Quote:
Originally Posted by Boggwin Bramblefoot
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From wiki huh? Nice. My mistake I meant to say Donkey and not mule. In a way you proved my point. Let me explain. I am sure you won't understand, but here it goes.
There is no scientific evidence that a species can change the number of chromosomes within the DNA. The chromosome count within each species is fixed. This is the reason a male from one species cannot mate successfully with a female of another species. Man could not evolve from a monkey. Each species is locked into its chromosome count that cannot be changed. If an animal developed an extra chromosome or lost a chromosome because of some deformity, it could not successfully mate. The defect could not be passed along to the next generation. Evolving a new species is scientifically impossible. Evolutionists prove that getting a college education does not impart wisdom.
When your dog is going to have a litter, don't worry that she will have a litter of monkeys or cats. She will always have a litter of puppies. The fact that she will have puppies was determined when her chromosomes joined with her mate's chromosomes at conception. You see, a dog has only 22 chromosomes, whereas a monkey has 54 and cats have 38. Half of the total number of chromosomes are contained in the female reproductive cells and half are contained in the male, so the exact total number is brought together in the offspring.
Humans have 46 chromosomes. This chromosome count is a steady factor. This determines what is called the "fixity of species" because the chromosome count doesn't vary. People always give birth to people. Dogs always give birth to dogs, etc. The genes can produce variety within the species but cannot result in a different species. Genes allow for people to be short, tall, fat, thin, blond, brunette, etc., but they are still all human beings. The chromosomes make crossing of the species an un-crossable barrier. This certainly would hinder any evolution. Dogs cannot breed with cats. This fact stops evolution dead in its tracks.
Sometimes two species are close enough to crossbreed, but the offspring are usually sterile. This is the case when horses and donkeys crossbreed. A male donkey (jackass) and a female horse (mare) will produce a mule. Farmers often preferred mules as work animals prior to the development of the farm tractor. A hinny is the offspring of a female donkey (jenny) and a male horse (stallion). The hinny and mule usually cannot produce offspring. These animals show that evolution is not possible.
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I'd like to thank you for this question. No, seriously. I had no idea what the answer was, and this is actually one of my fairly serious hobbies, so I started digging.
The answer to your questions is that chromosomes are not completely fixed. There are several ways for a particular gamete to change chromosome count. It's fairly technical but it basically boils down to that sometimes the two parts of a gamete don't split successfully (non-disjunction) and sometimes two chromosomes that are not part of a pair get stuck together (translocation).
The great apes all have 24 chromosome pairs. We, of course, have 23. There is no way to know for sure whether the great apes added a chromosome or humans dropped one, but the general thinking is that if the majority of species within a group (we group with great apes at the family level, hominidae) have the same number of chromosomes but another varies by one, it is likely that species is the one that varied. Ergo, human DNA was probably subject to translocation which reduced our chromosome count from 24 to 23. It seems likely that there was some pattern highly susceptible to translocation in one of our predecessors.
Interestingly enough, humans are a very inbred species compared to the other great apes. A small population of chimpanzees will apparently reflect as great a genetic diversity as all of mankind. You have, interestingly enough, hit upon the answer to why there are no 80% human great apes--the mutation that led to homo sapiens could no longer breed successfully with other closely related species.
It may go without saying, but gene mutations of this sort are fatal and almost always sterile. However, it's not extremely rare. In the last 17,000 years or so since humans began domesticating animals, we have created domesticated species whose chromosome counts vary from their feral ancestors.
I like it when I learn something new. I like it a lot.