Keynote address - Stephen Jay Gould - In the Company of Animals - Transcript

The initial vertebrates, by the way, had very small backbones--that is, the part that is not homologous--and very large gill baskets--which are the homologues, which differentiate from the rhombomeres. So the initial vertebrates in the fossil record are mostly expressing the system of segmentation that is the homologue of the insect case. It is just a fantastic story.

One last point about homology--we'll just look at the next slide--this is one of the most poignant pictures I have ever seen. This is the gravestone of Baby Fae. You may remember her story at Loma Linda University. A baboon's heart was engrafted into her, and she died. Something so touching--call it "vernacular art"--but the two hearts on a tombstone--her own, that failed, and the baboon heart that failed. Or is it her mother and father who love her?--I do not know. I do not want to make a big point about this, and I do not know whether she could have been saved any circumstances. Let us just say it was foolish in the extreme and not respectful of evolutionary principles, if the experiment was to be done at all, to use a baboon heart and not a chimpanzee heart. Baboons are 30 million years evolutionarily distant from humans. Immunological acceptance or rejection is a question of overall genetic similarity, which is homology. Chimpanzees are six to eight million years different. If you look at Dr. Bailey's justification for why he did the procedure, he justified it only in functional terms. Well, a baboon heart is about the right size; chimpanzee hearts are hard to get. But then we come to the key point: Dr. Bailey is a Seventh Day Adventist--he does not believe in evolution. Sometimes, if you do not acknowledge what it is all about, you can make some tragic errors. I will leave it at that.

Although homology is a legitimate theme, there are many fallacies based on false usages of evolution. The one I have written about most in my own career is gradualism, progressionism, and continuity theories in general. Not everything is homology. Consider the chimp-language debate--I do not want to insert myself in something that I do not know a great deal about, but I think everyone would agree that many errors were made in assuming that there could be a kind of strict continuity between basically gestural systems of organisms that are close to our ancestry and our own language faculty, which is uniquely human. Many people even misread Chomsky as a quasicreationist, because he says there is no continuity. He does not mean that God put it in there. He means that what we call the language organ may have been co-opted from some other mental function. Certainly, evolution does not always work by adaptive gradualistic continuity, though this is one of its modes.

And then we have other fallacies, the main one being the supremacist, or progressionist fallacy--the paradox of seeing animals as both lesser than us, but also defined by us--or even by our arbitrary words in the examples I gave at the beginning.