As this thread is also about the oral microbiome, I post this here as I can't find a more appropriate thread.
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"The evolution and changing ecology of the African hominid oral microbiome", May 2021, featuring names like Johannes Krause, using the oral microbiome of hunter-gatherers Sapiens (n=20) and Neanderthals (n=17) since 100,000 years , concludes:
1) "the Upper Paleolithic individual from El Mirón in Iberia (18.6 ka) clusters with Neanderthals, rather than with other Pleistocene hunter-gatherers of the African Later Stone Age or more recent Holocene-era European or African populations. Recently published human genomic data including this individual has revealed that its associated genetic ancestry component was largely displaced across Europe after 14 ka during postglacial warming. Turning to our low-coverage metagenomic datasets, we assessed additional European Upper Paleolithic and Mesolithic groups and found that they show a similar pattern (albeit at lower resolution), with the oral taxa of individuals dated to before 14 ka mostly falling with Neanderthals and those after 14 ka mostly clustering with present-day modern humans. This pattern suggests that the reconstructed oral bacterial genomes from El Mirón reflect a standing microbial diversity in Homo that was present in Europe during the Middle and Upper Paleolithic, but which was later replaced following subsequent migrations of modern human populations from elsewhere."
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Is this change in the Sapiens oral microbiome 14,000 years ago due to the fact that, at that time, the diet of glacial Europe, based on the meat of the large herds of steppe herbivores, was replaced by post-glacial small game and forest plants, warmer weather and less cooked foods? I ask this, because in order to have the same oral microbiome as the Neanderthals, the first European Sapiens, coexisted intimately with them (for instance, kissing on the mouth, sharing a deer leg...) before they replaced them, and the waves of Sapiens that followed also coexisted intimately with the previous populations before replacing them. I know little about paleogenetics but this wave after 14,000 years ago and the one that followed, the Neolithic, also coexisted at least in the Iberian Peninsula, with the populations prior to 14,000 years ago, according to the study that includes the same individual from El Mirón and is authored by the same Johannes Krause: Current Biology, Villalba-Mouco et al.: "Survival of Late Pleistocene Hunter-gatherer ancestry in the Iberian Peninsula"
https://www.cell.com/current-biology/fulltext/S0960-9822(19)30145-9
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2) "starch-rich foods [tubers, wild cereals, pods...], possibly modified by cooking first became important more than 600 ka".
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A few million years ago, as the climate became drier, the fruits we fed on became more compact (first in pods, later in wild cereal seeds...) and their content became starch. Our teeth have adapted to grinding this seeds and we have invented tools capable of digging up tubers or chop and hammer these hard foods. For a frugivore who hail from the forest, as we were a few million years ago, this starch-rich foods are the most affordable foods on the savannah.
This conclusion of the authors of this study is uncomfortable for those who defend the importance of carnivorism in human evolution, very much in vogue with paleo diets nowadays.