Every aspect of the organismal design, including organismal nutritional requirements, which may be defined as the nutritional input that’s required to produce physiological competence, is a function of evolution via natural selection. This Darwinian view of nutrition is undoubtedly unfamiliar to a lot of people, as mainstream nutrition may be said to be of a non-evolutionary nature; however, from an evolutionary point of view, it seems self-evident that there’s a Darwinian basis to nutrition. After all, it makes absolutely no sense for that aspect of life to be exempt from the natural laws that govern every other aspect of it.
Darwinian nutrition depicted
Not so long ago, I described my Darwinian view of diet and health in an article here on the site. So as to clarify the concept, I’ve now created an infographic that depicts the nutritional evolution of a hypothetical population. The population in question is composed of humans; however, it could just as well have been made up of panda bears, lions, or butterflies, for the simple reason that all living things on this planet evolve via the same fundamental (Darwinian) mechanisms.
Some important things to keep in mind
Various health and lifestyle-related factors have to be taken into account when the nutritional requirements of a population or individual are ultimately to be determined
It’s important to recognize that any major change in the exposures or activity pattern of a population may have nutritional implications. For example, if a group of humans suddenly start spending more time indoors, and hence, are exposed to less sunlight than before, they may naturally need to take in more vitamin D via their diet in order to maintain good health. Furthermore, individuals may differ somewhat with respect to their nutritional needs even if they belong to the same group. This inter-individual difference exists not only because of genetic variation (Note that certain genetic disorders are associated with altered nutritional needs), but also because of variation pertaining to physical activity pattern/level, disease load, stress levels, etc. If for example a tiger were to be infected by a parasite and develop a chronic illness of some sort, it would be expected to crave and require a different mix of foods/nutrients, for the simple reason that such an insult will have physiological, immune-related effects.
Epigentic functionality allows for adaptation on much shorter timescales than what selection on allele frequencies permits
If for example a human is exposed to energy-deficient conditions early in life, such as in utero, its phenotypic development will be adjusted accordingly as a result of plasticity in gene expression. Most likely, the person in question won’t grow to be as big and tall as if he/she were exposed to energy and nutrient-rich conditions early in life. This adjustment may simply be perceived as an acute response or adaptation to nutritional meagerness; however, it may also be understood as adaptive accommodation to expected future conditions of life. Irrespective of the view that one gravitates towards, it’s important to recognize that there’s a ceiling as to the level of customization that can be achieved this way. Additionally, it’s important to acknowledge that this epigenetic feature is ultimately a product of ‘conventional’ Darwinian selection. In other words, it’s by no means “something different” that falls outside the bounds of Darwinism.
Co-living allows for ‘nutritional networking’
No organism lives in complete isolation. This is relevant to discussions about nutrition, as organisms affect each other’s health and fitness by shaping the nutritional conditions they live under. For example, a person’s gut microbiota acts on and evolves in response to the foods that that person eats. If the individual in question suddenly starts eating considerably more of a certain type of plant, those microbes that are best able to utilize the substrates that are present in that plant will come to find themselves in an advantageous position. This again will affect other organisms in the vicinity, including the human host, in part because various products (e.g., short-chain fatty acids) will result from the bugs’ actions. The person in question may also come to acquire new bacteria, such as via contact with other humans or through his diet, something that may have consequences for the digestion and utilization of certain foods within the system. What’s important to recognize though, is that while seemingly intertwined with the person in question, such organisms are not a part of him. Rather, they are a part of his environment; and hence, represent a selective pressure.
Pictures: 1: Created using pictures from freepik.com. 2: Photo by Victor Freitas on Unsplash. 3: Creative commons picture by Christoph Bock. Some rights reserved. 4: Creative commons picture. Some rights reserved.