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"Kwa-speaking agricultural
groups of West Africa, who for at least several millennia have
cleared forests to create fields in which to plant crops (Posnansky
1969). Tree removal had the unintended consequence
of increasing the amount of standing water after heavy rainfalls,
which led to a rapid increase in mosquitoes such as
Anopheles gambiae, which need sunlit pools in which to breed
" (Livingstone 1958)

[ ... ]

"Today, there are several hundred million clinical
cases of malaria worldwide and roughly 800,000 deaths each
year (Kappe et al. 2010), the majority of them in sub-Saharan
Africa. **With respect to the Kwa, this is a classic case of ecological
inheritance, with generations of descendants being affected
by the upstream activities of their forest-clearing ancestors
many generations before

[ ... ]

"But similar to what occurred with Neolithic dairying, this
culturally induced disruption of the ecosystem had recursive
effects on the human genotype.

"...there is a variation in the beta polypeptide
chain, which results in the polymerization of the hemoglobin,
causing some red blood cells to become stiff and
take on a sickle shape. This sickling provides some protection
against malaria because sickled cells are recognized by the
spleen as they flow through and are removed, thus flushing
the parasite with them. *
The recursive effect on humans is that
the variant (HbS) form confers heightened protection against
malaria in heterozygotes*."

"Decades of yam cultivation intensified
natural selection on the human hemoglobin (HbS) allele,
causing it to increase in frequency.
The fact that neighboring
Kwa-speakers with different agricultural practices do
not show the same increase in (HbS) supports the conclusion
that culture—clearing fields for yam cultivation—is driving
human genetic evolution
." (Durham 1991).

Added by Alex Singh
Updated 2 hours ago

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