Our genes and our diet

Chimpanzee Mouth

Vegetarian, omnivore, carnivore, pescatarian – which is the correct diet and what does logic, our genes and our anatomy tell us?

Suppose you came across an object you’d never seen before, and you wanted to work out its purpose? What would you do? I think most people would look at its general construction and ask questions such as:

  • How is this object constructed and of what materials?
  • What are its major parts?
  • What are its most likely functions?
  • Where in the world did it originate? If its location is/has been changed, does it need or has it needed some special adaptations to adapt to its new location?

If we applied these questions to ourselves, we might more readily understand how to differentiate between the accurate and vastly inaccurate so-called ‘health information’ that is readily available today. Clearly this is an enormous topic so to start I just want to focus on the most basic elements of diet and on the role of the head. I will address many specific sub-topics in the coming weeks.

Today’s question: What can we learn about our diet from our heads?

The construct of the HEAD

ONE HEAD has the five major organs brain, ears, eyes, nose, and mouth. The most notable moving parts are the eyes, which allow us to see food and the jaw which allows us to bite and chew food.

Each organ of our entire body, and the head is no exception, is composed of nerve, blood, bone, and skin cells (of which some are external and some internal). There are also specialized structures in the mouth called teeth, which are composed of enamel and unlike bone, do not contain living (potentially replacement) cells as bone does. The mouth also contains another specialized muscular organ, the tongue, that is vital for taste, chewing and swallowing as well as creating sounds, especially speech.

From an evolutionary perspective, almost every part of the head has played an essential role in nutrition. The eyes, ears and nose have allowed us to detect the presence of potential food and after we hunted or gathered our tasty morsels, our tongue and teeth then allowed us to eat it. However, since relatively few of us have been involved in food gathering and/or production for some generations, our teeth may be our foremost guide to the foods that best suit us today.

Our incisors (eight – four in the upper and four in the lower jaw) are in the middle of the front of our mouths and each has a flat edge that is adapted for shearing and cutting food. Being in such a prominent position, this may be the most important function.

Our canines or cuspids (four – one on the jaw side of each pair of incisors) have a sharp edge and are for tearing food.

Our pre-molars (eight – two pairs in the upper and lower jaw on each side) have flat surfaces with ridges for crushing and grinding food into smaller pieces to make it easier to swallow.

Our molars (twelve – three pairs, upper and lower on each side of the jaw) have a large surface that helps them to grind food.

What our HEADS would lead us to conclude about our diet?

It’s not necessarily logical to conclude that because we have such a high proportion of our teeth adapted for crushing and grinding food that crushing and grinding should be our primary dental activity. Nevertheless, I think that the very large number of grinding teeth attests to the fact that some types of plant-based diet has been consumed by humans over most if not all their ancestry. Furthermore, the high proportion of this type of tooth strongly supports this ancestry and plants should form a major proportion of our diets.

Nevertheless, the presence of canine teeth, which are in a very prominent position strongly suggest that cutting and tearing teeth are still required by humans and that foods, such as animal flesh that require cutting and tearing should also be part of our healthy diets.

Chimpanzee and Human Diets

Our DNA is only 1.2% dissimilar to the Chimpanzee and it’s logical to think that our dietary adaptations might be similar. Chimpanzee in the wild have a diet that is mostly vegetable/fruit and not surprisingly always those that are in season! They are now known to dig up small crustaceans from mud, to eat insects and to hunt and kill smaller monkeys, whose flesh they eat. So, meat forms only about 3% of their diet in the wild and is eaten on only about 9 days each year.

Taken together these facts suggest that humans have evolved to eat some meat and crustaceans but mostly a diet of fruit and vegetables. However, these facts don’t tell us which dietary proportions are optimal and in the coming blogs we are going to move past the head to try to piece the facts together!

So, till next time ……….

Published by Dr Judy

I am a PhD Geneticist and have spent many decades working in research related to reproduction and cancer. Both are affected by lifestyle, especially ageing and so I am passionate about teaching people how to change their lifestyles to optimise their health.

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