The Atheist's Guide to Reality_ Enjoying Life Without Illusions - Alex Rosenberg [37]
It’s well known that every major change and many minor ones in the environment condemn hitherto fit creatures to death and their lineages to extinction. As environments change, yesterday’s adaptation becomes tomorrow’s maladaptation. In fact, it looks like three different cataclysmic events have repeatedly killed off most of the life-forms on Earth. The dinosaur extinction 65 million years ago, owing to an asteroid collision on the Yucatán peninsula, is well established. There are no dinosaur bones in any of the younger layers of stone around the world, but there is a layer of iridium—an element found in much higher concentrations in asteroids than on Earth—spread evenly around vast parts of Earth centered on the Yucatán in layers of rock 65 million years old. In that layer, the iridium is 1,000 times more concentrated than elsewhere above or below it in Earth’s crust. At a stroke, or at least over only a few years, all the vast numbers of dinosaur species, which had been adapting to their environment beautifully for 225 million years, just disappeared. That’s what made the world safe for the little shrewlike mammals from which we are descended. The fossil record reveals an even bigger extinction event on Earth 500 million years ago and an even more massive extinction after that, 225 million years ago: the Permian-Triassic extinction, in which three-fourths of all ocean-living genera and almost 100 percent of ocean-dwelling species along with 75 percent of land species became extinct. This is order-destroying waste on an enormous scale.
Long before all this, it was the buildup of oxygen in the oceans and in the atmosphere that killed off almost everything on Earth! Buildup of oxygen? How could oxygen be a poison? Remember, yesterday’s adaptation can be today’s maladaptation. Life started in the oceans with anaerobic bacteria—bacteria that don’t need oxygen. In fact, they produce oxygen as a waste product the way we produce carbon dioxide. Just as the plants clean up our mess by converting carbon dioxide to oxygen and water, the environment cleaned up all that oxygen pollution by molecular action, binding the oxygen to iron and other metals. At some point, the amount of oxygen waste produced by the anaerobic creatures exceeded the absorption capacity of the environment. As a result, they all began to be poisoned by the increasing levels of oxygen around them. Around 2.4 billion years ago, these bacteria were almost completely wiped out, making enough space for the aerobic bacteria, the ones that live on oxygen and produce carbon dioxide as waste. We evolved from these bacteria.
Can any other process produce entropy as fast and on such a scale as natural selection? Just try to think of a better way of wasting energy than this: build a lot of complicated devices out of simpler things and then destroy all of them except the few you need to build more such devices. Leaving everything alone, not building anything, won’t increase entropy nearly as fast. Building very stable things, like diamond crystals, will really slow it down, but building adaptations will use up prodigious amounts of energy. Adaptations are complicated devices; they don’t fall apart spontaneously, and they repair themselves when they break down. They persistently get more complicated and so use even more energy to build and maintain themselves. Any long-term increase in the number of adapted devices without increased energy consumption would make a mockery of the second law. If such devices ever appear, besides being rare, they had better not persist and multiply, unless by doing so they inevitably generate more energy wastage than there would have been without them. This is the very process Darwin envisioned: in Tennyson’s words, “nature red in tooth and claw.”
Kelvin had the wrong end of the stick when he argued that there has not been enough time for natural selection to produce the adaptation,