The Collison Newsletter July 2009


                MEAT – to EAT or not to EAT?*                    

Human Anatomy & Physiology Compared with Carnivores, Herbivores & Omnivores


In November 2007, the World Cancer Research Fund International and the American Institute for Cancer Research published a 537 page report ‘Food, Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective’. The 10 recommendations which are a summary of that report are reproduced in my March 2008 newsletter ‘Prevention of Cancer’.


The report recommends that to prevent cancer in particular, as well arterial diseases like coronary heart disease and stroke, and diabetes, we should “Eat mostly foods of plant origin” and “Limit intake of red meat and avoid processed meat”.


This report, understandably, angered the Australian meat industry (Meat and Livestock Australia), who countered with strong advertising campaigns, commonly attributing, for example, increased brain size and physical vitality to meat consumption. These claims have been strongly argued against (see


There are many eminent researchers and clinicians, such as Dr John McDougall, Dr Joel Fuhrman and Dr Joseph Mercola to name but three, as well as the many societies both in Australia and around the world, that endorse a vegetarian/vegan lifestyle as the only way to full health and disease prevention. My book ‘How to Live to 100+ Years free from Symptoms and Disease’ sets out the Dietary Guidelines for health and disease prevention. These are in accord with the recommendations in the above report and the researchers and health societies referred to above.


When it is suggested that meat should be excluded from the diet, or severely restricted in the diet, the questions frequently asked are along the following lines:  “We have always eaten meat …. our bodies are made for us to eat meat…. what is wrong with eating meat?”


The simple answer is that meat (animal products) is not healthy for us. The Doctors mentioned above have published extensively in articles, books and newsletters on their websites setting out the supportive evidence for their beliefs and recommendations. Likewise the vegetarian/vegan societies have various publications which set out their views and beliefs, and these can be accessed.


In this newsletter, to add support for a diet that excludes meats and other animal product, the comparative anatomy and physiology of humans, carnivores, herbivores and omnivores will be briefly looked at.


·       Carnivore

A carnivore is an animal that eats mostly meat. They are carnivorous. The word Carnivora comes from Latin, where Carne means ‘flesh’ or ‘meat’ and Vorare means ‘to eat’, hence ‘meat-eater’. Scavengers are carnivores that eat other animals that they did not kill themselves and which have been dead for some time.


·       Herbivore

A herbivore is an animal that only eats plants. They are herbivorous. Again, the word comes from Latin. Animals that are herbivorous cannot chew or digest meat. Some will eat eggs and occasionally other animal protein.  A ‘frugivore’ is a herbivorous animal that eats mainly fruit. A ‘folivore’ is a herbivorous animal that eats mostly leaves. Animals that eat mostly grass are ‘grazing’ animals.


In some ways it is easier to be an herbivorous animal than a carnivorous one. Carnivorous animals have to find and catch the animals that they eat, and sometimes the animals that they want to eat fight them. Herbivorous animals have to find plants that they want to eat, but they do not have to catch them and of course they do not fight! Partly for this reason, most animals are herbivorous. There are many more herbivorous animals in the world than carnivorous.


·       Omnivore

An omnivore is an animal that eats both plants and animals as its primary food source. They are omnivorous. Omnivore comes from Latin, where Omne means ‘all’ and Vorare means ‘to devour’ or ‘to eat’. They are opportunistic, general feeders not specifically adapted to eat and digest either meat or plant material exclusively. Although there are reported cases of herbivores eating meat, as well as examples of carnivores eating plants, the classification of omnivore refers to the adaptations and main food source of the species in general, so these exceptions do not make either individual animals, or the species as a whole, omnivores.

Anatomy and Physiology 

Most humans today eat a wide variety of plant and animal foods. Thus most humans can be called ‘omnivores’. However anatomically and physiologically, we are essentially herbivorous.


Biologists have established that animals which share physical characteristics also share a common diet. Let us therefore compare humans to herbivores, carnivores and omnivores from a physical point of view.


The following is modified from the work of Dr Milton Mills published as ‘The Comparative Anatomy of Eating’.  He compares the typical anatomical features of carnivores, omnivores, herbivores and humans.


