People have 23 pairs of chromosomes, for a total of 46 chromosomes. Most apes have 24 pairs of chromosomes, for a total of 48 chromosomes. One very popular piece of genetic evidence for the idea that humans and apes have a common ancestor is that human chromosome 2 looks like two chimpanzee chromosomes that have been stitched together. As the evolutionary story goes, the common ancestor between apes and humans had 24 pairs of chromosomes, and it initially passed them to those animals that began evolving into apes and humans. The apes kept that number of chromosomes, but after the human lineage split off from the chimpanzee lineage, something happened to fuse two of the chromosomes, leading to only 23 pairs of chromosomes in humans. As Dr. Francis Collins puts it:1
The fusion that occurred as we evolved from the apes has left its DNA imprint here. It is very difficult to understand this observation without postulating a common ancestor.
This idea has been around for a long time, but I never put much stock in it. Why? Because even if human chromosome 2 is the result of two independent chromosomes being fused together (an example of which is shown in the illustration above), I don’t see why this can only be understood in the context of evolution. After all, we know that chromosome fusion events happen in human beings today.2 Thus, if human chromosome 2 really is the result of a fusion of two chromosomes, it could have happened early in the history of human beings. It need not have happened to some hypothetical evolutionary ancestor. Any event that restricted the human population to those who arose from the people who originally experienced the chromosomal fusion would then fix that chromosome in the population. A worldwide Flood in which a single family was saved would be one example of such an event.
Regardless of whether or not human chromosome 2 is evidence of common ancestry, it’s getting hard to understand how it could even be the result of two chromosomes fusing.
Continue reading “Chromosome Fusion? It’s Getting Harder and Harder to Believe.”