On The Cosmic Calendar, A Date To Remember

Carl Sagan, describing his twelve-month capsule of the history of the cosmos, summarized its lesson this way: “The world is very old, and human beings are very young.”  But a neglected date on the calendar points to a different conclusion about organic life itself.

Sagan included “The Cosmic Calendar” in The Dragons of Eden in 1977. The first voyage to Mars had lifted off two years earlier. NASA, with Sagan’s help, began listening for and sending messages to other intelligent beings who might have been out there. Sagan, while asking readers to appreciate our amazing intelligence, at the same time believed that we were not the only creatures in the universe who were so endowed. The Cosmic Calendar helped him show that because it took eons to produce human civilization, the eons might have led to similar results elsewhere.

On the Calendar, one month represents about 1.1 billion years, one day equals 38 million years, and in one brief second, 438 years fly by. The Big Bang, 13.8 billion years ago, explodes on January 1. The Milky Way takes shape around March 11 (dates are from the Wikipedia version) and our Sun first shines on September 2, with planets soon after. The first living cells stir on September 21. October features photosynthesis, the gradual oxygenation of the atmosphere, and the persistence of simple bacteria and their cousins. In November, those single cells develop nuclei, complexity, and greater energy, leading to the first multi-celled organisms in early December. From then on, the variety of life emerges swiftly: fish and land plants in mid-month, dinosaurs at Christmas, then birds and flowers, and humans in the last hours of New Year’s Eve.

 

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(3.bp.blogspot.com)

But this late appearance of humans may distract us from another date. September 21 marks the date for the beginning of organic life itself, only a few “short” weeks (about 700 million years) after the formation of the planets. From that date on—for more than a quarter of the duration of the universe—life has existed on Earth. While humans may be newcomers, living things are not. Our chain of ancestors are long-time participants, old-timers in the cosmos. We humans are fully part of the long cosmic process, not just because our atoms are star-stuff but because our cells have their “months” of cosmic history.

What is new in us, with our nearly-New-Year’s intelligence, is that we are aware of all this. But our living spark is nearly as old as planets.

Shall we celebrate September 21 each year as the “Birthday of Life”?

New Thinking About the Origin of Life (1): Purposes and Selves

How does a living thing differ from a lifeless one? And how might those living characteristics have emerged from the lifeless matter that preceded them?

Jeremy Sherman’s new book, Neither Ghost Nor Machine: The Emergence and Nature of Selves, discusses recent thinking on these questions, especially the work of neuroanthropologist Terrence Deacon. In this post and the next, I’ll summarize highlights.

Sherman is emphatic about one particular difference between living and non-living things: all living things have purpose, non-living entities do not. Purpose here has little to do with 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. For example, 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 all their parts serve functions and yet it may feel strange at first to identify purpose itself as a defining feature of all organisms.

campfire (shutterstock.com)

shutterstock.com

Non-living stuff, on the other hand, has no such purpose or aim or sustaining function. A fire in the fireplace burns and gives off heat and carbon and other gasses, after which 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).

New selves? Sherman, following Deacon, refers to organisms as selves. Applying self to an organism calls attention to the ways that even a bacterium as well as a human works to find food, defend its self, repair its self, and make more selves. Inanimate things aren’t 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.

A related difference between selves and inanimate things is that with selves, we can say that something—fuel, information, a change in temperature—is good or bad or useful or significant for it. But for inanimate things, as Sherman puts it, “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 fails to explain the first appearance of all those 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, the question: what kinds of inanimate chemical reactions might have come together as stepping-stones towards purposeful, self-regenerative selves? Until now, that question has been explored in terms of possible ingredients. Chemical stews, viruses, RNA molecules, an iron-and-sulfur world have been among the candidates for starting points. But Terrence Deacon has asked instead what kinds of reactions, regardless of their ingredients, could sustain themselves long enough to postpone the terminal fizzle?

His answer, in the abstract, is that you need not one but two reactions, each of which constrains the other before it burns out. I’ll explain in my next post.