An example I love of a helpful brain adaptation with few downsides that I know of, which hasn’t spread far throughout mammals is one in seal brains. Seals, unlike whales and dolphins, had an evolutionary niche which caused them to not get as good at holding their breathe as would be optimal for them. They had many years of occasionally diving too deep and dying from brain damage related to oxygen deprivation (ROS in neurons). So, some ancient seal had a lucky mutation that gave them a cool trick. The glial cells which support neurons can easily grow back even if their population gets mostly wiped out. Seals have extra mitochondria in their glial cells and none in their neurons, and export the ATP made in the glial cells to the neurons. This means that the reactive oxygen species from oxygen deprivation of the mitochondria all occur in the glia. So, when a seal stays under too long, their glial cells die instead of their neurons. The result is that they suffer some mental deficiencies while the glia grow back over a few days or a couple weeks (depending on the severity), but then they have no lasting damage. Unlike in other mammals, where we lose neurons that can’t grow back.
Given enough time, would humans evolve the same adaptation (if it does turn out to have no downsides)? Maybe, but probably not. There just isn’t enough reproductive loss due to stroke/oxygen-deprivation to give a huge advantage to the rare mutant who lucked into it.
But since we have genetic engineering now… we could just give the ability to someone. People die occasionally competing in deep freediving competitions, and definitely get brain damage. I bet they’d love to have this mod if it were offered.
An example I love of a helpful brain adaptation with few downsides that I know of, which hasn’t spread far throughout mammals is one in seal brains. Seals, unlike whales and dolphins, had an evolutionary niche which caused them to not get as good at holding their breathe as would be optimal for them. They had many years of occasionally diving too deep and dying from brain damage related to oxygen deprivation (ROS in neurons). So, some ancient seal had a lucky mutation that gave them a cool trick. The glial cells which support neurons can easily grow back even if their population gets mostly wiped out. Seals have extra mitochondria in their glial cells and none in their neurons, and export the ATP made in the glial cells to the neurons. This means that the reactive oxygen species from oxygen deprivation of the mitochondria all occur in the glia. So, when a seal stays under too long, their glial cells die instead of their neurons. The result is that they suffer some mental deficiencies while the glia grow back over a few days or a couple weeks (depending on the severity), but then they have no lasting damage. Unlike in other mammals, where we lose neurons that can’t grow back.
Given enough time, would humans evolve the same adaptation (if it does turn out to have no downsides)? Maybe, but probably not. There just isn’t enough reproductive loss due to stroke/oxygen-deprivation to give a huge advantage to the rare mutant who lucked into it.
But since we have genetic engineering now… we could just give the ability to someone. People die occasionally competing in deep freediving competitions, and definitely get brain damage. I bet they’d love to have this mod if it were offered.