How come there is no ape species more human like than chimps or bonobos? Why is there such a huge gap? You would expect to find living gradations of species leading up to human, right? There should be sub-humans and sub-sub-humans and sub-sub-sub humans walking around.
Since you say that we should expect to find "living gradations of species leading up to human," it seems that you're aware of the extinct species leading up to human, and that what you're really asking is why they're extinct instead of still with us like chimps and bonobos.
My own opinion is that there is insufficient evidence to provide any specific answers about why they went extinct. From Australopithicus afarensis and before all the way up to Homo neanderthalensis (Neaderthals), we can only speculate about the reasons for their extinction.
But the same is true of most extinct species. Why did the dinosaurs go extinct? Was it the asteroid? A period of unusually active volcanoes? Increasing competition from mammals? A combination? We don't know.
Thank you for that cut-n-paste from www.neogaf.com or wherever else copies also exist. Were I to give as much time and thought composing my reply as you did I'd have to close now.
You asked why there were no *living* hominid species more closely related to us than chimps and bonobos. That you said "living" implied that you understood that those more closely related are extinct. But now I can see that you don't accept that these extinct hominid species are related to us, so now you appear to be asking a different question. You appear to be asking why is the gap between chimps/bonobos and humans so large?
But if you do not accept that the extinct hominid species are related to us, why do you accept that chimps and bonobos are related to us when they resemble us even less?
There can be no specific evidence-based scientific answers for why most species went extinct, because the evidence just doesn't exist. We understand the causes of extinction and can engage in informed speculation, but that is as far as we can go. I don't even know why my Great Uncle Meier's line went extinct (other than the obvious "he failed to reproduce"), I can't imagine how we would ever determine why a couple million years ago the last australopithecine failed to produce descendants.
Most extinctions have occurred naturally, prior to Homo sapiens walking on Earth: it is estimated that 99.9% of all species that have ever existed are now extinct.
And it provides these references:
Wikipedia references writes:
Newman, Mark. "A Mathematical Model for Mass Extinction". Cornell University. May 20, 1994. Retrieved July 30, 2006.
Raup, David M. Extinction: Bad Genes or Bad Luck? W.W. Norton and Company. New York. 1991. pp. 3–6, ISBN 978-0-393-30927-0
I happen to own that last reference, and here's a brief excerpt:
David M. Raup in Extinctions: Bad Genes or Bad Luck? writes:
There are millions of different species of animals and plants on earth - possibly as many as forty million. But somewhere between five and fifty billion species have existed at one time or another. Thus, only about one in a thousand species is still alive - a truly lousy survival record: 99.9 percent failure.
Of all the species that have lived on the Earth since life first appeared here 3 billion years ago, only about one in a thousand is still living today.
Newman has also written the book Models of Extinction: A Review with R. G. Palmer, and chapter 2 is a detailed review of the data that went into formulation of extinction models and that provides support for the 99.9% figure.
I wasn't sure what level of detail you were looking for, so I provided information at different levels. The greatest amount of detail was provided by Newman's book Models of Extinction: A Review, it had fairly clear descriptions and even included presentations of data like this:
This book rolls up a great deal of information from many papers, so if you'd like to see the papers containing the data he used there's a long list of references at the end beginning on page 45.
I'm not trying to debate the percentage of extinct species with you, I just thought since you asked about it that you'd like to see some additional information. Is this somehow relevant to your contentions about human ancestry?
I'm still not sure what question you're asking. Are you asking why the gap between chimps/bonobos and humans is so large? And if so, then if you do not accept that the extinct hominid species are related to us, why do you accept that chimps and bonobos are related to us when they resemble us even less?
Also, you didn't give any indication whether you understood the explanation about the lack of evidence making it impossible to know in any specific way why a species went extinct. Did the explanation make sense?
I'm still having trouble understanding your position. On the one hand you say that there is no hard scientific evidence of extinct hominid species, and on the other you ask why they're extinct. Can you clarify?
You've been provided quite a bit of information already, but you keep asking for more. When someone says a species went extinct because they were outcompeted, which is all we can know given the paucity of evidence of specific events, you need to be specific about what you're looking for when you ask for scientific evidence. Do you think there are more reasonable explanations than competition? Would you like to see catastrophic events like volcanoes, earthquakes and floods included in the list of possibilities? Would you like to see more emphasis placed on changing environmental conditions? We could use some clarification about this, too.
The problem I see with your current approach is that while we understand you do not accept the information being provided, your brief dismissals give us no idea why and provide no hint whether you even understand it.