In Part 5. of this series (which starts here), I introduced the notion of a molecule that copies. And if you remember, the copying did not occur with complete fidelity—that is, the copy was not an exact duplicate of the original.

Now, I’m going to refer to this infidelity as a “mistake” or “error”, but I’d like to point out that strictly speaking it’s not a mistake or error at all—because there’s no intention behind the copying. Simply, the molecule that copies doesn’t make exact copies, that’s just the way it is—it’s not “trying” to do it “right”, and therefore it cannot make mistakes or introduce errors. I’m using those words because it’s easier to type “error” than “a copy without perfect fidelity.”

So by way of review, let’s put together what we have so far in the Model of Everything:

In the past 5 posts we’ve managed to get from sub-atomic particles to the emergence of simple life forms, but clearly we’ve got to account for the vast gap between the kind of life in the diagram above to the complex beings that we are. And yet the gap is bridged by a rather simple process: natural selection.

Just as oceans build beaches by the accumulation of tiny grains of sand—given enough time, tiny copying mistakes can yield an amazing diversity of life. How can the accumulation of errors result in such an assortment? Because natural selection saves what works.

As soon as an error provides an advantage, it is saved. How? By the organism’s survival. The surviving organism’s offspring, then—armed with that beneficial change—not only carry the change forward, but also create changes to the change. Why? Because in the business of making copies, mistakes never stop.

Of course other factors add to the final result of all this change, copies that find themselves in water will survive if their random mistakes allow the organism to better live in water, and those on land will survive with an accumulation of land-mistakes. In the end, the variety is wonderful:

Yes, we are the spat-out guts of dead stars combined and recombined through billions of years of accumulated successful mistakes. T-Rexes, narwhals, cute little kittens, George Bush—we all share this amazing pedigree.

NEXT: Part 7. The Inner Life of Living Things