How, specifically, is a living thing different from lifeless chemistry? Once we can answer that question, we can ask the next one: How did the first emerge from the second?
Jeremy Sherman’s new book, Neither Ghost Nor Machine: The Emergence and Nature of Selves explains recent thinking on these questions, especially the work of neuroscientist Terrence Deacon. In this post and the next, I’ll summarize highlights of the book.
Sherman emphasizes this difference between living and non-living things: living things have purpose and non-living entities do not. Purpose here has little to do with what we mean when we talk about a person’s “sense of purpose” and it has nothing to do with divine intention. It refers instead to biological processes aimed at maintaining the state of being alive. The heart’s purpose—its function—is to pump blood. The purpose of a leaf is to produce food for the plant. We take for granted that bodies and their parts serve functions and yet it feels strange at first to identify purpose itself as a distinguishing feature of all organisms.
Non-living stuff has no such purpose or aim or sustaining function. A fire in the fireplace burns and gives off heat and carbon and other gasses and then the fire, without more fuel, goes out. Sherman writes, “Most chemical reactions yield a proliferation of molecular products” but such reactions soon peter out. The reactions in living things, on the other hand, don’t fizzle out so easily. Through their biochemistry, living things “are self-regenerative in two senses: they maintain their own existence, and they produce new selves” (9).
Produce new selves? Sherman (like many biologists) refers to organisms as selves. Like purpose, applying self to an organism calls attention to the ways that even a bacterium, like a human, works to find food, defend its-self, repair its-self, and make more selves. Inanimate things don’t act as selves. Left alone long enough, anything inanimate will become disorganized and break down. An ice cube left on a counter will melt and then evaporate, its molecules finally dispersing into the air. And with selves, we can say that something—fuel, information, lower temperature—is good or bad or useful or significant for it. In contrast, as Sherman writes, “Nothing is ever functional, significant, or adaptive for sodium chloride, snowflakes, mountains, fried chicken, or even computers” (25).
But what about natural selection? Didn’t Darwin’s work explain how living things evolve? Yes, but natural selection doesn’t explain the first appearance of the selves that do the evolving. “To claim that natural selection explains purpose is like claiming that erosion explains mountains. Erosion…explains how mountains are passively sculpted, but not what’s sculpted. Likewise, natural selection explains how populations of selves are passively sculpted…[as] some lineages produce more offspring than others, but not how selves arise in the first place.” (9).
So, here’s the mystery: what kinds of inanimate chemical reactions might have come together as stepping-stones towards purposeful, self-regenerative selves? I’ll summarize Sherman’s answers in my next post.