Common ancestry does not emerge from the inconsistent findings of molecular phylogenetics.
The spines of Australian echidnas and North American porcupines are remarkably similar.
If you define homology as resulting from common ancestry, you can’t then turn around and use that as an argument for common ancestry.
I’ve watched many Khan Academy videos over the years — sometimes just for fun, and sometimes to advise teachers on whether they are good tools to use.
The main evidence that Dr. Scott cites to argue that chromosomal fusions aren’t necessarily deleterious comes not from humans but from horses.