How do pigeons feed their babies

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> We can imagine that once such a device such as 'desire' is given, that they would mate, without knowing the implications to it. But this would mean that the hen would simply lay the eggs wherever, and then leave them to die. But they don't. They build a nest, I mean, a nest! Why? You’re jumping from the evolution of mating behavior to the evolution of nest building, and you seem to be assuming it all evolved independently in moorhens! Basic mating behavior would have been one of the very first things to evolve in animals. Presumably the precursor would have involved species that simply released their gametes into the Precambrian waters, similar to what corals still do today. So there’s no need to envision early moorhens running around wondering how they might maintain the species. They inherited their mating behaviors (slightly modified) from their immediate ancestors, who inherited them (slightly modified) from their immediate ancestors, and so on going back half a billion years. As for nesting behavior, that presumably dates back to sometime around the time of the dinosaurs. But even before the first nest made of grass and twigs there were presumably species making nests by scooping out depressions in the dirt. And before that there were likely species that dug holes in the dirt in which to leave their eggs. And before that there still would have been a very long line of ancestral species that took care to lay their eggs in specific places that had specific characteristics. So how did any of them know what to look for? They didn’t. That’s not how instinct works. When you itch do you consider that the source of your discomfort may be a patch of old skin, or possibly some type of ectoparasite, and reason that by vigorously rubbing your fingernails over the area you would be likely to remove either of those things? No, you are presented with an uncomfortable sensation on your skin which (if you are very young) you have no idea what to do about. As you move around you are likely to brush the itchy area on something, at which point you get some sense of relief, and eventually you figure out that by directly scratching you can get lots of relief and in fact direct pleasure. The same thing presumably applies to nest building. The parents-to-be undergo specific cues when in specific hormonal states, and they feel uncomfortable. They find they can lessen the discomfort by doing some of the motions of building a nest, and that they can gain direct pleasure by actually building the nest. If the nest doesn’t look right as it’s being built, they will remain uncomfortable until it is fixed, whereupon they gain pleasure. Presumably, looking “right” would mean looking like the nest they grew up in, with regard to particulars of shape and construction established by what they may have had an instinctual predilection to pay attention to. Later, when the female needs a place to lay her eggs, she’ll look around and lo and behold there will be a nest! What luck! And again she will feel pleasure if she lays the eggs there and discomfort if she does not. And all these cues of pleasure and discomfort occur in moorhens because they were inherited (slightly modified) from their immediate ancestors. And those individuals in the past that modified the nest-building behavior in maladaptive ways, left fewer descendants. > It must then go back to an earlier time within the DNA level; these 'instincts' must have been programmed in. As I hope I’ve shown, they were evolved in, over a long series of minor modifications. But consider what would happen if some higher intelligence were to program in some form of genetically based instinct that wouldn't be useful for millions of years. Our non-primate ancestors could produce their own vitamin C. Monkeys and apes retain the gene for doing that, but deleterious mutations have rendered it unworkable. We are left having to obtain vitamin C from our food. If we can’t do that we get scurvy and eventually die. The reason this happens is that mutations in our primate ancestors that modified the vitamin C gene so that it wouldn’t work, were not removed from the population by natural selection. The individuals that had lost the ability to make their own vitamin C still lived to reproduce, because they got all the vitamin C they needed from their normal diet. So generally speaking, if a species has a gene that isn’t currently providing a benefit, but that could be expected to provide a benefit to descendants far removed, that gene will be damaged before the descendants inherit it. In evolution, you have to use it (now) or lose it. Your “programmed” genes, if they existed, would be broken by the time they were inherited by the descendant species for which they were intended.