|Athro, Limited Biology Evolution Rhetoric
|Rhetoric in evolution
The scientific observation of evolution in the natural world is often carried back into human society and laden with human political agendas. Evolution has most often been associated with progress - that is with a view of the world as progressive, and humans (particularly white European males) being at the top of the tree. The phrase, at the top of the tree, can be literal:
The tree of human evolution
according to Ernst Haeckel, 1891
This is an evolutionary tree drawn in the late 1800s. The great German evolutionary biologist Ernst Haeckel used this tree to illustrate his view of the evolution of life from bacteria to humans.
At the top of Haeckel's tree are Menschen - men, and Haeckel meant white European males.
In middle of his tree are reptiles, and below them amphibians.
At the base of his tree are single celled amoebas, and "monera" - Haeckel's name for the bacteria.
Haeckel's picture of evolution was a picture of linear progress from bacteria to humans. Indeed, he defines four explicit stages of progress (on the right side of the picture): Protozoa, Invertebrates, Vertebrates, Mammals.
Haeckel's tree redrawn to show just
This picture shows Haeckel's view of the relationships among what he called the Anthropoid apes (The current view of these relationships is rather different, with the bonobo and chimpanzee as closest to humans). Haeckel's picture can be redrawn (and the names translated) to show just his opinion of the relationships. This lets us see that Haeckel thought that chimps and gorillas were closely related, and that orangutans and gibbons were closely related. But it also shows that that he didn't know who was most closely related to humans. Compare Haeckel's picture with our redrawn view of the relationships. Haeckel's evolutionary tree shows two things 1) his opinion of relationships among various organisms, and 2) progress.
Haeckel's tree explicitly embeds the notion of progress - things nearer the top are 'more evolved' or 'higher' and things nearer the bottom are 'less evolved' or 'lower'. This is Bunk. Evolution is adaptation to local circumstances. There is no general trend of gradual continuous progress in evolution.
And so, if you wish to ask the question of the ages - why do humans exist? - a major part of the answer, touching those aspects of the issue that science can treat at all, must be: because Pikaia survived the Burgess decimation. This response does not cite a single law of nature; it embodies no statement about predictable evolutionary pathways, no calculation of probabilities based upon general rules of anatomy or ecology. The survival of Pikaia was a contingency of "just history." I do not think that any "higher" answer can be given, and I cannot imagine that any resolution could be more fascinating. We are the offspring of history, and must establish our own paths in this most diverse and interesting of conceivable universes - one indifferent to our suffering, and therefore offering us maximal freedom to thrive, or to fail, in our own chosen way.