In 2012, after being home to various classes of primates for more than 100 years, the renowned Monkey House at the Bronx Zoo closed down. The zoo's current primate inhabitants reside in spaces designed to match their natural habitats. The shift is part of a broader movement in zoos around the world, based on the highly reasonable idea that all species have evolved to fit particular environmental conditions. Such features that typify an organism's ancestral conditions characterize its Environment of Evolutionary Adaptedness or EEA (Bowlby, 1969). Housing a monkey, whose ancestors go millions of years deep into specific African jungle environments, in a small cage in the zoo of a large city was simply evolutionarily misguidedand arguably cruel.

Animals essentially need to have many key features of their ancestral environments in their current conditionsbecause their bodies and minds are the result of evolutionary processes that took place under these specific conditions. In an evolutionarily novel and unnatural environment, solid research shows that various primates will demonstrate signs of physiological and psychological stress (see Harlow & Suomi, 1971).

This idea critically relates to the nature of being human in modern times. If you live in a modern, Westernized part of the world—as you almost certainly do if you’re reading this—then you are, in many ways, metaphorically living in a cage in a zoo.

A key principle of evolutionary psychology (see Geher, 2014) is the notion that modern humans in Westernized societies experience important instances of evolutionary mismatch. Understanding this is essential in understanding much of what it means to be human today.

Here is a list of 10 ways that modern, Westernized humans like you and me are, in the words of Kurt Vonnegut, living “in the Monkey House”:

10. You are surrounded in your day-to-day life by a higher proportion of strangers than would ever have been true of our pre-agrarian hominid ancestors.

9. You run into a higher total number of people each day than our pre-agrarian hominid ancestors ever would have.

8. You have the option of spending 90 percent of your waking hours sitting at a deskand you often exercise this option.

7. Your extended family includes people dispersed across hundreds or thousands of miles (think New York and Florida).

6. You have been exposed to more images of violence than ever would have been possible for pre-agrarian hominids.

5. You were likely educated in an age-stratified systemspending each of several years in a group comprised of about 25 others who matched you in agebeing taught in a classroom environment by a few specially designated “teachers.” You likely spent a lot of time sitting behind desks in the process.

4. You are exposed regularly to politics at a global scaleoften discussing or being involved in issues that potentially pertain to thousands, millions, or even billions of other humans.

3. You were raised in some variant of a nuclear familywith less assistance from aunts, uncles, older cousins, and grandparents, than would have been typical of our nomadic ancestors.

2. You spend a great deal of time interacting with “screens” and “devices”having the evolutionarily unprecedented possibility of almost never having to be bored at all.

1. You can eat an entire diet of processed foodsand you live in a world in which processed foods are cheaper and more accessible than natural foods.

This list is certainly incomplete and, at best, preliminarythere are undoubtedly many other worthy contenders. That said, I’m hopeful that the list can help open the eyes of those interested in human psychology to the importance of evolutionary mismatch in understanding all aspects of who we are.

Welcome to the Monkey House.

References: Bowlby, J. (1969). Attachment and loss. Vol. 1. Attachment. New York: Basic Books.


Harlow, H.F., & Suomi, S. J. (1971). Social Recovery by Isolation-Reared Monkeys, Proceedings of the National Academy of Science of the United States of America,  68,1534-1538.

Vonnegut, K. (1968). Welcome to the Monkey House. New York: Delacorte Press.

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