> He and collaborator Ali Akbari just published a paper that overturns a long-standing consensus about human evolution — that natural selection has been dormant in our species since the agricultural revolution
Citation needed! Sounds highly implausible! So I asked ChatGPT "Is there a consensus that natural selection has been dormant in our species since the agricultural revolution?" It said:
> No. There is no scientific consensus that natural selection in humans became “dormant” after the agricultural revolution. In fact, the mainstream view in evolutionary biology is almost the opposite: humans have continued evolving, and in some cases may even have experienced new selective pressures after agriculture emerged.
Outstanding! Fascinating and brilliant! Kudos to both participants.
Question: Is there not an ambiguity in the “ancestor-descendant” terminology? In the common, straightforward sense, your “ancestors” are your parents, their parents, their parents, etc.; you are “descended” from all the people (and proto-people) in your family tree. But in another sense, we might say you are “descended” only from those from whom you have derived at least one gene (or other significant bit of genetic material). This will probably (I haven’t done the calculation) be a small minority of those in your family tree: given the small total number of your genes, you inherited nothing from most of your ancestors-in-the-first-sense who were living as recently as the high middle ages. (Serious inbreeding would modify this result). Do we not think of our real ancestors as those from whom we have derived our genes? This would be using ‘ancestor’ in my second sense.
In trying to answer the question of how we ended up with a brain that burns 20% of our metabolic energy within natural evolution, that requires a positive energy gain for all increases in brain capacity. Our small-brained ancestors used stone tools and fire, which didn't require much brainpower. Other primates handle large social systems and use tools, making these areas that don't require much brain power.
Hypothesis: The driving force for brain evolution occurred when someone noted that not all rocks are equal, and deposits of obsidian were rare and far superior. We had to break with the normal primate behavior of killing the guy who brought in better rock and stealing his rock. Someone gave him food and bobbles to go back and get more rocks. The advent of "specialization and trade" provided a huge individual advantage to someone smarter and who could remember not just his own tribe but also all the trading partners, those who could be trusted, and those who would cheat him. Without writing, the jump in complexity is huge, with the energy/nutrition payoff of super-sharp cutting tools and salt from trade would justify more energy for a better brain. Trade transit times were walking, not jets. The Bronze Age required massive trade, but once we invented writing, the driving force for a larger brain decreased. Hence, there has been a lack of strong selection in recent centuries.
This was excellent. But the claim that intelligence is not valued in the Hebrew Bible or the works of Homer is so insanely wrong that it almost makes me second guess Reich's reliability and credibility. (It doesn't actually, particularly given how far apart that point is from the area of his expertise, but it makes one wonder.) I hope that he has arrived at that view from vibes or secondary sources, and not that he actually read any of those texts and took that conclusion away.
A fascinating discussion to be sure. I do have one question: are variations in gene expression, as opposed to frequency of alleles, identified in these ancient DNA analyses?
Terrific interview. What I found interesting was Darwin’s theory held up with completely different data from that used to develop natural selection, and developed findings Darwin could not have predicted. Allele changes are the new finch beaks and mollusks.
> He and collaborator Ali Akbari just published a paper that overturns a long-standing consensus about human evolution — that natural selection has been dormant in our species since the agricultural revolution
Citation needed! Sounds highly implausible! So I asked ChatGPT "Is there a consensus that natural selection has been dormant in our species since the agricultural revolution?" It said:
> No. There is no scientific consensus that natural selection in humans became “dormant” after the agricultural revolution. In fact, the mainstream view in evolutionary biology is almost the opposite: humans have continued evolving, and in some cases may even have experienced new selective pressures after agriculture emerged.
Outstanding! Fascinating and brilliant! Kudos to both participants.
Question: Is there not an ambiguity in the “ancestor-descendant” terminology? In the common, straightforward sense, your “ancestors” are your parents, their parents, their parents, etc.; you are “descended” from all the people (and proto-people) in your family tree. But in another sense, we might say you are “descended” only from those from whom you have derived at least one gene (or other significant bit of genetic material). This will probably (I haven’t done the calculation) be a small minority of those in your family tree: given the small total number of your genes, you inherited nothing from most of your ancestors-in-the-first-sense who were living as recently as the high middle ages. (Serious inbreeding would modify this result). Do we not think of our real ancestors as those from whom we have derived our genes? This would be using ‘ancestor’ in my second sense.
In trying to answer the question of how we ended up with a brain that burns 20% of our metabolic energy within natural evolution, that requires a positive energy gain for all increases in brain capacity. Our small-brained ancestors used stone tools and fire, which didn't require much brainpower. Other primates handle large social systems and use tools, making these areas that don't require much brain power.
Hypothesis: The driving force for brain evolution occurred when someone noted that not all rocks are equal, and deposits of obsidian were rare and far superior. We had to break with the normal primate behavior of killing the guy who brought in better rock and stealing his rock. Someone gave him food and bobbles to go back and get more rocks. The advent of "specialization and trade" provided a huge individual advantage to someone smarter and who could remember not just his own tribe but also all the trading partners, those who could be trusted, and those who would cheat him. Without writing, the jump in complexity is huge, with the energy/nutrition payoff of super-sharp cutting tools and salt from trade would justify more energy for a better brain. Trade transit times were walking, not jets. The Bronze Age required massive trade, but once we invented writing, the driving force for a larger brain decreased. Hence, there has been a lack of strong selection in recent centuries.
This was excellent. But the claim that intelligence is not valued in the Hebrew Bible or the works of Homer is so insanely wrong that it almost makes me second guess Reich's reliability and credibility. (It doesn't actually, particularly given how far apart that point is from the area of his expertise, but it makes one wonder.) I hope that he has arrived at that view from vibes or secondary sources, and not that he actually read any of those texts and took that conclusion away.
A fascinating discussion to be sure. I do have one question: are variations in gene expression, as opposed to frequency of alleles, identified in these ancient DNA analyses?
Terrific interview. What I found interesting was Darwin’s theory held up with completely different data from that used to develop natural selection, and developed findings Darwin could not have predicted. Allele changes are the new finch beaks and mollusks.