I'm not saying he is stupid or a crank. I am saying that there is nowhere near anything like a serious consensus that his conjecture is much more than that, a conjecture.
I suggest you look for an example of complex behavioral change which scientists broadly agree resulted in speciation, and for which we can identify the genetic differences and correlate those genetic changes temporally with the behavioral changes. Note that this is not proof by any stretch of the imagination, but at least makes it somewhat likely. Good luck BTW.
Oh, I think I found someone claiming that around 1.9mya there was specific fossil species in our linage.
No luck. Did you read this part? They can't even agree on whether the two examples they have should even be in the Homo linage, let alone which one would be our ancestor if they where in our linage, or whether they crossed, or God knows what. Much more likely, the next significant find of a new species from that age will be considered a better candidate. And so it goes.... So to repeat, we don't know if we have an example of our direct ancestors from 2mya, and nobody that I know of is dogmatically claiming we do. It is all conjecture.
In addition, it is not yet entirely clear which of the two species Homo habilis and Homo rudolfensis led to the later species in Homo. The larger cranial capacities of the H. rudolfensis individuals lead some to think that later humans evolved from this species. Morphology of the facial bones of H. habilis, such as the shape of the cheekbones and the browridges, suggests that this species was the ancestor of later humans. (But see Homo habilis concerning the post-cranial paradox). (Click to see a representation of the two implied phylogenies)
Another debate centered around Homo habilis and Homo rudolfensis is whether or not these two species belong in the genus Homo or would be better suited in one of the other hominid genera. Some researchers feel that all species within the genus Homo should have characteristics, such as locomotor patterns, diet and body proportions, that make them more like modern humans than like the australopiths. These researchers feel that the characteristics of H. habilis and H. rudolfensis are more ape-like than modern, a conclusion that would remove them from our genus. This would make Homo a monophyly (all species evolved from a common ancestor), rather than a polyphyly (the species evolved from more than one ancestor) as it is now thought to be. Other reseearchers think, however, that moving the two species out of the genus Homo does not solve the problem since the specimens do not easily fit into the genus Australopithecus as currently defined. |
