chromosome counts

A good figure comparing ape chromosome drawings (ideograms) for human, chimp, gorilla, orangutan appears at Indiana University BloomingtonThe numbers designate the numbering scheme for human chromosomes. In a karyotype, the chromosomes are arranged from longest to shortest, with the exception of the sex chromosomes, which appear in the lower right of the figure. In each numbered set, the human chromosome is on the left, and the corresponding chromosomes from the other apes are aligned next to it (in the order chimp, gorilla, orangutan). The banding patterns occur from staining the chromosomes to make comparisons easier. Note that human chromosome#2 aligns with 2 separate chromosomes from the other species, due to the chromosome fusion in the human lineage.Other rearrangements can be discerned by comparing the chromosomes, particularly inversions of some sections. Chromosome rearrangments usually don't have much effect unless the ends of the inverted segment occur within a gene region.The Human Genome Project and Chimp Genome Project are providing lots of data for determining the mutations that occurred in both species since they diverged from a common ape ancestor. As far as mutations in the human lineage that have potential ramifications for human intelligence, I'm aware of 2 so far. One is from a 92-base-pair deletion that caused a frameshift mutation, and is documented at: Just a moment...More recently, authors writing in the peer-reviewed journal Nature discussed a mutation that reduced the jaw musculature, which they said opened the way for larger skulls (and consequently brains) in the human lineage.Those mutations apply to all humans, and the mutations occurred long ago. If you want to learn about a more recent beneficial mutation in humans that is still limited to a small subset of the popultation, the apolipoprotein A-I Milano mutation prevents atherosclerosis. The Apo A-1 Milano mutation is at position 137 of the final protein, where arginine was replaced by cysteine. The mutation first occurred in Giovanni Pomaroli, who was born in 1780 in Limone sul Garda, Italy, and lucky descendants of his got the mutation. Search the web for a popular account about this mutation, "Mutant gene may curb vascular disease", by A.J.S. Rayl and Stephen A. Shoop, M.D., USA Today, March 2, 2000. For more technical info, a search at PubMed for "Apo AI Milano" resulted in 53 references.