The Monarch butterfly takes an extraordinarily long migration path and it requires five generations of butterflies to accomplish it This means five generations for the complete point-to-point turnaround, starting in Mexico and the fifth generation returning. So how did the fifth generation know how to find its way back. Learn more of their migration at Monarch Butterfly Fund: The Monarch Butterfly's Annual Cycle.
It dawned on me the long path is because of the retreat of the last Ice Age. That was roughly fifty thousand years ago. That they knew to do that had to have come from surviving previous Ice Ages.
They must have in their little butterfly minds to fly North so long as the weather is getting warmer or turn South if it ain't. Apart from that and thoughts of finding nectar and hot sex with a lady butterfly, there probably isn't room for too much else in a butterfly brain.
That simple logic gives them the flexibility to survive any Ice Age so long as a at least a few make it. At the extreme of an Ice Age, they probably would not migrate far at all, it wouldn't be possible and it wouldn't get so hot they would need to leave where they are. As the ice recedes, they follow it and the milkweed and they start sooner because Spring comes earlier. They don't follow it because Butterfly Einstein says it's time but rather they don't like increasing heat.
The earliest Ice Ages must have given them the tolerance for the heat at the southern extreme of their migration. Those that couldn't survive it died out with the most heat-tolerant Monarchs living on in Mexico. They don't like it too hot so they move when the temperature goes up. That part is all straight-up and makes sense.
But then it gets weird.
The last generation of butterflies to fly back South goes through major physiological changes as the emerging butterfly is not capable of sex so it's useless for anything but migration.
So, Dagwood, this is where yer evolution gets all chicken and the egg-like. Why should a Monarch butterfly happily living in Mexico evolve complex biological changes such that it can fly long distances. It's a happy butterfly, it's already home. It makes no sense such a mechanism should evolve as there's no pressure to drive it.
Which means they must have already known how to do it or how would little butterfly brain figure it out. The butterflies in the North must have lived in an interglacial period and came up with the change to delay the onset of sexual maturity, etc that permitted migration. The other Monarchs would have no reason, there's no force driving them.
That seems reasonable to generally explain the basis for evolution of the ability to do the migration.
It doesn't go anywhere near figuring out how they find their way to Mexico. If their only instinct is to fly South then most of them will end up in the Gulf of Mexico learning to swim.
So ...
How about that is exactly how it worked and most of the returning butterflies didn't make it as swimmers ... but ... the ones that did wound up in Mexico. Those are the ones to turn around and migrate back around again and those ones know where they start. Since they are the only ones left, that process is repeated every season until somehow a map gets stuck into the DNA as how else will Monarch Generation 5 know the way back to somewhere it has never been.
The only other way they could know is if they are told in Butterfly Language or they use telepathy. Good science shouldn't rule out anything but that's complete crap (maybe).
That general mechanism should work for how they figured out how to do it so, once they knew, where they did they store it. I imagine there's a Nobel Prize for whomever figures out how that works. So, um, go forth and be a genius there, Dagwood. Someone will. Maybe someone already did.
It dawned on me the long path is because of the retreat of the last Ice Age. That was roughly fifty thousand years ago. That they knew to do that had to have come from surviving previous Ice Ages.
They must have in their little butterfly minds to fly North so long as the weather is getting warmer or turn South if it ain't. Apart from that and thoughts of finding nectar and hot sex with a lady butterfly, there probably isn't room for too much else in a butterfly brain.
That simple logic gives them the flexibility to survive any Ice Age so long as a at least a few make it. At the extreme of an Ice Age, they probably would not migrate far at all, it wouldn't be possible and it wouldn't get so hot they would need to leave where they are. As the ice recedes, they follow it and the milkweed and they start sooner because Spring comes earlier. They don't follow it because Butterfly Einstein says it's time but rather they don't like increasing heat.
The earliest Ice Ages must have given them the tolerance for the heat at the southern extreme of their migration. Those that couldn't survive it died out with the most heat-tolerant Monarchs living on in Mexico. They don't like it too hot so they move when the temperature goes up. That part is all straight-up and makes sense.
But then it gets weird.
The last generation of butterflies to fly back South goes through major physiological changes as the emerging butterfly is not capable of sex so it's useless for anything but migration.
So, Dagwood, this is where yer evolution gets all chicken and the egg-like. Why should a Monarch butterfly happily living in Mexico evolve complex biological changes such that it can fly long distances. It's a happy butterfly, it's already home. It makes no sense such a mechanism should evolve as there's no pressure to drive it.
Which means they must have already known how to do it or how would little butterfly brain figure it out. The butterflies in the North must have lived in an interglacial period and came up with the change to delay the onset of sexual maturity, etc that permitted migration. The other Monarchs would have no reason, there's no force driving them.
That seems reasonable to generally explain the basis for evolution of the ability to do the migration.
It doesn't go anywhere near figuring out how they find their way to Mexico. If their only instinct is to fly South then most of them will end up in the Gulf of Mexico learning to swim.
So ...
How about that is exactly how it worked and most of the returning butterflies didn't make it as swimmers ... but ... the ones that did wound up in Mexico. Those are the ones to turn around and migrate back around again and those ones know where they start. Since they are the only ones left, that process is repeated every season until somehow a map gets stuck into the DNA as how else will Monarch Generation 5 know the way back to somewhere it has never been.
The only other way they could know is if they are told in Butterfly Language or they use telepathy. Good science shouldn't rule out anything but that's complete crap (maybe).
That general mechanism should work for how they figured out how to do it so, once they knew, where they did they store it. I imagine there's a Nobel Prize for whomever figures out how that works. So, um, go forth and be a genius there, Dagwood. Someone will. Maybe someone already did.
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