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Thursday, March 01, 2012

If humans descended from apes, why are there still apes?

"If humans descended from apes, why are there still apes?"

I have seen this question, or one much like it, on Facebook, a couple of times in the last few days. I doubt that the person posting that really expects an answer, of any kind. It's (I suppose) a rhetorical flourish. However, here's an answer.

No serious biologist believes that humans descended from chimpanzees, bonobos, gorillas or orangutans. Most scientists believe that these great apes, and humans, had a common ancestor. It is possible that they are wrong, and that humans were specially created by God. I'll not consider that any further in this post, because the statement I'm responding to is really saying this: "OK, Mr. Scientist. You believe that humans descended from apes. How can that be possible, since apes are still around?"

I'll respond with this question: "If cell phones descended from land line phones, how come there are still land line phones?" Granted, of course, that phones don't descend from anything, but are manufactured, and that all analogies are less than perfect, it still is relevant to the original question.

In the first place, we can see the "common ancestor" again. Both cell phones, and land line phones, have evolved since the first cell phones were introduced. (See here for the Wikipedia article on the history of mobile phones, which were first introduced in the 1940s) The common ancestor is not around any more.

Second, different types of phones are in existence because there is, or has been, a market for them. Land lines are usually cheaper than cell phone service. Most people can't use their cell phones for connecting their computers to the Internet, and, for example, downloading large application programs. Our land line works well for that. On the other hand, there are many things you can do with a cell phone, even a non-smart phone, that are impossible with a land line. For example, if your land line stops working, you can use your cell phone to inform your land line carrier of the problem.

What does this have to do with apes and humans? Biologists believe that, for a new species to arise, it must occupy an ecological niche. What is an ecological niche? It's where the species lives, and how it obtains its energy. For animals, where it lives, and what it eats. Presumably primitive humans, either created specially by God, or coming from some ancestral form, were able to take advantage of ways of living that other creatures were not, most likely by being able to construct or occupy dwellings of various kinds, and by being able to cultivate crops and to domesticate animals. So they survived as a species. But there are other ecological niches, still occupied by the great apes, that humans don't fill, or don't fill very well, such as living on less than 200 species of plants, on the cold and cloudy slopes of mountains in Africa, as the Mountain Gorilla does. As long as there are available ecological niches, which humans are poorly equipped to occupy, we can expect the great apes to continue to exist. (Unless we hunt them to extinction.) This is true whether or not we share a common ancestor with them. There are good reasons for the continued existence of humans, and of great apes. Similarly, land lines and cell phones both exist because there are good reasons for their existence -- there are niches for both of them. In both cases, the arrival of a new entity did not mean that an older one would cease to exist.

Another response is this. "If dogs descended from wolves, why are there still wolves?" (As far as I know, all biologists, including those who believe that humans were specially created on an earth which is only a few thousand years old, believe that dogs descended from wolves.) The answer is similar to the telephone story. Dogs exist because there is an ecological niche, however artificial, available to them. So do wolves, in a different ecological niche. Clearly dogs have evolved into many different breeds or races, mostly under the direction of dog breeders. But dogs which seem to be much like wolves still exist. Most likely, wolves, themselves, have changed in small ways over the last several thousand years, so that they, also, are not identical with the wolf-dog common ancestor, or ancestors. But there are still wolves, and there are still dog breeds which most likely gave rise to newer breeds. The arrival of dogs didn't mean that wolves would immediately go extinct.

I hope that this answers the question. Thanks for reading.

3 comments:

atlibertytosay said...

I'm not one to post or reply such a comment on facebook … but I've seen the comments as well.

I appreciate your scientific answer. I think the reasoning behind the post is to solicit your more "Godly retort" though.

I do not believe we had a common ancestor of any type. Of course when I say I believe, I move away from the scientific explanation. That doesn't always mean that I haven't used my understanding of science to come to that conclusion.

I've done a lot of study on this because I know that this topic will come up at some point in my life when I do any sort of apologetics for Creationism or Intelligent Design.

From http://www.ornl.gov/sci/techresources/Human_Genome/faq/compgen.shtml ...

The often-quoted statement that we share over 98% of our genes with apes (chimpanzees, gorillas, and orangutans) actually should be put another way. That is, there is more than 95% to 98% similarity between related genes in humans and apes in general. (Just as in the mouse, quite a few genes probably are not common to humans and apes, and these may influence uniquely human or ape traits.) Similarities between mouse and human genes range from about 70% to 90%, with an average of 85% similarity but a lot of variation from gene to gene (e.g., some mouse and human gene products are almost identical, while others are nearly unrecognizable as close relatives). Some nucleotide changes are “neutral” and do not yield a significantly altered protein. Others, but probably only a relatively small percentage, would introduce changes that could substantially alter what the protein does.

Human bodies contain roughly the same amount of water as a melon ~ should we draw any sort of comparison?

I find that drawing conclusions by comparison and thereby coming to any more than a theory is faulty logic.

Anyone considering the topic of evolution should always maintain that it is theory … albeit a very well documented and observable one. But being so doesn't make it any more or any less connected to God and his plan for creation … nor does being connected to God's creation imply religious bias.

Martin LaBar said...

Thanks, atlibertytosay.

As I am sure you are aware, DNA similarity and water content are quite different -- DNA is a complex molecule, and, until recently, made only in living cells, and it carries the information specifying what cells do from one cell (or generation) to another. Water molecules are interchangeable, and, though important, they don't determine our characteristics.

My purpose in writing was, I guess, to vent my frustration with what I see as a stupid comment, without attacking the people who posted it.

One of the problems with discussions in this area is that we don't often define "evolution," and we also don't define "theory," in these discussions.

atlibertytosay said...

Agreed.