I’m listening to a book called “Your Inner Fish” by Neil Shubin. The beginning of the book struck me again with a hard truth about evolution, maybe one of the hard truths that makes evolution so hard for people to really, really accept.

And it is hard. It’s not just stupidity or ignorance or willful neglect of the facts. There’s something unsettling about the whole idea of evolution, and Shubin’s book reminded me of it again.

Shubin was interested in the origin of tetrapods. He went looking for a fossil that would show the transition from fish to amphibian, and he found it in a creature called Tiktaalik. Tiktaalik is very much midway between water-living fish and land-living tetrapods. While it has scales and fins, those fins contain finger and wrist bones, showing that Tiktaalik sometimes supported its own weight. More obvious upon first glance, though, is that Tiktaalik has a neck.

According to Shubin, this was a key development. Fish never have necks; their heads are attached directly to their shoulders. But Tiktaalik has evolved a neck.

And this is where, if you think enough about it, things get uncomfortable. What does it mean that Tiktaalik evolved a neck? It means that over a great many generations, a fish ancestor had enough variation in its offspring that a tendency toward “neckiness” was advantageous. But evolution can have no direction. There must have been lots of other variation, too, most of which led – nowhere.

But what does nowhere mean? It means death. Most creatures with variations from the norm die. Most creatures with variations never reproduce, and so their genes don’t contribute to the future. From this pruning – a pruning whose immediate cause is differential reproduction but whose ultimate cause, almost always, is death – comes the “direction” we sometimes see in a directionless process.

It’s maybe not so uncomfortable when we think about fish. But when it comes closer to home, this differential reproduction, caused most often by death, becomes a lot more personal. I like to think of my daughters as new voices added to the universal song, seeds of individualism, hope, and potential, another chance for the universe to know itself. I like to think of them, in other words, as anything other than what we know, via evolution, what they are. They are variations in the genome, dice rolled across the field of natural selection. Perhaps the dice have come up with positive variations, perhaps the dice this time came up negative. It’s not something I can control, and its not something I can stop.

The strategy becomes clear when you think about something like the HIV virus. HIV is dangerous, partly because it is rotten at reproducing itself. When HIV reproduces, it creates millions of approximate copies of itself, with lots of variation mixed in. Most varieties won’t be very good, but that’s no big deal to HIV, with its myriad offspring. The sacrifice of so many useless viruses is worth it for the chance to create a variety even better at what it does. And so HIV keeps avoiding our efforts to pin it down.

The basic idea works in the animal kingdom, too. Every “invention” of natural selection is produced on a pile of death, countless failed experiments that resulted in a life that was nasty, brutish, and short. Life is uncertain, reproduction is a risky proposition, and evolution is the direct result of that uncertain risk.

This, by the way, is a perfect example of the difference between what is and what ought. Evolution is a fact. It is the way the world works. However, that doesn’t make it a model for society. Evolution is brutish. It is without forethought. It made us quite by accident. But now we’re here. We can crash the party. We can hold evolution off, at least some of its more unpleasant aspects. We can care for individuals with variation, because we recognize that natural selection is not the measure of all things. We can choose to cherish a few offspring, instead of flooding the world with as many copies as we can, hoping a few will turn out. We can even plan ahead, to avoid genetic combinations that stack the dice against our children before they’re even conceived.

Probably that last bit makes some people cringe. Again, that’s this discomfort with the fact of evolution coming through. Reproduction is throwing dice. Which is more cruel, to allow deadly variation to happen, or to fix the game to avoid its consequences?

Remember the fish’s neck, and all the dead creatures on which that neck was built. Evolution is hard.