Time enough for evolution?

[Gawdzilla Sama]

There’s plenty of time for evolution

One of the most common problems that laypeople have with evolution is that there doesn’t seem to have been enough time for it. Given the idea that evolution is relatively slow, and yet there’s been an enormous amount of change since the first species a few billion years ago, how could natural selection (and other processes like genetic drift) have built all these exquisite, functioning organisms?

Part of the answer, of course, is that people fail to appreciate “deep time,” since we’re evolved to regard life over years and decades, not millions and billions of years. Evolutionists often demonstrate this by compressing all of evolution into a calendar year, showing how much evolution has occurred in a short segment of that time. Using this analogy in WEIT, for example, I show that the divergence between the ancestors of humans and chimps would have occurred only at 6 a.m. on December 31.

Another difficulty is that people assume that if one species evolves into another by changing many traits, it seems highly unlikely that they can all change at the same time by simultaneous fixation of adaptive mutations. If evolutionary change of a species involves gene substitution at L genes (with L being a number), and the proportion of all genes in each generation that are more favored than the “primitive” type is 1/K (this number is low because most mutations are deleterious), then the number of “trials” it takes to get adaptive mutations at all the genes is on the order of KL . In other words, each generation new mutations arise, and if adaptive ones aren’t there for every gene required to make a descendant from an ancestor, then that whole trial is discarded and the process starts the next generation. Finally, after about KL generations have passed, you’ll get the right type.

But that can take a huge amount of time. If you want to change 20,000 genes, for example, with only 1/40 of all segregating mutational variants being advantageous, then it would take 1034,040 “trials” (roughly the time it takes for a new adaptive mutation to become fixed) to effect this change. This could never occur, since even with an organism having 100 generations per year and with a “trial” equivalent to one generation, this would take a number of years equal to 10 followed by 34,038 zeroes. (Since life began there’s only been about 3 followed by nine zeroes years.) That’s not long enough!

Balance of article at URL above.