Dear Straight Dope:
I am not a believer in evolution, but I ran across this expression, and wondered why it isn't used in arguments against evolution. The expression is: If man evolved from monkeys and apes, why do we still have monkeys and apes?
SDStaff DavidB replies:
Why isn’t this argument used against evolution? Well, it is — it’s just used incorrectly. Let’s start with a quote from the recently re-released publication, Science and Creationism: A View from the National Academy of Sciences (Second Edition). In the section on “Human Evolution,” the publication notes, “today there is no significant scientific doubt about the close evolutionary relationships among all primates, including humans.”
Evolution doesn’t work as a simple find-and-replace function. Have you ever seen the evolutionary “tree” diagrams in a science book? Those trees show how different species branch off and go in different evolutionary directions. That doesn’t necessarily mean everything else dies. As the National Academy of Sciences document notes, archaeological finds “reveal a well-branched tree, parts of which trace a general evolutionary sequence leading from ape-like forms to modern humans.”
The NAS publication actually answers your question directly in its Appendix of Frequently Asked Questions. It says:
“Humans did not evolve from modern apes, but humans and modern apes shared a common ancestor, a species that no longer exists. Because we share a recent common ancestor with chimpanzees and gorillas, we have many anatomical, genetic, biochemical, and even behavioral similarities with these African great apes. We are less similar to the Asian apes orangutans and gibbons and even less similar to monkeys, because we share common ancestors with these groups in the more distant past.
“Evolution is a branching or splitting process in which populations split off from one another and gradually become different. As the two groups become isolated from each other, they stop sharing genes, and eventually genetic differences increase until members of the groups can no longer interbreed. At this point, they have become separate species. Through time, these two species might give rise to new species, and so on through millennia.”
In other words, the “ape-like” animals that eventually gave rise to humans split up into several branches, all of which evolved in different directions. Some of those lines became become extinct; others survived. One of the surviving groups includes you and me (and in theory P.E. teachers, although one wonders). Other survivors include the various species of monkeys and apes we find today.
So, John, I’ve convinced you, right? Attaboy — always nice to have another ally in the fight against ignorance. Incidentally, you can find the NAS publication on the web at http://books.nap.edu/html/creationism/. Lots of good info in there!
SDStaff DavidB, Straight Dope Science Advisory Board
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