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>Genetic inheritance via epigenetic pathways is extremely rare and basically irrelevant. It explains essentially 0% of the evolved traits that you see in humans

by x220 8y ago

>Genetic inheritance via epigenetic pathways is extremely rare and basically irrelevant. It explains essentially 0% of the evolved traits that you see in humans and other complex organisms. I would like a source to read more about this. I don't distrust you. I'm genuinely interested in reading more about this. >And none of our important traits were acquired by conscious processes on the parts of our ancestors I think humans sexually select for intelligence, because it's a trait that affects how high up a human can climb across different social hierarchies.

toasterlovin 8y ago
> I would like a source to read more about this. I don't distrust you. I'm genuinely interested in reading more about this. Sorry, I don't have a source. Epigenetic changes in somatic cells (all the cells in your body except for your sperm or egg cells) are common and necessary for the differentiation that takes place as cells divide and multiply to create a growing organism. But epigenetic inheritance is rare, because epigenetic changes can only be inherited if they somehow change the DNA in germ line cells (sperm or eggs). There just aren't many plausible ways for stuff that happens in the environment to modify the DNA in sperm or eggs. The most plausible way would be for some sort of systemic stress. And, IIRC, one of the only known instances of epigenetic inheritance was a result of starvation. But, more generally, epigenetic inheritance has to be rare. Evolution is a balancing act. On the one hand you need some mutation, because otherwise there is no variation against which natural selection can act. But on the other hand, you need to limit the amount of mutation so that beneficial genes can persist through time (otherwise they cease to be beneficial), and so that the crazy house of cards that is a developing organism doesn't collapse. If you know anything about how complex organisms work, it's absolutely insane. There is almost none of the abstraction and encapsulation that we use in engineering to manage complexity. Instead, everything effects everything else. Evolution is like building a computer program by mutating individual bits in a binary program. If you play that out in a massively parallel fashion over billions of iterations, you can get some programs that do really cool stuff. But they would be incredibly brittle. It would be incredibly easy to crash the whole thing by mutating the wrong bit. And these types of catastrophic mutations seem pretty common in complex organisms. Among humans, the miscarriage rate is 30%-50% (according to Wikipedia; look up the Miscarriage article). A significant number of those are believed to be caused by the female rejecting the fetus because of defects of some kind. All of this is a long way of saying that it's simply not believable that there is some process which is introducing significant mutation into the reproductive process.
- x220 8y ago
  Thanks for the info!

by x220 8y ago

toasterlovin 8y ago

> I would like a source to read more about this. I don't distrust you. I'm genuinely interested in reading more about this. Sorry, I don't have a source. Epigenetic changes in somatic cells (all the cells in your body except for your sperm or egg cells) are common and necessary for the differentiation that takes place as cells divide and multiply to create a growing organism. But epigenetic inheritance is rare, because epigenetic changes can only be inherited if they somehow change the DNA in germ line cells (sperm or eggs). There just aren't many plausible ways for stuff that happens in the environment to modify the DNA in sperm or eggs. The most plausible way would be for some sort of systemic stress. And, IIRC, one of the only known instances of epigenetic inheritance was a result of starvation. But, more generally, epigenetic inheritance has to be rare. Evolution is a balancing act. On the one hand you need some mutation, because otherwise there is no variation against which natural selection can act. But on the other hand, you need to limit the amount of mutation so that beneficial genes can persist through time (otherwise they cease to be beneficial), and so that the crazy house of cards that is a developing organism doesn't collapse. If you know anything about how complex organisms work, it's absolutely insane. There is almost none of the abstraction and encapsulation that we use in engineering to manage complexity. Instead, everything effects everything else. Evolution is like building a computer program by mutating individual bits in a binary program. If you play that out in a massively parallel fashion over billions of iterations, you can get some programs that do really cool stuff. But they would be incredibly brittle. It would be incredibly easy to crash the whole thing by mutating the wrong bit. And these types of catastrophic mutations seem pretty common in complex organisms. Among humans, the miscarriage rate is 30%-50% (according to Wikipedia; look up the Miscarriage article). A significant number of those are believed to be caused by the female rejecting the fetus because of defects of some kind. All of this is a long way of saying that it's simply not believable that there is some process which is introducing significant mutation into the reproductive process.

x220 8y ago
Thanks for the info!