Why we walk upright

I respect David Limbaught's political viewpoint, and almost always enjoy his articles. However, I was disturbed by this post, in which he gave a forum to a letter writer who argues that it is impossible that man could be descended from walking simians. I will be the first to acknowledge how little I know about science, biology, etc., but there was a manifest logical fallacy in the letter that I feel needs to be addressed. First, here is the meat of the letter:

There is a common misconception concerning evolution which continues to be perpetuated. For example, recently ( in November of '04 ) articles appeared in major newspapers saying researchers have claimed that running may have contributed to the evolution of man. The simple fact is that physical traits and characteristics are determined and passed on by genes - not by running or any other form of exercise. Any exercises that are performed do not affect the genes. Traits or characteristics which are acquired from the environment simply cannot be passed on to offspring ( i.e. a woman who loses her finger will not cause her baby to be born with a missing finger; changing the color or texture of your hair will not affect the hair color or texture of your descendants, and etc. ). Thus, even if an ape ever did learn to walk and run upright it still would not be able to pass on this trait to its offspring. Only changes that occur in the genes of reproductive cells ( i.e. sperm and egg ) can be passed on to offspring. That is a simple fact of biology. Furthermore, there are genetic limits to biological change and variation in nature. All biological variations, whether they are beneficial to survival or not ( including biological variations from mutations ), are possible only within the genetic potential and limits of a biological kind such as the varieties among dogs, cats, horses, cows, etc., but variations across biological kinds such as humans evolving from ape-like creatures and apes, in turn, evolving from dog-like creatures and so on, as Darwinian evolutionary theory teaches, are not possible unless nature can perform genetic engineering. Yes, natural selection does occur in nature, but natural selection is only capable of selecting from biological variations which are possible. Natural selection itself is not capable of increasing the genetic potential in species and neither are mutations for that matter. Therefore, it is much more logical to believe that the genetic and biological similarities between species are due to a common Designer rather than to a common evolutionary ancestry.

The author of this letter, Babu G. Ranganathan ( B.A. Theology/Biology), is correct that behaviors are not going to be passed from generation to generation, and cannot be responsible for changing a species. However, he is incorrect to conclude that all behaviors are just that -- behaviors, unrelated to biological factors. One can easily envision an ape-like animal with a mutant gene that affects its hips, so that it is easier for the animal to stand upright than to travel on all fours. (I have a childhood memory of a photo from the 1950s of a poodle strolling upright along New York streets, the victim (beneficiary?) of a genetic hip problem that made it more comfortable walking on two legs.) Now, imagine that some predator attacks a group of simians that includes this upright ape. All of them run for it -- and, lo, the upright ape runs fastest. Several of the animals are killed, but not our upright ape. He goes on to father three children, two of whom inherit his genetic anomaly. Another predator scenario, and this time both of his progeny, by running upright, escape. They, too, live to breed, unlike some of their less successful comrades on four legs. And so it goes on, generation after generation, with the upright apes repeatedly proving to be more successful in eluding prey and, therefore, being more successful in passing on this "mutant" gene. The thing is, though, after multiple generations, that gene is no longer mutant -- it's the dominant gene that results in upright apes, capable of consistently outrunning predators. And if you doubt this scenario, just think about the fact that more and more bacteria are antibiotic resistant. This occurs because those bacteria that have genetic mutations that enable them to resist the "predator" (here, bacteria) are the ones who get the chance to multiply, spreading their genetic mutation until it becomes normative. I remain open to all possibilities regarding the creation of our world, provided that the arguments are logical. I do not think Mr. Ranganathan's refutation of evolution is sound here, and believe it deserves to be discounted until (if possible) a better one comes along. UPDATE: Not quite on point, but certain apropos, is this NY Times Op-Ed in which a proponent of intelligent design explains the theory. (And I must say, I'm favorably impressed that the NY Times gave him a platform for his opinions.)