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EVOLUTION AND BIOLOGY

Dobzhansky was saying that the fact that evolution occurs explains the interrelatedness of the various facts of biology, and therefore makes biology make sense.

Theodosius Dobzhansky


Seen in the light of evolution, biology is, perhaps, intellectually the most satisfying and inspiring science.

Without that light, it becomes a pile of sundry facts -- some of them interesting or curious, but making no meaningful picture as a whole.

ABT 25:125-129, p. 129

Dobzhansky said, "Seen in the light of evolution, biology is perhaps intellectually the most satisfying and inspiring science. Without that light, it becomes a pile of sundry facts, some of them interesting or curious, but making no meaningful picture as a whole."

Let me give you a quick example. One area where we tend to teach "sundry facts" is in taxonomy. Right, you all know that....kingdom, phylum, class, etc.. What we're saying here is that species can be grouped into genera; genera can be grouped into families; families can be grouped into orders and so forth. The Linnaean system is really a system of nested hierarchies.



KINGDOM

PHYLUM

CLASS

ORDER

FAMILY

GENUS

SPECIES


Why is it this way instead of some other way? Why is it that families can be grouped into orders; orders can be grouped into classes; classes can be grouped into phyla? Well, most textbooks, although they are getting better, present sundry facts to to memorize. If a creature has warm blood, bears its young alive, has a single bone in the lower jaw, we put it into the group mammal. If it has jointed legs, it is an arthropod, we put it in some other group. Kids memorize all of this, but they are usually clueless as to why we can group organisms by similarities and differences of characteristics in the first place.

We should let students in on the secret. We don't classify organisms together because they look alike. Putting things together because they look alike is sorting. Ladies and gentlemen, if you start your class on evolution out with a pile of shoes or a pile of nuts and bolts and have the kids classify them, wrong. You are misleading your students. You are having them sort stuff. Shoes don't reproduce. That is the big difference between sorting and biological phenomena.

The car example. There is a whole bunch of textbooks that say "have students classify cars and show the evolutionary relationships of tail fins" or something. Wrong. This is completely backwards! It is really misleading kids on what evolution is all about. All creatures with a single bone in the lower jaw aren't grouped into mammals because they have this character, they are grouped into mammals because mammals are defined as the descendents of a creature way back when that had a single bone in the dentary. And that is why all of these creatures are mammals. Not because they have the character, but because they inherited this character from a common ancestor.

The reason all these creatures look alike is that they share a common ancestor. Evolution provides the missing bit of information that makes classification and animal diversity make sense.

nested hierarchiesOrganisms can be grouped in a hierarchical arrangement like that slide because the branching process of evolutionary change produces this nested hierarchal arrangement that you see in taxonomy. Evolution makes both the diversity of structure and the fact that you can group organisms according to structure make sense instead of a pile of "sundry facts". And this is why evolution is so important to biology and why the first Bioforum of 1997 is focusing on this topic. There are many other reasons too, but we don't have time to go into them.

Evolution is obviously very important to the California Science Framework, and if you look at any of the national programs for science education reform, the Benchmarks, the Project 2061, the National Science Education Standards, any of these will have a very prominent place for the idea of evolution. Just to take the National Science Education Standards as an example, under the Unifying Concepts and Processes, we have here "Evolution and Equilibrium" one of the very prominent ones. Unfortunately, not everyone is as enthusiastic as teachers are about teaching evolution. Which is another reason why evolution is the theme of this first Bioforum session.

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