The diagram is originally from a 19 March 1982 Science article by Yunis and Prakash, entitled “The Origin of Man: a Chromosomal Pictorial Legacy”.

Thanks, Carl.

Very cool, huh?

Thanks for a very good presentation on a topic that confuses many.

I should have been able to get some of my other work done today, but no. I should have gone fishing, but I am doing that tommorrow.

There is an extra copy of chromosome 21 caused
most likely by nondisjunction during meiosis.

A trisomy also occurs on chromosome 13 and
18, with even more severe developmental problems.

The centromere remants could be the result of a neocentromere emergence, along with the inactivation of the normal centromere.

What evidence rules out a telomere-telomere fusion, after breakage of chromosome 2, which had aquired telomere ends for stabilization?

Thanks for the nice article and blog entry. I enjoy your writing immensely, except sometimes when I’m too tired of your having to explain evolution to people who don’t just misunderstand but also abuse the evidence.

You can take the example of chromosomal changes a little further. You mentioned healthy mice with fused chromosomes, but you should also know that developmentally normal people can have chromosomal fusions.

Acrocentric chromosomes have essentially empty short arms, going almost directly from centromere to telomere. When they fuse, that’s a Robertsonian translocation. When it’s balanced, the individual has fewer chromosomes but all the required genetic material, and matures normally.

This does complicate meiosis and make the individual less fertile, something that would be overcome if all individuals in a population had the translocation.

http://gslc.genetics.utah.edu/units/disorders/karyotype/robertsonian.cfm