## Standard human diet

There exist (at least) two alternative, competing philosophical concepts of probability.

One, more naive, is that real-life events are random, and so to model this, we use the probability theory to estimate the likelihood of their occurrence. As an example, when tossing a coin, we do not know whether we will obtain heads or tails. So we assume, for simplicity, that if the coin is symmetrical, then the chance of getting heads is the same as the chance of getting tails, and hence let the probability of observing either be 1/2.

The other, more insightful, is that real-life events are completely deterministic, and driven by the various factors contributing to those events. For example, when tossing a coin, whether we obtain heads or tails, completely depends on how we tossed the coin as well as the conditions of the surrounding environment. In particular, if all these factors were the same, we should observe the same outcome each time. Nevertheless, since there are too many factors for us to control them, it appears as if the outcomes of the tosses were random. So, for simplicity we make analogous modeling assumptions as in the first case.

Whilst from the point of view of practical calculations, it does not matter which philosophical concept we adopt, as far as real-life is concerned, our approach may carry a tremendous amount of weight.

As one example of interest here, many have argued a range of views, often contradictory to one another, on what the *natural* human diet is and hence what the modern human diet *should be*, based on the history of human dietary patterns, going back in time thousands and even millions of years. A common line of reasoning used is that humans are predisposed to a particular way of eating, and won’t thrive unless they follow a particular diet that is being argued as the *natural* one. Such argument clearly contradicts the historical evidence of humans surviving in a multitude of different, sometimes harsh conditions, thanks to adapting their eating habits to the range of foods available in those environments. Indeed, the major flaw of such reasoning, is *failing to see*

- that humans have a choice, which is constrained by the range of available options,
- that the choice they make, results in outcomes, which include genetic changes, that in turn may affect future dietary preferences or digestive abilities, as well as
- that there exist considerable individual differences in human needs and abilities, and that it is important for an individual to respond to those needs, in order to achieve best overall health and happiness outcomes.

So, although it would be convenient to assume that the world has made a choice for us, this may be a too naive, and too simplied model of the reality. The world may not be random, but it denitely is very complex. Classifying diets may help, to some extent, in understanding of how it works, but cannot replace the reality or remove our freedom to choose what we desire and in doing so, change it. It could be more helpful perhaps, to see the world as the complex result of various actions and decisions, to which we may have some contribution, however small, than as a random outcome to which we have no say.

(extract from “Standard Human Diet: A stochastic modeller’s perspective”, Dr Gosia O’Reilly, draft)