Page 493 - Cultures and Organizations

458 IMPLICATIONS

marize, selection takes place at the bottom of the fi tness scale, at the
top, and randomly. Given a large enough population, natural selection
will preserve any variants that are not harmful to reproductive capac-
ity. In a large population this means that many variants will occur that
have no obvious effects but that constitute a potential for adaptation to
possible new circumstances.
3. Evolution is path dependent. It might seem that evolution could do
anything, but this is a mistaken point of view. Evolution is always lim-
ited by circumstances, notably by its own history. And there is no turn-
ing back. Human evolution shows this clearly. People frequently suffer
from aches in their lower vertebrae, hips, and knees because these
joints have become more heavily taxed since our ancestors started to
walk upright, perhaps as an adaptation to moving in tall grass. Once
upright, humans have continued to walk on two legs even in forest

habitats, because of the side benefits of freeing the hands. 34
4. Evolution uses many replicators. Darwin knew nothing about
genes, but he was very insightful about evolution. The discovery of
DNA molecules as the carriers of genes a century later proved him to
be in the right. Though genes are an eminently successful replicator
for evolution on our planet, they are by no means the only one, and
there is no sense in which nongenetic evolution is less evolutionary
than genetic evolution. The evolution of human civilizations is only
loosely coupled to genes. Many kinds of knowledge reproduce them-
selves through the transmission of skills through teaching, and as we
have seen, cultural values are also transmitted to new generations. So,
the society, as a unit of transmission of knowledge and of culture, has
also become a powerful replicator among humans. The idea that evo-
lution can simultaneously take place using different replicators—for

instance, using genes at the level of the individual and using knowl-
edge and values at the level of society—is called multilevel selection.
We are now about as much in the dark about society-level evolution
as Darwin was about genes when he wrote On the Origin of Species:
observation has provided us with credible arguments in favor of cul-
tural evolution of societies, but we do not know just how it happens.
In other words, we have no sound idea about the precise nature of the
replicators, what is called the proximate mechanisms of evolution. The
discussion about how culture replicates itself, and how it is selected, is
35
still open. Further, while the delimitation of an individual is clear, it