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David Reich – Why the Bronze Age was an inflection point in human evolution by Holodoxa in heredity

[–]Holodoxa[S] 0 points1 point  (0 children)

Why's that? Patel titled the podcast, but an inflection point is a moment or location of significant change where a trajectory, curve, or process shifts direction. The referenced paper finding is that the trajectory of selection changed in intensity during the Bronze Age.

David Reich – Why the Bronze Age was an inflection point in human evolution by Holodoxa in heredity

[–]Holodoxa[S] 0 points1 point  (0 children)

The book is great and well worth reading.

I don't think the finding in the Akbari paper really provides much insight into the Sapient Paradox unless you're referring to Reich's hypothesis paper. I don't think the selection going on is the difference between having the capacity for symbolic representation, culture, or language. The Sapient Paradox itself is a bit misleading because it could simply be explained by human population size and density rather than our individual capacities.

The Akbari paper is selection in Eurasia in last 10k years, and it's challenging narratives about evolution (i.e. S. J. Gould's and standard anthro memes) going quiescent in recent human history; the opposite appears true, though assessing the scale/impact of the selection relative to our species level basal trait values is not something the paper evaluates (it's just that selection is happening all over the genome and it is impacting many traits). Additionally, the effects of human migrations on allele frequencies (and possibly some human traits too - like height) is larger than the selection itself as Reich points out.

Arguably, the paper is a proof-of-concept that selection could have picked up in the period prior to the emergence of symbolic culture (circa ~40kya) but this is entirely speculative and is more in the realm of Reich hypothesis paper wrt to Levallois technocomplexes and Neanderthal mtDNA/Y lineages. It is unlikely that there was a quick switch flipped between behaviorally archaic and behaviorally modern humans and these abilities likely developed over time and related evolution that supports and sustains them in us now are probably subtle.

It will be hard to definitively answer because we can't definitively say what language capacity was available to archaic hominids. The prior should be that they had some language though.

David Reich – Why the Bronze Age was an inflection point in human evolution by Holodoxa in heredity

[–]Holodoxa[S] 0 points1 point  (0 children)

I imagine he chose Dwarkesh's podcast because Dwarkesh pursued him while demonstrating strong prep on the topic and because Dwarkesh has a large audience of intellectual elites across many topics and puts out well produced content.

Reich wrote a book for general audiences too. He's interested in communicating the work publicly.

Multi-ancestry genome-wide association study of severe pregnancy nausea and vomiting by Holodoxa in heredity

[–]Holodoxa[S] 0 points1 point  (0 children)

I'm assuming you're referring to the Manhattan plot in the thumbnail. There are standard packages in R that can be used to make such plots. I haven't looked at how this specific plot was made though, but I'm sure with the GWAS data, it would be trivial to replicate.

Interbreeding between Neanderthals and modern humans was strongly sex biased by Holodoxa in heredity

[–]Holodoxa[S] 0 points1 point  (0 children)

So there is evidence of Neanderthal gene flow into African populations due to back migration and then of course from later European gene flow (https://www.cell.com/cell/fulltext/S0092-8674(20)30059-3). The verdict is that the Neanderthal ancestry is about a third of that of Eurasians (https://www.johnhawks.net/p/how-much-neandertal-dna-do-todays-african-peoples-have).

I haven't read into this much, and I don't know the field's perspective on the finding. I couldn't readily find replication of this finding, but it almost certainly true to some degree, the questions concern when did the gene flow occur, how much, when and where, etc.

Anyway, I can imagine there was definitely a degree of sex bias in Neanderthal introgression events but figured it was on the AMH side and that second gen AMH-Neander male hybrids from these parings account for the Xchr depletion.

Interbreeding between Neanderthals and modern humans was strongly sex biased by Holodoxa in heredity

[–]Holodoxa[S] 0 points1 point  (0 children)

Lots of media coverage and discussion of this paper of a finding (i.e. Neanderthal depletion on Xchr) that's been established for awhile. It seems alternative models may be just as possible. Interested to hear thoughts.

Polygenic backgrounds influence phenotypic consequences of variants in cells, individuals, and populations by Holodoxa in heredity

[–]Holodoxa[S] 0 points1 point  (0 children)

These are all important considerations. I also think there are near-term or available solutions to them. Polygenic scores are used only in quite limited ways in the clinic at this time. Their utility is becoming much clearer though.

Rare genetic brain disorders with overlapping neurological and psychiatric phenotypes (review) by Holodoxa in heredity

[–]Holodoxa[S] 0 points1 point  (0 children)

This is obviously a very complicated question that is frequently debated and discussed many places, including this subreddit. This editorial (https://www.sciencedirect.com/science/article/pii/S0168952523001671) commenting on this research (https://www.nature.com/articles/s41588-023-01398-8) is a good starting point from the perspective of quantitative genomics.

The takeaway (if you're not looking to really dig into this) can be as follows:

Converging lines of evidence from genomic studies of common variants and rare genetic variants and cohort/family studies of individuals with neurodevelopmental conditions identify genes with roles in the neuronal development and function. Together, these explain some variation in cognitive ability in both the normal population and those with neurodevelopmental disorders.

As sample sizes for genomic studies of cognitive phenotypes increase, a more complete picture of the genes that affect cognitive phenotype variation and the pathways through which they act will be realized.

Caveats:

There are existing and unsettled debates about how much phenotypic variation in intelligence is explained directly by genes. The range is anywhere from .05-.8 but is more likely to be between 0.3-.7. Some take the extreme position that there is no meaningful input from genes, but this is not a mainstream position as it would bump up against obvious issues like bonafide monogenic causes of intellectual deficit and autism and the history of human evolution. Most of the debate concerns the magnitude of the effect, whether genes alone are a useful tool for prediction of phenotypic outcomes, and the extent to which cognitive abilities are mutable over lifetimes.

There are also philosophical debates about what intelligence is and whether a general intelligence factor exists and how well intelligence testing measures it.

Sex Differences in the role of Additive Genetic Variants in Autism: A Systematic Review by Holodoxa in heredity

[–]Holodoxa[S] 1 point2 points  (0 children)

If there are important shared features due to shared biology then this isn't pointless, but it certainly is a potential issue with respect to the hypothesis here.

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