Before the 20th century, not a single human being had an explicit concept of "inclusive genetic fitness", the sole and absolute obsession of the blind idiot god. We have no instinctive revulsion of condoms or oral sex. Our brains, those supreme reproductive organs, don't perform a check for reproductive efficacy before granting us sexual pleasure.

Why not? Why aren't we consciously obsessed with inclusive genetic fitness? Why did the Evolution-of-Humans Fairy create brains that would invent condoms? "It would have been so easy," thinks the human, who can design new complex systems in an afternoon.

The Evolution Fairy, as we all know, is obsessed with inclusive genetic fitness. When she decides which genes to promote to universality, she doesn't seem to take into account anything except the number of copies a gene produces. (How strange!)

But since the maker of intelligence is thus obsessed, why not create intelligent agents - you can't call them humans - who would likewise care purely about inclusive genetic fitness? Such agents would have sex only as a means of reproduction, and wouldn't bother with sex that involved birth control. They could eat food out of an explicitly reasoned belief that food was necessary to reproduce, not because they liked the taste, and so they wouldn't eat candy if it became detrimental to survival or reproduction. Post-menopausal women would babysit grandchildren until they became sick enough to be a net drain on resources, and would then commit suicide.

It seems like such an obvious design improvement - from the Evolution Fairy's perspective.

Now it's clear, as was discussed yesterday, that it's hard to build a powerful enough consequentialist. Natural selection sort-of reasons consequentially, but only by depending on the actual consequences. Human evolutionary theorists have to do really high-falutin' abstract reasoning in order to imagine the links between adaptations and reproductive success.

But human brains clearly can imagine these links in protein. So when the Evolution Fairy made humans, why did It bother with any motivation except inclusive genetic fitness?

It's been less than two centuries since a protein brain first represented the concept of natural selection. The modern notion of "inclusive genetic fitness" is even more subtle, a highly abstract concept. What matters is not the number of shared genes. Chimpanzees share 95% of your genes. What matters is shared genetic variance, within a reproducing population - your sister is one-half related to you, because any variations in your genome, within the human species, are 50% likely to be shared by your sister.

Only in the last century - arguably only in the last fifty years - have evolutionary biologists really begun to understand the full range of causes of reproductive success, things like reciprocal altruism and costly signaling. Without all this highly detailed knowledge, an intelligent agent that set out to "maximize inclusive fitness" would fall flat on its face.

So why not preprogram protein brains with the knowledge? Why wasn't a concept of "inclusive genetic fitness" programmed into us, along with a library of explicit strategies? Then you could dispense with all the reinforcers. The organism would be born knowing that, with high probability, fatty foods would lead to fitness. If the organism later learned that this was no longer the case, it would stop eating fatty foods. You could refactor the whole system. And it wouldn't invent condoms or cookies.

This looks like it should be quite possible in principle. I occasionally run into people who don't quite understand consequentialism, who say, "But if the organism doesn't have a separate drive to eat, it will starve, and so fail to reproduce." So long as the organism knows this very fact, and has a utility function that values reproduction, it will automatically eat. In fact, this is exactly the consequentialist reasoning that natural selection itself used to build automatic eaters.

What about curiosity? Wouldn't a consequentialist only be curious when it saw some specific reason to be curious? And wouldn't this cause it to miss out on lots of important knowledge that came with no specific reason for investigation attached? Again, a consequentialist will investigate given only the knowledge of this very same fact. If you consider the curiosity drive of a human - which is not undiscriminating, but responds to particular features of problems - then this complex adaptation is purely the result of consequentialist reasoning by DNA, an implicit representation of knowledge: Ancestors who engaged in this kind of inquiry left more descendants.

So in principle, the pure reproductive consequentialist is possible. In principle, all the ancestral history implicitly represented in cognitive adaptations can be converted to explicitly represented knowledge, running on a core consequentialist.

But the blind idiot god isn't that smart. Evolution is not a human programmer who can simultaneously refactor whole code architectures. Evolution is not a human programmer who can sit down and type out instructions at sixty words per minute.

