Paleo-Deficit Disorder: How a Deficiency of Ancestral Influences is Making Us Sick


Figure from “Natural environments, ancestral diets, and microbial ecology: is there a modern “paleo-deficit disorder”? Part II.”  by Alan C Logan, Martin A Katzman, and Vicent Balanzá-Martínez. Creative Commons licence.

I rarely put up short posts on this blog, as I generally like to pick a topic and do a fairly comprehensive article on that subject before I move on. However, sometimes I come across a research paper, article, or video that is so good that it deserves a post of its own. The recently published review paper titled “Natural environments, ancestral diets, and microbial ecology: is there a modern “paleo-deficit disorder”?” by one of my favorite researchers, Alan C Logan, and colleagues definitely fits the bill.

The main reason I wanted to put up an own post on this paper is that it touches on a lot of the things I talk about on this site; in particular how changes in the human diet over the past millenia have affected our health and how inadequate exposure to microorganisms can cause chronic low-grade inflammation and disease.

The implications of being disconnected from the natural environment

As you know if you’ve been following this blog, one of the main themes of Darwinian Medicine is that many of the health problems that plague us in contemporary societies arise because our bodies are inadequately adapted for modern environments. As the Wikipedia page on evolutionary medicine notes: “Humans evolved to live as simple hunter-gatherers in small tribal bands, a very different way of life and environment compared to that faced by contemporary humans” (1).

In the modern world most of us subject our bodies to stimuli that fall in the category of being too much, too little, or too new. For example, we spend too much time staring at a computer screen, exercise too little, and eat evolutionarily novel foods. As you can see from the figure/picture above, the authors of the review paper on the paleo-deficit disorder focus primarily on how too little exposure to certain stimuli affect our health.

The great thing about this paper is that it doesn’t only focus on the most obvious problems with the modern lifestyle (e.g., insufficient physical activity, poor diet choices), but also on areas that tend to receive less attention, such as how a disconnection from the natural environment is affecting our subjective well-being. Instead of discussing this in length, which I’ve done many times before, I wanted to highlight two quotes from the paper that summarize what a “paleo-deficit disorder” really is:

The health problems associated with rapid urbanization are profound, most notably the chronic non-communicable diseases (NCDs)—e.g., mental health disorders, and obesity and its correlates of type II diabetes, metabolic syndrome, and cardiovascular disease [6-13]. Urbanization, particularly in deprived areas, may drive changes in behavior that contribute to NCD risk—low physical activity, compromised sleep, and unhealthy dietary choices [14-17]. The progressive movement away from less sanitized traditional lifestyles has also altered the diversity of microbial contact [18]. Much has been written regarding environmental variables, including Westernized dietary patterns and increasing microbial sanitization, and their association with marked increases in allergic and autoimmune conditions in developed nations—as much as tenfold higher vs. developing nations. (2)

What are the psychological consequences of a collective deficiency of ancestral influences in the modern landscape? What is the fallout from more time indoors and less experience with variables associated with natural environments or parts thereof? The “less” we refer to is broad—it ranges from the diversity of birdsong and non-pathogenic microbes to the blue spectrum of daylight and varieties of vegetation around a residence. It includes less dietary diversity via loss of traditional foods and the diminishing phytochemicals within them. In the context of evolutionary experience, we consider these to be modern deficits.

We wonder could this collective deficit manifest in a “disorder,” a sort of paleo-deficit disorder, that while not pathological per se, taps into unrealized quality of life, empathy, perspective taking, low-grade anxiety, psychological distress, resiliency, and negative mental outlook? Could this deficit accelerate an individual toward the checkmarks required for medicalized diagnoses? Might the collective deficit in “Paleolithic experiences” compromise an individual’s ability to maintain optimal emotional health and by extension, prevent optimal health of neighborhoods, cities, societies, and nations, especially those undergoing rapid urbanization? (3)

The whole paper can be access for free here (part 1) and here (part 2). It’s quite long, but definitely worth the read. Also, if you want to dig deeper into this area of research I recommend checking out the publications of Dr. Alan C. Logan.

Do you have any thoughts on how we as a society can reconnect with nature and overcome our collective paleo-deficit disorder? Let me know in the comment section below.


  1. Thank you for sharing this report…a very thorough analysis of the ways in which urbanization impacts our lives from many angles from psychological, physical, mental, social emotional to environmental, etc.

    • Definitely. It’s one of the most comprehensive research papers on ancestral health and evolutionary mismatches that’s out there. The authors manage to bring together “all” of the important research in this area.

  2. Jennifer says:

    Great article, and a very impressive list of books by Dr. Logan. Thanks!


  1. […] literature that all of us in the modern, industrialized world suffer from a so-called “Paleo-Deficit Disorder“. This disorder, which taps into several aspects of our health, doesn’t just encompass […]

  2. […] into many other aspects of the gene-environment mismatch we face in the modern world. I devoted a short post to this research paper a while back. It’s quite long, but definitely worth a […]

  3. […] singing birds, and rivers with concrete pavements, huge office buildings, and vehicles. This is problematic for a number of reasons, one of which being that we’ve lost contact with some microorganisms that co-evolved with […]

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