03/08/2020 (Sun) 11:11:50
Where do taste buds come from? Not from an intelligent designer visualizing their consequences, but from a frozen history of ancestry: Adam liked sugar and ate an apple and reproduced, Barbara liked sugar and ate an apple and reproduced, Charlie liked sugar and ate an apple and reproduced, and 2763 generations later, the allele became fixed in the population. For convenience of thought, we sometimes compress this giant history and say: "Evolution did it." But it's not a quick, local event like a human designer visualizing a screwdriver. This is the objective cause of a taste bud.
What is the objective shape of a taste bud? Technically, it's a molecular sensor connected to reinforcement circuitry. This adds another level of indirection, because the taste bud isn't directly acquiring food. It's influencing the organism's mind, making the organism want to eat foods that are similar to the food just eaten.
What is the objective consequence of a taste bud? In a modern First World human, it plays out in multiple chains of causality: from the desire to eat more chocolate, to the plan to eat more chocolate, to eating chocolate, to getting fat, to getting fewer dates, to reproducing less successfully. This consequence is directly opposite the key regularity in the long chain of ancestral successes which caused the taste bud's shape. But, since overeating has only recently become a problem, no significant evolution (compressed regularity of ancestry) has further influenced the taste bud's shape.
What is the meaning of eating chocolate? That's between you and your moral philosophy. Personally, I think chocolate tastes good, but I wish it were less harmful; acceptable solutions would include redesigning the chocolate or redesigning my biochemistry.
Smushing several of the concepts together, you could sort-of-say, "Modern humans do today what would have propagated our genes in a hunter-gatherer society, whether or not it helps our genes in a modern society." But this still isn't quite right, because we're not actually asking ourselves which behaviors would maximize our ancestors' inclusive fitness. And many of our activities today have no ancestral analogue. In the hunter-gatherer society there wasn't any such thing as chocolate.
So it's better to view our taste buds as an adaptation fitted to ancestral conditions that included near-starvation and apples and roast rabbit, which modern humans execute in a new context that includes cheap chocolate and constant bombardment by advertisements.
Therefore it is said: Individual organisms are best thought of as adaptation-executers, not fitness-maximizers.