When was the last time you needed to do research for an upcoming paper? I bet you started by looking for information online. How did you go about your search? Which websites looked promising? Which ones did not entice you to click past the home page? Once you found one you thought might be useful, how much time did you spend searching for information? At what point did you decide to leave that site and move on? I would wager money that you never once thought your behavior had anything to do with human evolution, but it does.
Although we may not often stop to think about it, our evolutionary past is reflected in many aspects of modern life. The ways we “forage” for information on the internet mimics the ways we once foraged for food during our several-million-year history as hunter-gatherers (Chin et al. 2015). Humans are visual hunters (Lieberman 2006). We practice optimal foraging strategy, meaning we make decisions based on energy return for investment (McElroy and Townsend 2009). When we search for information online, we locate a “patch,” in this case a website or research article, then quickly scan the contents to discern how much of it is useful to us. Like our hominin ancestors, we spend more time in “patches” with abundant resources and abandon sites quickly once we have exhausted the available goods. As with internet searches, our evolutionary past is also reflected in the kinds of landscapes we find appealing, the foods that taste good to us, why we break a sweat at the gym, and why we have to go to the gym at all (Bogin 1991; Dutton 2009; Lieberman 2015). Many of the health problems facing humans in the 21st century also have their beginnings in the millions of years we roamed the earth as foragers.
This chapter addresses contemporary health issues from an evolutionary perspective. It begins with a review of diet, activity patterns, and causes of morbidity (sickness) and mortality (death) among our preagricultural ancestors, which form the foundation for the ways our bodies function today. This is followed by a brief review of the health consequences of the transition to agriculture (see “Cultural Effects of Agriculture” in Chapter 12 for more detail), marking the first of several major epidemiological transitions (changes in disease patterns) experienced by humankind. It then addresses health conditions affecting modern, industrialized societies, including obesity, diabetes, heart disease, cancer, and the effect of stress on health. The environments in which we now live and the choices we make put a strain on biological systems that came about in response to selective pressures in our past, meaning the ways our bodies evolved are, in many ways, a mismatch for the conditions of modern life