The Wild Life of Our Bodies

It is certainly true that enormous changes in human ecology have occurred in a very short time—ones that sharply contradict our evolutionary and environmental history. Cities, infrastructure, fast food, digitalization, and light pollution have produced a world that is purely a human creation and devoid of naturalistic elements. Various functional systems in the human body, such as digestion and immunity, are, in part, products of specific threats in the environment (e.g., predators or microorganisms) that challenged our existence millennia ago but were successfully negated in enough cases for us to continue living today. As result, these systems may find their niche not in today’s developed world but in the world of prehistory.

While one cannot deny the potential for serious consequences caused by an increasingly artificial world, Rob Dunn’s—as he puts it—idyllic portrayal of human ancestry in the introductory portions of The Wild Life of Our Bodies seems to speak more to the author’s own sentimental and nostalgic image for prehistory than to an accurate display of a period that he admits was ridden with predation, disease, suffering, and mercilessness unseen by most of today’s people. I will not deny the benefits of frequent exposure to the natural elements of our planet. However, an important characteristic of humans may negate Dunn’s assertions about the need for a re-infusion of naturalistic elements into metropolitan life. This characteristic is adaptability, both neurologically and genetically.

Advances in neuroscience, biological psychology, and genetics reveal a high level of adaptability in human behavior and physiology through neural plasticity (“plastic” meaning “easily shaped or molded”) and variability in gene expression. While classical evolutionary processes occur over millions of years, the human brain—and consequently the physiological functions controlled by it—updates its structure in real-time in response to environmental input. One might even say this is a main function of a nervous system: to actively adapt to the environment without the waiting period of reproduction, mutation, etc. Moreover, research in epigenetics (“epi-” meaning “above” or “around,” implying a form of genetic control exterior to DNA) has revealed that gene expression is not a fixed phenomenon determined at conception, but instead—though to a much lesser extent than the brain—is responsive to environmental conditions. Therefore, our bodies and brains may have a surprising ability to adapt to the seemingly inorganic aspects of developed civilizations—perhaps without facing the dire consequences foreshadowed by Dunn.

Furthermore, while the genome of a developing embryo “expects” a child to be born into a world similar to the one of prehistory, one must not forget the degree to which the brains of newborn infants are “blank slates,” uncontaminated by experience and learning. The initial experiences of an infant—whether they are those of a dense forest or a McDonald’s—become, for all intents, his or her “natural” environment. Environmental stimuli, working in an interdependent relationship with one’s genome, carve the early architecture of an infant’s brain. In other words, physiological response tendencies (i.e., how one’s brain or body responds to various environmental stimuli) and gene expression are in a perpetual feedback loop with the environment (via the sensory systems and the brain) that allow it to adjust accordingly to the world the infant occupies. The result is a developed adult who has, at least in part, adapted to the world of today – possibly mitigating the risks alluded to by Dunn.

Finally, while the incidences of certain problems, like autism, are on the rise in today’s culture, it is important to realize that any system is going to have its problems—but the ones that arise will be specific to that system. Human systems in prehistory had problems such as predation and dysentery; today’s systems have autism and diabetes. Pick your poison.

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3 Responses to The Wild Life of Our Bodies

  1. Great post, technical but not dense.

    Regarding the plasticity of the brain, I’m curious where you’re getting that information, do you have a source? When you say the brain updates itself, how do you mean? The brain can certainly grow new neurons and the wiring (for lack of a better term) differs from person to person, but as an organ it is essentially the same across human beings. If you’re talking about learning and storing experiences as memories wouldn’t that fall under the argument you later pose of the blank slate?

    Speaking of the blank slate, essentially you’re discussing nature vs. nurture. The nurture might allow people today to adapt to their environment (by the way great point about adaptability), but do you think that would be able to cover all circumstances? For instance, we can build technology to clean air pollution, but at a certain point (Beijing, Shanghai, etc) we can’t keep up with the environment no matter how adaptable we are.

      tanneraustin says:

      I don’t have a source per se, but as a psychology a major, I can say a major focus of certain courses is on neuroplasticity. There are many sources I’m sure, as I am confident this is an important area of research. Neuroplasticity is simply the brain’s ability to form and break connections. But what is surprising is the extent to which it can do it. For instance, one study has shown 27 minutes of meditation per day for eight weeks produced significant reductions in the density of gray matter in the amygdala, the fear center of the brain (source below). I chose the word “update” because it reflects that our brains change their connections in real-time in response to the environment. Structures in our brains don’t become new structures in our lifetimes, but they do change–and they change physically.

      I agree that adaptability is only effective to an extent. Our genes are still basically prehistoric. My main point is that Dunn may be exaggerating the need for us to surround ourselves with things from our natural pasts. We can adjust, but only so far.

      http://www.sciencedaily.com/releases/2011/01/110121144007.htm

  2. I agree with Kelly – the technical information in this post is presented in a way that is accessible to us non-specialists. Thank you! I am going to be very interested to hear what you think about Dunn’s later chapters (about the legacy of the fight-flight response). I do not think he is nostalgic about the distant past or romanticizes it as somehow “better” than contemporary society. His main point supports your discussion here of neuro-plasticity, which is that our biological beings are both products of very old relationships with our environment and other species, and the contemporary context into which we are born. So both nature and nurture have historic and biological components. Neither is a given.
    We should also keep in mind the other issue both Dunn and Stiner / Feeley-Harnick address, which is that our humanity is intimately and intricately bound up with other creatures.

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