An interesting article by Seth Borenstein on a new discovery related to human evolution raises a fascinating question. The discovery is that two previously alleged ancestors to modern humans, Homo habilis and Homo erectus were actually contemporaries and lived in close geographical proximity to each other. Here are some excerpts from the story:
The discovery by Meave Leakey, a member of a famous family of paleontologists, shows that two species of early human ancestors lived at the same time in Kenya. That pokes holes in the chief theory of man's early evolution -- that one of those species evolved from the other.
Leakey's find suggests those two earlier species lived side-by-side about 1.5 million years ago in parts of Kenya for at least half a million years. She and her research colleagues report the discovery in a paper published in today's journal Nature.
The paper is based on fossilized bones found in 2000. The complete skull of Homo erectus was found within walking distance of an upper jaw of Homo habilis, and both dated from the same general time period. That makes it unlikely that Homo erectus evolved from Homo habilis, researchers said.
Here's the question: If all this is so how do we know that the two were different species? A species is defined as a population of organisms that can interbreed and produce fertile offspring. There's no way to determine whether habilis and erectus could or could not do that. The fact that they were geographically and chronologically close and that they are classified in the same genus makes it entirely possible that they were interfertile.
One of the study's authors, however, smells trouble brewing along these lines and seeks to discourage speculation that the two may have been a single species:
Study co-author Fred Spoor, a professor of evolutionary anatomy at the University College in London [says that] the two species lived near each other, but probably didn't interact, each having its own "ecological niche," Spoor said. Homo habilis was likely more vegetarian while Homo erectus ate some meat, he said. Like chimps and apes, "they'd just avoid each other, they don't feel comfortable in each other's company," he said.
Now I have no idea how professor Spoor knows what he claims to know. I'm sure there's no record among the fossils of one group complaining of discomfort in the presence of the other. For all I and Professor Spoor know these groups intermingled both socially and sexually. Indeed, the fact that isolated fossils were found in separate locations doesn't mean that every member of those groups lived at those locations. They may well have lived together as members of the same species.
"The more we know, the more complex the story gets," he said. Scientists used to think Homo sapiens evolved from Neanderthals, but now we know that both species lived during the same time period and that we did not come from Neanderthals. Now a similar discovery applies further back in time.
The same problem as mentioned above occurs here. Our own species was contemporary with Neanderthals so how do we know that they're really two different species? The skeletal structure appears different, to be sure, but skeletal structure is irrelevant. The skeletal structure of Great Danes and Chihuahuas differs significantly but they're still the same species. The criterion for distinct species is reproductive isolation - the inability to produce fertile offspring - not skeletal structure.
Susan Anton, a New York University anthropologist and co-author of the Leakey work, said she expects anti-evolution proponents to seize on the new research, but said it would be a mistake to try to use the new work to show flaws in evolution theory.
I don't know why it would be a mistake to use this to show the flaws of evolutionary theory. Generations of students have been taught that it's a demonstrated fact that our species is linearly descended from erectus which evolved from habilis. Students since the 19th century have been shown illustrations of the progressive evolution of modern man and have been assured by their teachers that the illustrations are reasonably accurate. Now we discover that they're not accurate at all.
Meanwhile, creationists of various types, most notably the Young Earth Creationists, have for sixty years been telling us that all hominids, despite their morphological differences, are the same species. They've been insisting that the conventional assumption of a linear evolutionary progression culminating in Homo sapiens is just wrong, that the evidence for it was very weak.
The Leakey discovery confirms the creationists' argument and refutes the traditional Darwinian view. I think the creationists have a right to point that out and to remind people that the evolutionists have been wrong about this aspect of their theory for over a century.
Anton then says this:
"This is not questioning the idea at all of evolution; it is refining some of the specific points," Anton said. "This is a great example of what science does and religion doesn't do. It's a continous self-testing process."
Of course. No Darwinian would ever think that any discovery, no matter how incompatible with their theory, would ever call that theory into question, but set that aside.
What does religion have to do with this discovery? The main question raised by the article is what reason is there for assuming that H. habilis and H. erectus - or Neanderthals and H. sapiens, for that matter - are all separate and distinct species? If it turns out that they're not that fact might have dramatic philosophical and religious implications, but to suggest, as Ms Anton seems to do, that simply questioning the Darwinian paradigm of human evolution is ipso facto religious is more than a little peculiar.RLC