[QUOTE=Rucksinator]
So, theoretically, at some time a 48 chromosomed momma ape gave birth to a baby with 46 (or is 47 possible)? If so, was this 46 chromosomed ape able to breed with 48 chromosome apes, or did he have to wait for a female with 46 (or 47) chromosomes?
To put it another way, is it necessarily impossible to mate (with viable offspring) with an animal with a different number of chromosomes?
(Note: I attended private Christian schools until college, so my education is evolution, and any science closely related to it, is limited to what I’ve learned on the internet.)
[/QUOTE]
**Colibri **answered most of your question, but regarding 47 chromosomes…
Depends on how you do the counting. Most cells are diploid (they have chromosomal pairs), so you can’t have an odd number. Gamete cells are haploid (the chromomsomes are unpaired), and so they can have odd numbers. I usually think in terms of haploid number (23, for humans) to avoid the confusion. An odd chromosome number in a diploid cell can occur, but is usually considered an abnormality-- like people with Downs syndrome which is caused by an extra chromosome 21 in humans. People with Down Syndrome do have 47 chromosomes. There are also people with a diploid number of 45-- for example, girls with only one X chromosome. You won’t find any individuals with only a Y chromosome, though. Just another exapmle of why females are superior to males, I guess. 
Not all species have only diploid or haploid cells, btw. There are lots of species, expecially plants, that have polylploidal cells (more than 2 of each chromosome).