 |
Humans are natural taxonomists. Whether a "lumper" or a "splitter" a person will invariably classify the things around them into logical groups and then refer to these groups to discuss a large range of objects rather than one, specifically. Scientists go through the same processes when classifying organisms, but whereas common (of folk) classifications spring from human perspectives, formal taxonomy is (or, at least, strives to be) an objective assessment of an organism's actual relationships. Folk classifications are eminently serviceable to their own purposes, and often very complex, but the classification system used by modern biologists (cladistic taxonomy) is based upon different criteria. To construct a cladogram, a picture of "life's golden tree", one must be able to separate true relationships between organisms from mere superficial similarities. Exactly how one goes about doing that requires some background and is the subject of this introductory chapter.
By the 18th and 19th centuries, zoologists were beginning to draw conclusions (or at least ask better questions) about life's origins. As European scholars set out to systematically catalogue natural world, they began to notice patterns. Elephants in Africa bore a striking resemblance to those in India, but kangaroos in Australia looked like nothing else on Earth. Just as humans had bred different kinds of dogs, there was clearly some process was at work, making different breeds of everything else. For most of history, scholars, if they gave the matter any thought, followed Plato in assuming that modern breeds of organisms were corrupted descendants of perfect archetypes. Later biologists (most notably Jean de Monet, the Chevalier de Lamarck) theorized that an organism's environment communicated changes that it could pass on to the next generation. We are all familiar with the example of the giraffes stretching their necks and the smith's strong right arm being passed to his son, but these early evolutionary hypotheses do have some merit. The Platonic ideal of corrupted archytypes (if one strips away the moral connotations) are strikingly similar to Darwinian theory (which I will get to in a minute) and Lamarckian evolution, long considered completely wrong-headed, has now been revealed as a valid method of biological change, at least in some cases. Modern evolutionary theory, however, is most emphatically not Lamarckian or Platonic, but Darwinian.
Etc.
Hey, I can't finish this page until I can remake the cladograms, and I can't do it until I've revised the taxon
pages. Have patience and check the old page.
|
|
|
