This is what seemed to me to be your main point, and I’d say you’re correct. Of course. Science is always a work in progress. Personally, I don’t think we’ll ever have all the answers. For an interesting view on the value of “neutral” mutations, see “At Home in the Universe” by Stuart Kauffman. It’ll make you think, that’s for sure.
Hey, dropzone:
<aside to wife>
Honey, load the fire pump with seawater.
Clever response, and you know your sf flicks, but for the record, triffids weren’t destroyed by seawater in Wyndham’s book, or in the good BBC adaptation of it from several years back.
As it’s been a LONG time since I read the story and have only heard bits of the BBC version, please reenlighten me on how the triffids were destroyed in the book.
Okay, that line of discussion does not belong in GD and I’m not sure if the upcoming belongs in this thread or the fundementalist thread AND it has probably been beaten to death before, but I don’t spend much time here so I don’t know for sure. If it has, then I apologize.
What is implied, even mentioned, but rarely concentrated upon in discussions of evolution is the absolutely preposterous length of time involved. Dismissing Bishop Ussher’s 4004 BC creation as fantasy and the “young Earth” theories as red herrings intended to support the fundamentalist vision while giving it a scientific veneer, the time we are talking about is immense, with plenty of chances for failure, although “failure” implies a consciousness and purpose behind evolution that is actually absent. Also forgotten is that most mutations ARE “failures,” from providing no benefit through reducing or even eliminating the organism’s chance of survival. It is a rare mutation, indeed, that increases an organism’s chances, but survival, meaning the organism lives long enough to reproduce, is so unlikely as to render any advantage valuable.
However, the unlikelihood of survival of even the advantaged organism provides the mechanism for both Gould’s “randomness” and his punctuated evolution. A young proto-giraffe’s longer neck might allow it to eat leaves further up the tree when it reaches adulthood, but might make running more awkward so it gets eaten before reaching adulthood. It is only when the mutation is combined with other internal factors, such as a morphology that counterbalances a longer neck and doesn’t slow the animal, and external factors, such as taller trees that require taller giraffes to exploit them more efficiently, that it can be considered successful. This provides the punctuation in evolution, where a group of mutations and other factors come together and allow an individual to be sufficiently advantageous to begin to dominate the gene pool.
Because potentially successful mutations are rare, the sweet spot where enough factors come together and make the mutations advantageous is rarer still and, because most populations are generally genetically stable, an awful lot of time is required to make evolution of more than the most rudimentary sort possible. Fortunately, the record indicates that we have had the required time. Most people have no clear understanding of just how long a billion years is. In addition, the number of organisms breeding during that period becomes unimaginable. A lot of reproduction over a lot of time is what makes evolution work.
Just a comment-a few years back I read a book by S.J. Gould, about the fossils found out in Western Canada (forget the name of the formation). Anyway, he talked about the very strange organisms, which supposedly died out in the Cambrian period. A few yesrs later, a biologist reported that most of these “extinct” creatures were still around! Its amazing to reflect how many ancient species are still with us-take the cockroach for example!
Just a few more points to smooth out the “all the old critters die out” error.
When a single deer develops a mutation that improves his speed, it doesn’t start killing its conspecific population. It breeds successfully with members of that population. Then its descendants do the same. Over a few hundred thousand years, all the members of that species which have regular contact and exchange with the population will be very likely to have the gene for faster running. If nothing else happens, the species is simply a bit faster than its ancestral population.
Suppose, however, that there is another variable. In one remote area there is another single deer with a genetic anomaly. He is able to gain fat tissue far more efficiently than most deer, when ample food is available. Currently that is a survival neutral characteristic in the area he lives, because food supplies are adequate in winter, and his added weight slows him down, and makes him susceptible to predation. His population gains a sparse showing of the genetic codes for fat production.
A few thousand years later, things dry out, and life gets tougher. Predators begin ranging over larger areas, and food supplies get scarce. Only the most suitable areas still support isolated populations of deer. Among most deer the faster gene is now critical, but even with it deer population levels drop. In lonesome valley, the faster/fatter population is much more able to survive. Among the lean/fast population smaller body mass is mildly beneficial to survival. Now you have two separate populations, with one common variation, and one distinguishing one. The difference is not enough to make the two populations mutually infertile, so they are still the same species. However, the lean/fast population has been drastically reduced in number, and genetic diversity. The fat/fast population has lost a smaller percent of its heritage.
Multiple iterations of this sort of mutation and consequence might well create two populations so different that they no longer willingly select mates from each other when contact occurs again. As random mutation increases the genetic diversity of the populations during favorable conditions, that diversity will not be shared between the two populations, even if they are no longer physically separated. Over a million or so years, large fat deer, and small lean deer might well become entirely isolated genetically without either one dying out. In later epochs, one type might survive in one region, and the other in different areas. Exactly when you no longer have the “extinct” ancestor species is really not significant to the evolutionary process.
Tris
Ok, someone may have already explained this but, the idea behind Darwinism (I’m not sure if parts of his version of evolution are still accepted, but this is what I learned in school last year): Naturally, animals overpopulate. This creates competition over who will get the limited food. Therefore, the animals most able to get the food and avoid predators will live long enough to reproduce, whereas the weakest will die out. This may not effect drastically the 1st generation, but as the # of genetically enhanced deer (or any other animal), naturally more of the inferior animals will be killed out until there are none. Then they hit the next plateau awaiting the next big thing to make those ones obsolete. With seperation and isolation, the old (if it survives) and the new versions will eventually become so different that they will become new species.