Some citations from Christian De Duve, Vital Dust 1995. Chapter 13, The Universality of Life
In the introduction to this book, I argued on theoretical grounds – remember the thirteen spades – that the ermergance of life must have involved a very large number of steps, most of which had a high probability of occuring under the prevailing conditions. But left open the possibility that there might be more than one pathway compatible with this exigency. My conclusion, after a consideration of the underlying chemistry, is that, given the opportunity, the development of life is very to take the course it actually took, at least in all essential steps.
The figure of about one million “habitable” planets per galaxy is considered not unreasonable. Even if this value were overestimated by several orders of magnitude, it would still add up to trillions of potential cradles for life. If my reading of the evidence is correct, this means that trillions of planets exist that have borne, bear or will bear life. The universe is awash with life.
But the term “artificial life”, applied by analogy with “artificial intelligence”, could be misleading. Life is a chemical process. If it is ever to be created artificially, it will be by a chemist, not by a computer.
The chapter The Future of Life (p. 271)
“We have reached a crucial state in the history of life. The face of the Earth has changed dramatically in the last few thousand years, a mere instant in evolution time, and it is changing ever faster. What would have taken one thousands generations in the past may now happen in a single generation. Biological evolution is on a runaway course toward severe instability.
In a way, our time recalls one of those major breaks in evolution signaled by massive extinctions. But there is a difference. The cause of instability is not the impact of a large asteroid or some other uncontrollable event. The perturbation is from life itself acting through a species of its own creation, an immensely successful species filling every corner of the planet with continually growing throngs, increasingly subjugating and exploiting the world. For the first time, also, in the history of life, natural selection has been replaced, be it only partly, by willful intervention on the part of a member of the bioshperic community. The facts are before us clear and unmistakable. Everybody can read the message and draw the obvious conclusions.”
Chapter 26, Brain, p. 240:
The human brain has completed all the neurons it will ever make some five month before birth. Contrary to what happens to other cell types, multiplication of neurons ceases after that. Henceforth, neurons only die, starting in utero, to the tune of hundreds of thousands per day. I have lost several billion neurons since I was born. Between starting and finishing this sentence, I have lost about one hundred more. The thought is unsettling, but I take comfort in assurance from my neurobiologist friends who tell me that many brain connections are superfluous and redundant and that, even though I cannot replace my neurons, I can still rewire some connections if I keep sufficiently busy.
about Gaia, p. 220-221.
She was the Mother Earth goddes of the ancient Greeks. Long forgotten, except in such words as geology, geography, and geometry, she has recently been revived by James Lovelock, a distinguished English scientist, an F.R.S. (Fellow of the Royal Society), the most coveted set of initials to follow a British scientist’s name. A physisist by training, Lovelock is a successful inventor of scientific instruments who enjoys a comfortable income from the patents he earned when he was young. He now lives as the proverbial “gentleman of independent means” in a converted eighteenth-century water mill near the border between Devon and Cornwall, the most sourthwestly English counties. Coombe Mill (Experimental Station) is both Lovelock’s home and the computer-crammed laboratory in which he simulates the whims and vagaries of Gaia.
What distinguishes Gaia from other global concepts is homeostasis, self-regulation. In Gaia, life and Earth do not simply interact haphazardly. They do so in a manner that tends to correct the imbalances they inflict on each other.
According to the Gaia theory, the Earth is a living organism that automatically regulates its environment so as to make it optimal for life.