For millions of years before hominid consequentialism, there was reinforcement learning. The reward signals were events that correlated reliably to reproduction. You can't ask a nonhominid brain to foresee that a child eating fatty foods now will live through the winter. So the DNA builds a protein brain that generates a reward signal for eating fatty food. Then it's up to the organism to learn which prey animals are tastiest.

DNA constructs protein brains with reward signals that have a long-distance correlation to reproductive fitness, but a short-distance correlation to organism behavior. You don't have to figure out that eating sugary food in the fall will lead to digesting calories that can be stored fat to help you survive the winter so that you mate in spring to produce offspring in summer. An apple simply tastes good, and your brain just has to plot out how to get more apples off the tree.

And so organisms evolve rewards for eating, and building nests, and scaring off competitors, and helping siblings, and discovering important truths, and forming strong alliances, and arguing persuasively, and of course having sex...

When hominid brains capable of cross-domain consequential reasoning began to show up, they reasoned consequentially about how to get the existing reinforcers. It was a relatively simple hack, vastly simpler than rebuilding an "inclusive fitness maximizer" from scratch. The protein brains plotted how to acquire calories and sex, without any explicit cognitive representation of "inclusive fitness".

A human engineer would have said, "Whoa, I've just invented a consequentialist! Now I can take all my previous hard-won knowledge about which behaviors improve fitness, and declare it explicitly! I can convert all this complicated reinforcement learning machinery into a simple declarative knowledge statement that 'fatty foods and sex usually improve your inclusive fitness'. Consequential reasoning will automatically take care of the rest. Plus, it won't have the obvious failure mode where it invents condoms!"

But then a human engineer wouldn't have built the retina backward, either.

The blind idiot god is not a unitary purpose, but a many-splintered attention. Foxes evolve to catch rabbits, rabbits evolve to evade foxes; there are as many evolutions as species. But within each species, the blind idiot god is purely obsessed with inclusive genetic fitness. No quality is valued, not even survival, except insofar as it increases reproductive fitness. There's no point in an organism with steel skin if it ends up having 1% less reproductive capacity.

Yet when the blind idiot god created protein computers, its monomaniacal focus on inclusive genetic fitness was not faithfully transmitted. Its optimization criterion did not successfully quine. We, the handiwork of evolution, are as alien to evolution as our Maker is alien to us. One pure utility function splintered into a thousand shards of desire.

Why? Above all, because evolution is stupid in an absolute sense. But also because the first protein computers weren't anywhere near as general as the blind idiot god, and could only utilize short-term desires.

In the final analysis, asking why evolution didn't build humans to maximize inclusive genetic fitness, is like asking why evolution didn't hand humans a ribosome and tell them to design their own biochemistry. Because evolution can't refactor code that fast, that's why. But maybe in a billion years of continued natural selection that's exactly what would happen, if intelligence were foolish enough to allow the idiot god continued reign.

The Mote in God's Eye by Niven and Pournelle depicts an intelligent species that stayed biological a little too long, slowly becoming truly enslaved by evolution, gradually turning into true fitness maximizers obsessed with outreproducing each other. But thankfully that's not what happened. Not here on Earth. At least not yet.

So humans love the taste of sugar and fat, and we love our sons and daughters. We seek social status, and sex. We sing and dance and play. We learn for the love of learning.

A thousand delicious tastes, matched to ancient reinforcers that once correlated with reproductive fitness - now sought whether or not they enhance reproduction. Sex with birth control, chocolate, the music of long-dead Bach on a CD.

And when we finally learn about evolution, we think to ourselves: "Obsess all day about inclusive genetic fitness? Where's the fun in that?"

The blind idiot god's single monomaniacal goal splintered into a thousand shards of desire. And this is well, I think, though I'm a human who says so. Or else what would we do with the future? What would we do with the billion galaxies in the night sky? Fill them with maximally efficient replicators? Should our descendants deliberately obsess about maximizing their inclusive genetic fitness, regarding all else only as a means to that end?

Being a thousand shards of desire isn't always fun, but at least it's not boring. Somewhere along the line, we evolved tastes for novelty, complexity, elegance, and challenge - tastes that judge the blind idiot god's monomaniacal focus, and find it aesthetically unsatisfying.

And yes, we got those very same tastes from the blind idiot's godshatter. So what?