” Natural selection,” Arby said.
“Yes, that was Darwin’s explanation. The environment exerts pressure which favors certain animals, and they breed more often in subsequent generations, and that’s how evolution occurs. But as many people realized, natural selection isn’t really an explanation. It’s just a definition: if an animal succeeds, it must have been selected for. But what in the animal is favored? And how does natural selection actually operate? Darwin had no idea. And neither did anybody else for another fifty years.”
“But it’s genes,” Kelly said.
“Okay,” Malcolm said. “Fine. We come to the twentieth century. Mendel’s work with plants is rediscovered. Fischer and Wright do population studies. Pretty soon we know genes control heredity-whatever genes are. Remember, through the first half of the century, all during World War I and World War II, nobody had any idea what a gene was. After Watson and Crick in 1953, we knew that genes were nucleotides arranged in a double helix. Great. And we knew about mutation. So by the late twentieth century, we have a theory of natural selection which says that mutations arise spontaneously in genes, that the environment favors the mutations that are beneficial, and out of this selection process evolution occurs. It’s simple and straightforward. God is not at work. No higher organizing principle involved. In the end, evolution is just the result of a bunch of mutations that either Survive or die. Right?”
“Right,” Arby said.
“But there are problems with that idea,” Malcolm said. “First of all, there’s a time problem. A single bacterium – the earliest form of life has two thousand enzymes. Scientists have estimated how long it would take to randomly assemble those enzymes from a primordial soup. Estimates run from forty billion years to one hundred billion years. But the earth is only four billion years old. So, chance alone seems too slow. Particularly since we know bacteria actually appeared only four hundred million years after the earth began. Life appeared very fast – which is why some scientists have decided life on earth must be of extraterrestrial origin. Although I think that’s just evading the issue.”
“Okay…”
“Second, there’s the coordination problem. If you believe the current theory, then all the wonderful complexity of life is nothing but the accumulation of chance events – a bunch of genetic accidents strung together. Yet when we look closely at animals, it appears as if many elements must have evolved simultaneously. Take bats, which have echolocation-they navigate by sound. To do that, many things must evolve. Bats need a specialized apparatus to make sounds, they need specialized ears to hear echoes, they need specialized brains to interpret the sounds, and they need specialized bodies to dive and swoop and catch insects. If all these things don’t evolve simultaneously, there’s no advantage. And to imagine all these things happen purely by chance is like imagining that a tornado can hit a junkyard and assemble the Parts into a working 747 airplane. It’s very hard to believe.”
“Okay,” Thorne said. “I agree.”
“Next problem. Evolution doesn’t always act like a blind force should. Certain environmental niches don’t get filled. Certain plants don’t get eaten. And certain animals don’t evolve much. Sharks haven’t changed for a hundred and sixty million years. Opossums haven’t changed since dinosaurs became extinct, sixty-five million years ago. The environments for these animals have changed dramatically, but the animals have remained almost the same. Not exactly the same, but almost. In other words, it appears they haven’t responded to their environment.”
“Maybe they’re still well adapted,” Arby said.
“Maybe. Or maybe there’s something else going on that we don’t understand.”
” Like what?”
“Like other rules that influence the outcome.”
Thorne said, “Are you saying evolution is directed?”
“No,” Malcolm said. “That’s Creationism and it’s wrong. Just plain wrong. But I am saying that natural selection acting on genes is probably not the whole story. It’s too simple. Other forces are also at work. The hemoglobin molecule is a protein that is folded like a sandwich around a central iron atom that binds oxygen. Hemoglobin expands and contracts when it takes on and gives up oxygen-like a tiny molecular lung. Now, we know the sequence of amino acids that make up hemoglobin. But we don’t know how to fold it. Fortunately, we don’t need to know that, because if you make the molecule, it folds all by itself. It organizes itself. And it turns out, again and again, that living things seem to have a self-organizing quality. Proteins fold. Enzymes interact. Cells arrange themselves to form organs and the organs arrange themselves to form a coherent individual. Individuals organize themselves to make a population. And populations organize themselves to make a coherent biosphere. From complexity theory, we’re starting to have a sense of how this self-organization may happen, and what it means. And it implies a major change in how we view evolution.”