When it comes to species, says biological anthropologist Rebecca Ackermann, “forget everything you learned in high school.”
In recent ancient DNA studies, almost “every time a new individual is sequenced from the human fossil record,” says Ackermann, “there’s some new piece of evidence for gene flow.”
Interbreeding may have been a common theme in human evolution, but it’s difficult to understand today, when ours is the only Homo species left. To better grasp our past, anthropologists like Ackermann have begun researching other animals that mate across classic biological species lines.
I wasn’t referring to common descent. I was referring to what is shown as a node in the phylogenetic tree (I e as a common ancestor). It might not be one organism. But a hybridisation event.
Depends on how much cross breeding happened. There are some studies on birds which point to a lot of hybridisation.
In such cases, perhaps the tree is not a useful model.