The world is divided into things that look designed (like birds and airliners) and things that don't (rocks and mountains). Things that look designed are divided into those that really are designed (submarines and tin openers) and those that aren't (sharks and hedgehogs). The diagnostic of things that look (or are) designed is that their parts are assembled in ways that are statistically improbable in a functional direction. They do something well: for instance, fly.
Darwinian natural selection can produce an uncanny illusion of design. An engineer would be hard put to decide whether a bird or a plane was the more aerodynamically elegant.
So powerful is the illusion of design, it took humanity until the mid-19th century to realise that it is an illusion. In 1859, Charles Darwin announced one of the greatest ideas ever to occur to a human mind: cumulative evolution by natural selection. Living complexity is indeed orders of magnitude too improbable to have come about by chance. But only if we assume that all the luck has to come in one fell swoop. When cascades of small chance steps accumulate, you can reach prodigious heights of adaptive complexity. That cumulative build-up is evolution. Its guiding force is natural selection.
Every living creature has ancestors, but only a fraction have descendants. All inherit the genes of an unbroken sequence of successful ancestors, none of whom died young and none of whom failed to reproduce. Genes that program embryos to develop into adults who can successfully reproduce automatically survive in the gene pool, at the expense of genes that fail. This is natural selection at the gene level, and we notice its consequences at the organism level. There has to be an ultimate source of new genetic variation, and it is mutation. Copies of newly mutated genes are reshuffled through the gene pool by sexual reproduction, and selection removes them from the pool in a way that is non-random.
- Richard Dawkins
Good stuff. I always thought of darwinian ideas as being applicable at the species or population level, but mom helped me think about it on the cellular level too.
She asked, "What makes a cell divide?" I think that, on the surface at least, its programming. DNA, RNA, proteins, the entire chemistry system of a cell works to ultimately dictate behavior, because we’re talking about the behavior of atoms first, molecules second, compounds, substances, solutions, eventually cell organs, and then the cell itself. It divides when its programming dictates that it do so.
So the ineviteable next question is where does the programming come from? A really crappy, but true answer is: other programming. The programming of the parent cell that divided to make this cell and another. So what caused the first program? Chance? Maybe just the right mixture of elements at the right time under the right conditions in the primordial ooze? No one knows. Which is why people have the opportunity to inject what they believe.