It appears that you seem to be denying the ability of a genetic mutation to account for a new species. In the anti-evolutionist world: Macro-Evolution. Let me give you a lovely little story.
I'm sorry, but, because I don't really have the time to explain all genetics concepts, I'll have to make the assumption that you have at least a basic knowledge of such.
Let's consider chimpanzees. Like us, their genes are stored in chromosomes. Also, like us, the genes of one chimp are generally in exactly the same order as the genes of another chimp, even if the two chimps are not related to one another. The same is true for gorillas and orangutans. Their genes are stored in chromosomes and within each species, the genes are almost always in exactly the same order. Now we come to the very important question. What about between species? If gradual, micro evolution is true we would predict that the genes would be in almost the same order, but because there has been a lot of time for rearrangement of chromosomes we may actually be able to see evidence of specific rearrangement events in the time since the two species had a common ancestor.
Let's, for the sack of illustration, number each gene. Here's the chromosome:
Gene1---Gene2---Gene3---Gene4---Gene5---Gene6---Gene7---Gene8---Gene9---Gene10
Say this is the chromosome from the chimp.
Now, examine the same chromosome in the gorilla. It would look something like this:
Gene1---Gene2---Gene9---Gene8---Gene7---Gene6---Gene5---Gene4---Gene3---Gene10
As you compare the two chromosomes it is fairly straightforward what happen to the hypothetical chromosome. Geneticists call this inversion.
It is this sort of thing that makes it clear to most biologists that the chimp and the gorilla have a common ancestor. Of course, the example is simplified to get the point across.
Variation in the gene pool can occur in such a way as just described. Could be a complete duplication of a chromosomes itself. Could be caused by some mutation, such as a point mutation, DNA replication error, duplication mutation, insertion, translocation, transposition. Or even by Intergenic gene conversion.
Now, back to the main issue at hand. How this relates to rational thought. All I am proposing is that by some method, take anyone that you see above, humans created the right gene sequence, to create a cascade event that eventually led to the creation of us having rational thought. And that, that mutation, in whatever form it might have come, is what I think the fall of man was. When we realized that we could realize.
We didn't evolve from monkeys. They are our ancestors. Way long back (35 million years ago) was a creature who we both shared as relatives. Just like you and you cousin have one set of grandparents as direct shared relatives.
Now, onto the question about chromosomes. A good one I must admit, but still an ignorant one none the less.
Do you know what the problem is with people who have down's syndrome? It's that they have 3 copies of the number 13 chromosome. This is caused by a translocation of the chromosome. As well, chromosomes do break off and recombine (also called, so cleverly, recombination) to form new chromosomes.
Onto the number of chromosomes. Yes, humans have 46. The great apes (orangutans, gorillas, and chimpazees) have 48. How did they achieve these two more chromosomes? The fusion of two ascrocentric chromosomes in the great apes to form a metacentric chromosome can account for the number 2 chromosome in humans - and accounting for the numeric difference in the number of chromosomes.
I have a nifty little diagram here that I would should you if this weren't over the internet.
Are their differences between us and the great apes? Of course. But only a 1% difference. Human banding patterns are almost identical to chimps' for 13 chromosomes,to gorillas for 9, and to orangutans for 8. In the rest of the chromosomes, almost all the same bands are present, but they are distriubted slightly different. The cause, for all you sceptics, is simply chromosomal inversation and transposons.