell. IOW - you need a working cell to use DNA to make more cells, plain as that. We can already do this, tweaking DNA to get bacteria to produce new and unique bacteria. And one day we will have the nano-assembly capability to generate a new cell with non-cellular assemblers (why we’d want to is a different debate), but we’re not there yet.
This is all all think correct, but there’s one important thing missing: in organisms that have some way of combining genetic information from different individuals (sexual reproduction being one popular mechanism) most of the variation between inviduals is due to that mixing (you’d still need some mutations to get new gene variants, though).
It was supposed to be David Duchovny’s breakthrough movie, but he didn’t take. I think it was directed by the Ghostbusters guy. The premise was interesting, ut it couldn’t focus between being a zany comedy or a sci-fi flic, and it appeared just when audiences were getting tired and over saturated with cgi.
Decent timewaster, but not for repeated viewing.
There’s no reason we couldn’t but right now we are simply not capable. It’s an extraordinarily complex undertaking to synthesize then piece together that much DNA. Not to mention a living cell is far more than DNA. It’s RNA and organelles and cell walls, etc. As it is, the best we’ve done is insert small strands of synthesized DNA into fatty membranes in an attempt to make a protocell. Basically the simplest self replicating unit we can devise and something that could have occurred naturally in early shallow oceans. The guys at Harvard can explain this much better than myself:
Thanks. That’s exactly what I was looking for - whether limitations on current technology prevented it.
This isn’t a problem just for living things; we can’t synthesize most systems of complex molecules. We think of synthesis as taking a box of various elements’ atoms and putting them together like itsy-bitsy tinkertoys. But we don’t have the technology to do that at any sort of scale. We can create large quantities of molecules that are the product of various chemical reactions (say, dumping chlorine and sodium together in water to get a lot of salt in solution), but slapping together multiple end products at once without undesirable side products…nope, not yet.
On the plus side: if we ever get this, Star Trek-style replicators will be right around the corner. And there’s no reason to think that such a device, if we had one, could not produce a living cell (given an atomic or molecular-level mapping, not just the gene sequence). Matter is matter.
If only someone would write a few paragraphs on the subject. I would but unfortunately I don’t know how to use the Internet.
Well, not quite. A dead cell is chemically identical to a living cell, except that it’s dead, no?
No. Some sort of damage (physical change) caused it to be dead. At the risk of an unsupportable claim, I doubt there’s a mystical “cell soul” that makes them alive. Electrical activity is going to be the fudge point here, but I don’t think I’d claim that a cell that could be restored to life with a little electrical charge was really “dead.”
But your point is a good one nevertheless, and probably a more salient answer to the “why can’t we make one” answer than mine: the fact that we can’t synthesize a live cell is much less remarkable when you realize that we can’t synthesize a dead one, either.
Okay, without looking at anything other than the OP:
Because each organism is different, there will be certain individuals who are more likely to survive than others for a given set of circumstances: they may be stronger, faster, better at hiding, or more resistant to dehydration, cold, heat or any number of other adverse factors. Those that are more likely to survive to the point of reproduction, are likely to pass on the genes that code for their enhanced likelihood of survival to their offspring. Over many generations, this process of natural selection has a very gradual tendency to adapt organisms to their environment.
Over a long period of time, the organisms that have adapted resemble their ancestors less and less, and diverge into different species, that because of the changes in their genetic makeup can no longer interbreed.
There’s other stuff about mutations and asexual versus sexual reproduction, but that’s the very bare bones of it.
However we can synthesize viruses. In the Times Science Section today there is a fascinating story about fossil viruses that get lodged into our DNA, from invading our egg and sperm cells and thus getting reproduced along with the rest. Mutations prevent it from replicating on its own. However, scientists have gotten different versions, used textual analysis to find the original one, and synthesized the original virus - which can replicate.
That’s why I asked SW if he considered viruses as being alive. If you do, we have already created life from scratch.
Basically, natural variation and the effect of random decisions of what to pass to each offspring mean that some traits can be fixed (be the only variant found in a population - say, only blue eyes) or in the opposite way, eliminated entirely (no gene for blue eyes). This can occur without any selection pressure at all, just by random sorting, and much more so in smaller populations (so-called genetic bottlenecks)
The classic analogy is you have a bag of 20 black marbles and 20 white ones. You choose them randomly, and for each one, you put a marble from a large pile of that colour in a second bag, until you have 20 marbles there. Then choose randomly from that bag and put into a third. How many iterations before you only have a bag of one colour to choose from? What if you have 2 marbles in the first bag? or 2000 000? Now think of the marbles as population size, and the colours as traits they possess. That’s genetic drift in a nutshell