It’s been ages since I added anything to this blog – I guess it’s about time!
Death and Taxus. Constants of the universe. Taxus is the scientific name of the trees known as yew, with needle-like leaves and single seeds surrounded with a red, berry-like tissue. It’s an old botany joke (and it’ll make a great chapter title).
Cy Finnegan passed away almost a year ago. He had a good run and almost made it to 90. I think about him a lot (it would be good if he’s in some fine, unknowable, Catholic heaven-place) and hope I can do a decent job of distilling the ideas of Cy and Jack. Many of these thoughts and speculations Cy and Jack distilled from others (always giving them credit, of course) – no single person or small group has all the good ideas – it’s the strength of collaboration. But too few people think or talk about these ideas and I can’t help myself.
I don’t know about yew trees, but death, at least for us big multicellular critters, seems to be an unavoidable consequence of life. Development of an individual from single-celled zygote to old adult is an evolutionary phenomenon. The only way membership in a species can be expressed, complete with characteristics tying an individual to relatives both close and distant, is through development, making ontogeny an aspect of evolution. As a zygote, energy flows into us and we race away from simplicity to remarkable (but not miraculous) complexity. Most of us enjoy what seems like invincible youth, and then we age (even if in our heads we’re all still sweet, young things). Whatever the specific cause may be, eventually we all wear out and go to equilibrium. What’s more, the life span of organisms falls within a species-specific range. Some insects live for a few weeks. Annual plants live for a year. Bristlecone pines can live for thousands of years. These days many humans make it through their 80s, maybe even to 100, but not far beyond that. No matter what we do, humans just don’t live to be 150 (at least not physically, and we don’t have much evidence for what may happen beyond that). The idea that life span is tied to species membership, and so to evolution, isn’t something biologists talk about very much (except for hucksters or fools who consider death itself a disease), but it’s worth considering.
And what about extinction – the death of a species? All of our theories invoke extrinsic causes – meteors, ice ages, killer-hot climates and the nasty behavior of humans. No question, humans have caused the extinction of many of our fellow inhabitants of the planet – there’s plenty of evidence. But large numbers of species went extinct before we were around to mess things up. Did meteors cause all of those cool dinosaurs to go down for the count? What about trilobites? Could it be that species, like individuals, have life spans? I’m just suggesting the possibility.
Life is hierarchical – not in the sense of some sort of top-down command structure, but in the sense of nested sets of organization – cells specialized and organized into tissues and organs and finally whole self-contained critters. Farther up the hierarchy the critters are organized into species and related groups of species. Why would this be? Does natural selection offer a rational, underlying causality? I say no. It would be far more rational to point to the 2nd law of thermodynamics as the law of nature fundamentally responsible for the occurrence, complexity and diversity of life – the 2nd law a la Prigogine – as he suggested, this presumed regularity of the universe behaves differently in systems open to the flow of energy, causing self-organized and self-propagating systems to arise, even if they don’t last forever. The 2nd law may provide an underlying causal explanation for death as well. Though new individuals arise continually, sooner or later we all go to thermodynamic equilibrium. We get old and at some point are no longer able to process matter / energy, and keep our distance from equilibrium. We go down for the count and our tidbits flow back into the greater system to be used by newly-developing living systems. Perhaps the same thing happens on a larger scale, to groups of individuals connected to each other not by physical ties, but by their species membership, by their close sharing of evolutionary history. I don’t know just how this would work, but I’m putting it out there. C’mon brave evolutionary biologists! Let’s expand the the conversation beyond the 150-year-old theory of natural selection. It appears to be alive, but only because it’s been so well embalmed. Natural selection just doesn’t provide a satisfying, coherent, non-magical explanation for anything (it pretends to justify the one big fish eating all the little fish, which doesn’t happen except in critically damaged systems – social Darwinism is its logical conclusion, though true believers deny this without offering counter-arguments) so shake free of it, if only for a moment, and consider more rational, powerful theories.