·       Facial Muscles

The facial muscles in the herbivore and human are well developed, and are made up of masseter and pterygoid muscles.  In the carnivore and omnivore they are poorly developed with only temporalis muscles, to allow ‘wide mouth gape’.


·       The Jaw

The jaw motion, in the herbivore and human, has good side-to-side and front-to-back movement. In contrast, the carnivore and omnivore have minimal side-to-side movement.


The restricted movement of the jaws of carnivores requires them to tear chunks of flesh from their prey and swallow it whole. The full movement of the jaws of herbivores and humans allows them to grind up fruit and vegetables with their back teeth.


·       Teeth

The incisor teeth of the carnivore and omnivore are short and pointed, whereas the herbivore and human incisors are broad, flattened and spoon-shaped.


The canine teeth in the carnivore and omnivore are long, sharp and curved, capable of tearing flesh. The ‘canine’ teeth of herbivores and humans are pathetically small, and canine in name only.


The molar teeth in humans are like other herbivores, flattened with nodular cusps, and allow grinding of fibrous plant foods. Carnivores lack these flat molars which are instead sharp and jagged. Omnivores may have some flattened molars.


·       Chewing

The carnivore does not chew, but swallows the food whole, as does the omnivore which may also do simple crushing. In both herbivores and humans, extensive chewing is necessary.


·       Saliva

There are no digestive enzymes in the saliva of carnivores and omnivores. The saliva of both herbivores and humans contain carbohydrate-digesting enzymes (amlyase).


·       The Stomach

Herbivorous animals have either a simple stomach, or one with multiple chambers. Humans have a simple stomach, as do carnivores and omnivores.


The stomach acidity (pH) is very low in carnivores and omnivores, being less than or equal to pH 1 (with food in the stomach). In contrast, although the stomachs of both herbivores and human are acid, they are much less so, with the pH being in the region of 4-5 (also with food in the stomach).


The stomach capacity in herbivores and humans is much less than carnivores and omnivores, namely 30% compared to 60-70% of the total volume of the digestive tract.


The carnivore swallows its food whole and relies on the extremely acidic stomach juices to do most of the digestive work. The high acid content in the stomach of carnivores also kills the potentially dangerous bacteria that would otherwise sicken or kill the meat-eater.


Humans can cook meat to kill some of the bacteria and make it easier to chew, but it is clear that humans, unlike carnivores, are not designed to easily digest meat.


·       Length of the small intestine and colon

Carnivores and omnivores have short intestinal tracts and colons that allow meat to pass through relatively quickly, before it has a chance to rot and cause illness. The length of the small intestine in carnivores is 3-6 times the body length, and 4-6 times in omnivores. In herbivores, it is 10 to more than 12 times the body length, and in humans it is 10-11 times.


The colon is long and sacculated in both herbivores and humans, but short and smooth in carnivores and omnivores.


The long human intestinal tract actually makes it dangerous for people to eat meat. The bacteria in meat have extra time to multiply during the long trip through the digestive system, and meat actually begins to rot while it makes its way through the intestines. Many studies have shown the link between meat eating and colon cancer in humans.


·       Nails

Those animals that eat a plant-based diet have shorter and softer nails (flattened) or hooves in contrast to the sharp claws of the meat eaters, necessary to tear flesh.


Comparing the anatomies and physiology of humans, herbivores, carnivores and omnivores clearly illustrates that the human body is designed to run on a plant-based vegetarian/vegan diet. Humans have absolutely none of the distinguishing characteristics that either carnivores or natural omnivores have.


Although most humans are ‘omnivores’ in so far as they eat meat and plant foods, the anatomical and physiologic make-up of the human body points clearly towards a dominantly plant-based diet as the ideal for health. There is some good evidence that humans should, in fact, be frugivores (fruit-eaters) or at least have a dominance of fruit in their diet.


*Copyright 2009: The Huntly Centre.

Disclaimer: All material in the website is provided for informational or educational purposes only. Consult a health professional regarding the applicability of any opinions or recommendations expressed herein, with respect to your symptoms or medical condition.



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