Something else about the phylogenic tree doesn't add up for me about which I don't have the background to articulate. I will think about it.
OK, I've been thinking about it. The tree, it seems, is based on an assumption of descent, rather than a scale of relatiionship, which is what it could be.
These are generated on the basis of sequence divergence of a single protein. . . correlates well with the fossil record. Geneticists have calculated, based on the known mutation frequencies of DNA, how long it takes for a single amino acid in a protein to be altered, so that each branch of the phylogenetic tree corresponds to the time since speciation, as well as the genetic similarities between organisms.
When you talk about speciation do mean the point at which two creatures are no longer inclined to breed in nature?
And remember study first; Internet second.
Aren't (blood) relatives usually defined as the people with whom you share ancesstors? IE, what does it mean to say that two critters are related, if it doesn't mean they have a common ancestor?
The scientific fact is that the tree deduced from the fossil record is the same as the tree deduced from comparing DNA.