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The Ādam Paradox Hypothesis 77
Demography and the Cultural Ratchet
A third pillar emphasizes population dynamics. Small,
scattered groups are prone to losing complex traditions
through drift; their teaching chains are short, and innovations
vanish when individuals die. By contrast, large,
interconnected populations can preserve and ratchet culture
cumulatively.
Powell, Shennan, and Thomas (2009) argue that once
populations reached a critical density, traditions could be
transmitted more reliably and built upon. This, they suggest,
explains why early ornaments at Qafzeh and Skhul (~100kya)
or engravings at Howiesons Poort (~65kya) flickered out,
while after 70kya, symbolic repertoires stabilized and spread.
Claim. Small, scattered populations struggle to maintain
complex traditions (loss through drift). When group size and
connectivity increase, teaching chains lengthen, error-
correction improves, and traditions ratchet cumulatively
(Powell, Shennan, & Thomas, 2009).
Population scale and
Case studies / anchors.
connectivity are key
to persistence (not
Qafzeh/Skhul (~120–90kya): marine shell beads found far
necessarily to origin)
inland; ornaments signal social identity but do not persist
of symbolic
regionally, consistent with small, vulnerable networks.
repertoires.
Howiesons Poort (~65–60kya): backed microliths, engraved
ostrich eggshell; sophistication appears, wanes, returns —
vulnerable to drift in limited populations.
Post-70kya dispersals: rapid spread of beads, ochres,
ornaments, implying larger metapopulations able to preserve
and copy reliably.
Takeaway. Population scale and connectivity are key to
persistence (not necessarily to origin) of symbolic repertoires.