For example, people will copy the idea of a ghost with lowfidelity (missing or
distorting details and adding new ones), but the idea will remain relatively
stable across generations because the idea of a ghost is constrained by innate
psychological structures (cf. Boyer, 2002; and section 2.2.4). However, the
fact that cultural bits are shaped by psychological biases does not have to
exclude the presence of evolutionary processes. For example, particular rep-
resentations of ghosts, tales about ghosts, or practices related to ghosts and
spirits can take different forms so that evolution can shape them. We will
come back to the problem of attraction and selection later in this chapter.
Although the exact nature of memes has not yet been clarified, it is clear that
we inherit cultural traits from our ancestors that can vary and influence the
proportions in which they are passed on. In this sense we can speak of the
natural selection of cultural traits, even if the mechanisms by which this occurs
are not yet fully understood. For example, making a better tool could contrib-
ute to the reproductive success of one of our human ancestors, who then
passed on his or her technological know-how to his or her children. Ethno-
graphic evidence shows that in pre-industrial societies the transmission of
most knowledge took place within families, mostly from parents to their
children of the respective sex (Shennan, 2002, pp. 38–42). However, cultural
transmission has also followed more complicated routes, and this is especially
true in our modern, post-industrial, societies, where people acquire vastly
more memes from other sources than from their parents. This already suggests
that cultural evolution works differently from genetic evolution, even though
both of them comply with our definition given above. Understanding the exact
mechanisms of cultural evolution will be probably as revelatory for the study
of culture as the discovery of genes was for the theory of genetic evolution
(cf. Shennan, 2002, pp. 56–64).
We have briefly mentioned above that genetic evolution is modulated by
another channel of inheritance, called epigenetic information. In a narrow
sense,“[e]pigenetics refers to how genetic material is activated or deactivated—
that is, expressed—in different contexts and situations”(Moore, 2015, p. 14).
For example, domestic violence will leave lasting effects on a fetus’s epigenetic
information and change the expression of the genes as the child develops later
(p. 100). The accumulation of such influences extends into childhood and
even adulthood. Surprisingly, epigenetic changes in the organism can be
passed to subsequent generations, a phenomenon calledepigenetic inheritance
(pp. 145–66). In recent years, new insights about epigenetic inheritance have
been pouring in that might lead biologists to rethink the concept of Darwinian
evolution (Klironomos et al., 2013; Dias et al., 2014; Skinner, 2015).^3
(^3) Epigenetic mechanisms can interact with genetic inheritance. For example, epigenetic
factors influence the mutation of genes, resulting in non-random mutations. If mutations on a
Evolution 27