If I may interject a bit into this conversation with your permission...
Speciation, surprisingly, often happens instantly. DNA is wound up onto protein spools called chromosomes, to keep it organized. Every time the cell divides, there is a chance that this mechanism gets messed up. If the cell happens to be a reproductive cell (spermatozoa or oocyte) then the resulting sperm or egg cell will have a different chromosome count.
Most of the time, this is fatal, but not always. In fact, there are some often unfortunate conditions that occur when the extra or damaged chromosome is either the X or Y. However, sometimes the only thing that really happens is that the new organism can reproduce with the parent stock only with difficulty.
Once there are enough offspring to establish a small population, the "new counts" can interbreed readily, and often can no longer interbreed with the parent stock. This can take place in two generations. It helps if they're Southern. ];) (My family is from West Virginia.)
Perhaps six million years ago, this happened to us. In humans, chromosome 2 is clearly recognizable as chromosomes 2p and 2q in the chimp; all the others match up very nicely. So, humans have 23 pairs, chimps 24 pairs. They can interbreed, if at all, only with difficulty. (I won't use the Southern comment again.) ];)
So, the speciation, which is really genetic isolation, can come about very quickly.
Once a population is genetically isolated, the two groups drift away from each other. Recent work with moths show that obviously different species, by appearance, can come about in approximately six generations. It's a subjective measurement, but we all know of mutations that have made for very different-looking humans, and very different acting ones. Once in a while, this is a survival advantage, and takes root in the population.
Punctuated equilibrium is simply the recognition that thus speciation can happen quickly.
Since only perhaps one millionth of one percent of the vertebrates ever get a chance to fossilize, the "intermediate species" argument is rather a chuckle to me.
Remember when whales were the big thing with creationists? "Show me a whale that lived on land! Show me a whale only partially adapted! What was [i]this[/i] part used for, or [i]that[/i] part?"
Now, due to some fortunate finds in the Middle East, we've got intermediate whales running out the kazoo. But now creationists want the intermediates between the intermediates. As we find those, they'll want to slice [i]that[/i] pie too.
There is no such thing as an intermediate species. Or, put another way, they all are. We all are.
The avian/reptile business is another area of amusement. "This has features of its therapod (small biped dinosaur) ancestor, and beginnings of its bird legacy." The answer comes back "No it doesn't. It's OBVIOUSLY a true bird. Uh, with teeth. Um, and claws on the wings. Well, it's OBVIOUSLY just a dinosaur. With, ah, feathers and beak, and, am, extended forelimb bones to support a wing structure."
The more you learn about this, the more obvious it gets. And no evidence has been presented otherwise; I have investigated a great many creationist claims and found them not only wrong, but dishonestly so. They will sometimes admit the mistake, and show up on another list touting this mistake as "the unchallenged truth". THAT, more than anything else, is the aspect that annoys me, and I have personally caught a number of creationists doing exactly this.
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timeasmymeasure
no subject
Date: 2002-11-18 11:18 am (UTC)If I may interject a bit into this conversation with your permission...
Speciation, surprisingly, often happens instantly. DNA is wound up onto protein spools called chromosomes, to keep it organized. Every time the cell divides, there is a chance that this mechanism gets messed up. If the cell happens to be a reproductive cell (spermatozoa or oocyte) then the resulting sperm or egg cell will have a different chromosome count.
Most of the time, this is fatal, but not always. In fact, there are some often unfortunate conditions that occur when the extra or damaged chromosome is either the X or Y. However, sometimes the only thing that really happens is that the new organism can reproduce with the parent stock only with difficulty.
Once there are enough offspring to establish a small population, the "new counts" can interbreed readily, and often can no longer interbreed with the parent stock. This can take place in two generations. It helps if they're Southern. ];) (My family is from West Virginia.)
Perhaps six million years ago, this happened to us. In humans, chromosome 2 is clearly recognizable as chromosomes 2p and 2q in the chimp; all the others match up very nicely. So, humans have 23 pairs, chimps 24 pairs. They can interbreed, if at all, only with difficulty. (I won't use the Southern comment again.) ];)
So, the speciation, which is really genetic isolation, can come about very quickly.
Once a population is genetically isolated, the two groups drift away from each other. Recent work with moths show that obviously different species, by appearance, can come about in approximately six generations. It's a subjective measurement, but we all know of mutations that have made for very different-looking humans, and very different acting ones. Once in a while, this is a survival advantage, and takes root in the population.
Punctuated equilibrium is simply the recognition that thus speciation can happen quickly.
Since only perhaps one millionth of one percent of the vertebrates ever get a chance to fossilize, the "intermediate species" argument is rather a chuckle to me.
Remember when whales were the big thing with creationists? "Show me a whale that lived on land! Show me a whale only partially adapted! What was [i]this[/i] part used for, or [i]that[/i] part?"
Now, due to some fortunate finds in the Middle East, we've got intermediate whales running out the kazoo. But now creationists want the intermediates between the intermediates. As we find those, they'll want to slice [i]that[/i] pie too.
There is no such thing as an intermediate species. Or, put another way, they all are. We all are.
The avian/reptile business is another area of amusement. "This has features of its therapod (small biped dinosaur) ancestor, and beginnings of its bird legacy." The answer comes back "No it doesn't. It's OBVIOUSLY a true bird. Uh, with teeth. Um, and claws on the wings. Well, it's OBVIOUSLY just a dinosaur. With, ah, feathers and beak, and, am, extended forelimb bones to support a wing structure."
The more you learn about this, the more obvious it gets. And no evidence has been presented otherwise; I have investigated a great many creationist claims and found them not only wrong, but dishonestly so. They will sometimes admit the mistake, and show up on another list touting this mistake as "the unchallenged truth". THAT, more than anything else, is the aspect that annoys me, and I have personally caught a number of creationists doing exactly this.
===|===============/ Level Head