The Universality of Darwinian Medicine

darwin-natural-history-museumIt’s often assumed that we humans are very dissimilar from other organisms with respects to the reasons as to why we are vulnerable to disease. A lot of people also take it for granted that the medical and biological principles that are important in the context of human health optimization differ from those that are important for optimizing the health of other organisms, seeing as that the anatomical and physiological configuration of members of our species, Homo sapiens sapiens, is unlike that of members of other species. By implication, this would also lead one to assume that medical principles are species-specific, seeing as each individual species on this planet has some unique features that distinguish it from other species.

I’d argue that it’s a mistake to make these assumptions and operate under the belief that the tools we need to possess to build a healthy human differ markedly from those that are needed to build a healthy insect, bird, fish, plant, or any other organism…

The wide reach of Darwinian medicine

It’s certainly true that we humans look and function very differently from for example cows, sheep, and bears. We also obviously look nothing like caterpillars, helminths, or other small animals. I don’t think anybody’s going to disagree that we have very different requirements, diet and lifestyle wise, than those creatures.

However, that doesn’t mean that the evolutionary and biological processes that shape our bodies and lives differ from those that shape the bodies and lives of other life forms. The fact is that all organisms on this planet are a part of the same evolutionary arms race and are, by implication, governed by the same biological principles. We all have to adapt to changing environments. Moreover, the faith of all of our genes lies in the hands of natural selection. This is very important to acknowledge, because it implies that there exists a unifying set of theories that should form the basis for all evolution-based medical prevention and care, and that Darwinian medicine encompasses the entire living world, not just the human part of it.

I would argue that it’s a mistake to solely focus our attention on Homo sapiens, or even hominins in general, when we set out on the mental quest of finding out why we get sick and what it takes to build a healthy human, seeing as doing so could lead us to overlook key things that we need to understand in order to achieve the ultimate objectives of our journey.

Darwinian theories bring order out of nature/life, which prior to Darwinian decoding looks chaotic and disorganized

All organisms, irrespective of the species they belong to, are evolutionarily programmed to survive and reproduce. This really goes without saying, seeing as only organisms that are concerned with survival and reproduction pass on their genes. Genes that contribute positively to organismal reproductive success in the prevailing environment live on, whereas genes that undermine organismal reproductive success don’t do so well, and may perhaps even go extinct.

Many natural phenomenons and behaviors of organisms can be understood on the basis of these facts. For example, the propensity of human females to seek out strong and dominant male partners is a relic of our evolutionary past, in which physically robusticity was important for survival and reproduction. A male back in the day that was fit and fairly strong had a better chance of providing his female partner(s) with food and protection than a weak and unfit man. Moreover, muscularity and physical robustness signal good health, which is important in terms of producing healthy offspring. Conversely, we men are attracted to voluptuous women because curviness signals that a woman is fertile and has stored up fat that may prove invaluable for providing a newborn with sufficient energy, particularly during times of scarcity.

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All organisms on this planet evolve via similar Darwinian processes; hence, the spotlight of Darwinian medicine illuminates the entire living world, not just the human part of it.

Darwinian theories are also invaluable for making sense of various phenomena related to health, nutrition, and medicine, as you undoubtedly know if you’re a regular reader of this site. I would actually go as far as to say that nothing in medicine makes sense except under Darwinian light. Human health is at the center of most of my articles on this site, which is natural, seeing as we are humans. Every now and then though, I’ve pointed out that many of the things I talk about are applicable to other organisms besides humans, so as to make it clear that Darwinian medicine has a wide reach.

Three commonalities of all living things

To illustrate the fact that the entire living world, not just the human part of it, is covered by the umbrella of Darwinian medicine, I thought I’d briefly highlight three things that we humans have in common, health and fitness wise, with other organisms on this planet.

1. All organisms express a suboptimal phenotype when they are exposed to environmental conditions that match poorly with their biology
Among evolutionary health enthusiasts, it’s well known that we humans express a suboptimal phenotype when we are exposed to environmental conditions that differ markedly from the conditions that are characteristic of the environments in which most of our evolution took place. This is also true for other organisms. If you take a panda, a bear, or any other animal out of its “natural habitat” and put it into a very different one, its bound to be hit by the effects of evolutionary mismatches. The force of this hit will largely depend on how different the new environment is from the old one. Even microbes, which are arguably very different from humans, are vulnerable to mismatches in both space and time, although they are capable of evolving a lot more rapidly than multicellular organisms.

2. All organisms have evolved various instincts, immune defenses, and/or weapons that help them ward off dangers and survive
Many, if not all, of the processes related to health and disease that take place inside the human body are somehow related to immune system functions. This can partly be understood on the basis that there has, over evolutionary time, been strong selection for powerful human immune functions, because microbial pathogens and parasites were among the greatest threats to our ancestors’ survival. We humans are not unique in this respect. All organisms that exist on this planet today have evolved various instincts, immune defenses, and/or “weapons” that help them effectively compete with other organisms and ward off dangers. If they hadn’t, they wouldn’t have been in existence. These basic facts regarding the workings of life have far-ranging implications for health, nutrition, and medicine. For example, the realization that plants produce powerful compounds that many animals are not very good at detoxifying can help guide nutritional science, irrespective of which species that’s the focus of the research, and the fact that microbes such as Bifidobacterium animalis produces bacteriocins that inhibit the growth of some other microbes can help guide the development of effective probiotics for different animals.

3. All organisms are shaped by their developmental experiences
The environmental stimuli a human child is exposed to when it’s in the womb shapes its development and affects its susceptibility to various diseases later in life. Some of this effect probably arises as a result of adaptive processes shaped by natural selection, in which the child is using early exposures as cues to predict its future environment. The developmental trajectory of other organisms is also affected by early life exposures. By investigating these processes and tracing their evolutionary paths, we can potentially shed light on many medical observations and questions.

The bottom line

It’s a mistake to think that we humans are detached from the other organisms that make up the ecosystem of the Earth. We differ from other organisms with respects to our physical appearance and biological make-up and needs; however, we’re not alone in this respect: bears obviously differ from pandas, sheep differ from cows, and so on. What’s sometimes forgotten is that these differences all came to be as a result of evolutionary processes that are governed by a common set of Darwinian principles.

The evolutionary reasons as to why we humans are vulnerable to disease are similar to the evolutionary reasons as to why other organisms are vulnerable to disease. Darwinian medicine isn’t just useful in the context of human health care and disease prevention; its principles are also applicable to the medical care of other organisms.

Pictures: 1: Creative commons picture by Ian Dolphin. Some rights reserved. 2: By Ray Hennessy on Unsplash.

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