High-fidelity cultural transmission, rather than brute intelligence, is the secret of
our species’ success, or so many cultural evolutionists claim. It has been selected
because it ensures the spread, stability and longevity of beneficial cultural traditions,
and it supports cumulative cultural change. To play these roles, however, fidelity must
be a causally-efficient property of cultural transmission. This is where the grain problem
comes in and challenges the explanatory potency of fidelity. Assessing the degree of
fidelity of any episode or mechanism of cultural transmission always depends upon an
investigator’s choice of grain of analysis at which cultural traditions are being studied.
The fidelity of cultural transmission then appears to be relative to the granularity at
which one approaches cultural variation, and since there is a multiplicity of grains of
description by which the same tradition can be studied, there results a multiplicity of
measures of fidelity for a same event or mechanism of cultural transmission. If this is
correct, because fidelity is always relative to the grain of analysis dictated by the local
and specific research interests of the investigator, then there seems to be no fact of the
matter as to whether cultural transmission is faithful or not, independently from a
researcher’s framework of analysis. The aims of this talk are to offer a conceptual
clarification of the grain problem in cultural evolution, to assess its causes, to unpack
its epistemological implications, and to examine its reach and consequences for a
science of cultural evolution.