Re: Do you believe in God?
Hopefully this can address a few issues:
It goes: Kingdom Phylum Class Order Family Group Species.
(a fun mnenomic to remember it is: Kings Play Chess On Fine Ground Sand ... ... ...or, ...King Phillip Came Over For Great Soup)
So, dogs are in the animal Kingdom. Wolves are in the dog family. 'Dog' is actually a Family, not a species. All of the dogs that we have which can breed with one another to produce viable offspring are in the same species. The fox is in there, also in the dog Family. So a horse is in the Animal kingdom, but not in the dog Family, and the horse and dog end up in different Species. So a horse and dog can't breed to produce viable offspring. Similarily, even though the fox is in the dog Family, they cannot breed with poodles to produce viable offspring. That's because poodles and foxes are not in the same species. They are however, in the same Kingdom (the Animl Kingdom), Phylum, Class, Order and Family (the Dog Family). But after that, their evolution drifted apart; the fox and the domestic dogs got separated to the point where they fell into different Groups, and different Species.
It may seem that evolution is not taking place in our domesticated dogs because of all their funny shapes and sizes yet they still can breed with one another, but you have to keep in mind that foxes and domestic dogs cannot breed. It's kind of like humans: a successful woman lawyer from NY can indeed produce fertile offspring with a fisherman from India, and this is because they are in the same species (homo sapiens). But other primates like chimpanzees cannot breed with people, even though people are primates too. (we are primates; I just forget where that falls under Kingdom...P.C.O.F.G...Species)
Felix has some good arguments about the Bible influences on the great scientists though. Also, I agree somewhat about geniuses today. I believe, however, that there are loads and loads of geniuses today (simply because the population is so much larger today), but these geniuses are simply playing piano very well, or playing chess or some other triffling show-off endevor that isn't helping humanity along at all. The real important ones have been dead for a few hundred years and few have yet touched them.
However, you are wrong about the guppy fish. If we had a pool of them in our lab, we could put a wall between them and introduce predators and new food supplies, etc into one of the sides and leave the other side alone. We'll call them A and B sides. Well after a long time (many generations of offspring), the guppy fish in side A could be put in with the guppy fish in side B and they will not produce viable offspring. They will have become two different species. This process is called speciation (when 1 species undergoes evolution to become 2 separate species). As noted in posts above, a defining characteristic of a species is that its' members must be able to produce viable offspring--offspring that are fertile. So for example a horse and a donkey can breed to produce a mule. But the mule is always sterile. So horses and donkeys are said to belong to separate species.
Now, you could say that science is tinkering around too much by introducing new predators and food sources into the pool in the lab, and you can get whatever results you want using science. But this sort of thing happens all the time in nature. A new pest or predator arrives, and the species changes accordingly. It's not like the scientists are going in with needles and changing the genes themselves. The guppy fish are becoming 2 different species on their own, and this happens in nature.
How evolution works (the very brief gist):
Random mutations occur in all of us all the time. Mutations are sequence errors in a DNA molecule. The DNA is damaged and it self repairs, but not always successfully. (If you break up some DNA in a test tube it will reassemble itself, but not always perfectly). Most mutations in our DNA are either useless or harmful (for example, a gene that codes for an incomplete protein which makes cytoskeletal fillaments too weak). But, every now and then a benefitial mutation comes along. Only mutations in gametes (spermatazoa and oocytes/egg and sperm) get pased on to the next generation.
One such mutation might make a fish's body be more slender than the other fish. It sounds kind of bad...sounds like a specific protien is not being produced anymore in the whole set of offspring from this one particular fish. Then, these slender fish just happen to not get noticed or favoured by predators. Predators in this area only like to eat the bigger meaty fish. So many of the bigger (normal) fish are getting eaten while thses little slender ones are being ignored, and they reproduce ALOT producing more offspring with the very same mutation. As time goes by, with more and more generations of offspring, we see the little slender fish are in huge numbers and the once normal sized fish are dwindling. Eventualy, the whole darn population is slender and little.
This is what Darwin called descent with modification, or evolution. Each offspring is a little wee bit different from some random mutations (though he didn't know about how this happend exactly; he didn't know that it was mutations in DNA which was unheard of at the time). Then, the mutations that happen to be the most benefitial get their numbers of allels increased in the population. The newer, more suitable mutant offspring run the show and hog the resources while the 'normal' population misses out.
I won't get into speciation in great detail, but it basically involves an environmental barrier of some sort. Like, a storm carries some members of the population over to a new area, and they can never go back to the main population. Each group on either side of the barrier begin to evolve differently until a new species emerges, like I described with the guppy fish. One of the fluke members from the 'West' side has a benefitial mutation that is favored for the new environment. On the 'East' side, that same mutation COULD occur in another fluke individual, but the environment is different from the West side. So the mutation only helps out in the appropriate environment. For example, on the West, the only food source (for the fish who landed here via the storm) is poisonous but some random lucky mutant can make an enzyme that can turn the poison into something harmless when digested. On the East, this same mutation COULD appear, but there is no poison here, so no big deal; this mutation is not favored. On the East, other mutations are more benefitial so they are getting replicated.
The East and West end up with such different mutations taking over in their areas that the animals are now radically different. In fact East animals cannot even copulate with West animals now. Thier breeding parts just don't fit together, or the sperm and egg don't fuse properly, or the offspring dies as a blastomere without developing further. There are others, but the point is the 2 populations (East and West) of fish can not reproduce with one another anymore. The important thing to note is that several genertions ago, they WERE able to reproduce with one another. Thus, a new species is formed.
So why don't domestic dogs turn into seperate species after all these years and why don't Americans and let's say Africans become different species? Well, I think the answer is that NO ONE IS KILLING US OFF, WE ARE AT THE TOP OF THE FOOD CHAIN. IN AFRICA, IN AMERICA, ALL OVER THE WORLD NO ANIMAL IS HURTING MAN ENOUGH. Thus, there are lots of new mutations showing up in all of us, but the major difference from other animals is none of the unfavorable traits are being killed off in humans. Normally, in nature, some predator would kill off every last one of us leaving behind only some benefitial mutation. Notice anything funny about our domesticated dogs? That's right; they stick with us humans (who are under no pressure to change into new species)! We've been taking care of those dogs for a long time. Nothing major is preying on or wiping out our domestic dogs.
Well, this thread is long enough; thank you for reading. The capslock above was not to intimidate, but rather highlight what I think the answer is. This is why humans and domesticated dogs don't appear to be evolving into new species. Maybe we've even 'stoped' evolving (idk, guessing here) for a relatively brief period due to our place at the top of the food chain with nothing to wipe out the weaker. When someone is born with sickled red blood cells, no one takes advantage and eats that guy. He is left to reproduce freely. His DNA doesn't get wiped out like in normal evolution. But we still spent about 2 billion years evolvinmg from prokaryotes (bacteria, single celled). This is true despite any little trends we notice in the past few thousand years.
Edit: fixed many spelling errors. Also wanted to note: Darwin had a child with his cousin, and was wrong about some things. Nonetheless, he is considered to be the most important scientist next to Newton.
Also, there are other forms of genetic variation that occur when allels cross over in cell divison, but I just wanted to focus on mutations, environment and predation which I think are the most important parts.
