Category: Modern Science

99%? 95%? 87%? 70%? How Similar is the Human Genome to the Chimpanzee Genome?

I recently got an E-MAIL from a student who heard a “university professor” say that the human and chimpanzee DNA are 99% similar. She asked whether or not the professor was correct and, if not, how similar is human DNA to chimpanzee DNA?

Well, the answer to her first question is quite easy. The professor was horribly wrong. The nonsensical idea that human and chimp DNA are 99% similar comes from misinterpreting a 1975 paper by Mary-Claire King and A. C. Wilson. 1 This groundbreaking (for its time) article compared several proteins in chimpanzees to their equivalent proteins in humans.

In case you don’t know, proteins are complex molecules that are composed of many smaller molecules (called amino acids) linked together. The primary structure of a protein is simply the order in which its amino acids link up. King and Wilson showed that in many, many proteins, the difference in the primary structures of chimpanzee and human proteins was about 1%. Since DNA determines the order of amino acids in each protein an organism makes for itself, they made the reasonable inference that for the portions of DNA that code for those proteins humans and chimpanzees are 99% similar.

However, the genes that code for these proteins make up a tiny, tiny fraction of the human or chimp genome, and only SOME of those proteins were studied. Thus, the idea that one can extend that number to the entire genome and say that human and chimp DNA are 99% similar is just absurd.

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Dr. Coyne Won’t Debate

The AP article that tried unsuccessfully to discredit the biology text I co-authored as well as the biology text published by Bob Jones University Press is still causing a bit of a stir. This morning, a radio talk show host name Adam McManus sent an invitation to both me and Prof. Jerry Coyne to be on his show to debate the merits of the article. Of course, I agreed right away, since I have no fear of debating anyone on the creation/evolution issue. After all, the facts are on my side. Why wouldn’t I want to debate them?

Well, Dr. Coyne refused to be on the program with me. Mr. McManus then wrote him back trying to convince him that he should do the debate. Mr. McManus even implied that Dr. Coyne seemed afraid to debate. Dr. Coyne still refused, claiming that it wasn’t fear. He said he would be glad to appear by himself, but not with me, because that would give me an air of legitimacy that he does not want to give me.

I find that attitude very interesting. I am not sure why debating someone gives him or her an air of legitimacy. In fact, I think not debating someone gives him or her an air of legitimacy. After all, if you are willing to publicly debate someone, it generally means you think you have the ability to show that the person’s position is wrong. If you refuse to debate someone, it looks more like you are afraid of that person’s arguments. To me, that makes the person’s case look more legitimate and, in fact, superior to yours.

So….even though it is not going to be nearly as interesting, I will be on by myself on March 24th at 5:00 Central time. Dr. Coyne might be on after me or at some other time. I don’t know. The station is AM 630, KSLR.

What Can a Dead Fish Tell You About the Nature of Science?

I am currently doing an Alaskan tour of six cities in seven days, working with educators in a state-wide, publicly-funded charter school system. Even though it is cold, it is a lot of fun. Alaska is beautiful, and the charter school system is excellent. It is great to see quality education occurring in such a novel way.

Because airplanes are the main way one gets from city to city in Alaska, I have been spending a lot of time sitting in airports, on tarmacs, and occasionally on an airplane that is actually flying. As a result, I have been doing a lot of reading. I came across an interesting article in Science Science News today1, and I think it is a great illustration of something I stress in most of my science books.

For several years now, scientists have been using functional magnetic resonance imaging (fMRI) to observe functioning brains. The main technique involves using a magnetic resonance imaging machine to look for small changes that occur within the blood vessels of a person’s brain. The very reasonable argument proposed is that the more active a neuron is, the more blood it needs. Thus, if the fMRI sees an increase in blood flow to a particular region of the brain, the neurons in that region must be more active. So…a subject is stimulated in some way, and the fMRI looks for increases in blood flow. Any region of the brain that “lights up” must be the region that is responsible for either processing whatever stimulus was provided or producing a response to it.

Several hundred papers have been published discussing the results of all manner of fMRI experiments, and they have made all sorts of definitive conclusions regarding what regions of the brain are responsible for processing various stimuli or producing various responses to those stimuli. Well, Craig Bennett wanted to see how reliable fMRI experiments are, so he decided to do a very simple baseline test. He used fMRI to study the way a dead fish’s brain responds to stimuli.

The results were quite interesting.

Continue reading “What Can a Dead Fish Tell You About the Nature of Science?”