evolution and the modern environment, the authors ofThe Evolution of
Obesityexplain:
The current epidemic of obesity thus results from the interaction of our environment
with past adaptations that are now inappropriate given the modern milieu. Our biology
and our modern lifestyle no longer match when it comes to weight homeostasis.
Obesity leads to pathology, and can even be perceived as pathology, but its causes may
be normative, evolved adaptive responses to a past world of high energy expenditure
and uncertain and variable food intake. (Power & Schulkin, 2009,p. 40)^15Following up on this, they discuss modern society as an obesogenic
environment under the title “Evolution, Adaptation, and the Perils of
Modern Life” (Power & Schulkin, 2009,pp. 111135):
The obesity epidemic that is in full swing in economically advantaged countries is just
beginning in the developing world. This gives us the chance to examine the features of
demographic, dietary, and cultural change that might underlie our species’ vulnerability
to obesity. (ibid., p. 111)In this context they find an “ironic aspect of human obesity...that it is fre-
quently associated with malnutrition, not only in the same population but
also in the same individual!” (idem). It is certainly awkward for the theory
of the obesogenic environment that obesity rates are as high or even higher
in countries such as Mexico or Egypt as they are in the United States, the
United Kingdom, or Germany. It is equally awkward that in societies
which are similarly “economically advantaged” obesity rates can be sharply
different. For instance, in the Netherlands 12% of the adult population
falls in the obesity category, while in the United Kingdom and Germany
this is about 25% and in the United States it is 35% (seehttp://www.iaso.
org/iotf/obesity).
A specific strand in the obesogenic explanation is the notion that “fat is
contagious.” Christakis and Fowler, for instance, developed this notion in
“The Spread of Obesity in a Large Social Network over 32 Years” ( 2007 ).
Inobesity prevention practices we find a similar notion applied when obese
parents have their obese children taken out of their custody. At a larger
scale this notion of social and cultural transmission of obesity is related to
fact that obesity is more prevalent among the lower social and economic
classes and among certain ethnic groups.
These familial, socioeconomic, and ethnic clusters could also be
explained along genetic lines. The importance of genes is generally recog-
nized, but usually accorded only a marginal role.^16 The CDC, for instance,
on its webpage devoted to “obesity and genetics” open with the following
statement:
126 ROEL PIETERMAN