By Joan Ebsworth, guest writer for sense*, biologist and mother of sense* Founder, Jonathan on the biology and ethics of vegetarianism. Are humans designed to eat meat?  Do we have the right to slaughter animals in the way we do? 

Biology was the place to start

The following comments are my personal feelings around the topic of eating dead animals and becoming a vegetarian or vegan.  The biology and ethics of vegetarianism is what coloured my original thinking when deciding to give up eating meat.  Read more about becoming a vegetarian or vegan here.

I am a biologist and so the biological reasoning was important for me.  I knew a bit about the structure of the human gut so it was quite easy to work out.

The biology of vegetarianism: teeth, jaw and mouth

I started in my mouth and there was a lot of logical stuff to work on. My dentition (teeth and jaw) did not fit that of a meat eating animal such as a lion (see picture).

My canines would never have been able to kill an animal or tear it apart nor would any human’s teeth.  Just look at the canines that your dog or cat possesses.

My molars are flat and meant for grinding. When I look at the molars in the mouths of my carnivorous dogs and cats there is just no resemblance. Their sharp carnassials (back teeth)  are so different and often overlap so they become self-sharpening. They are lethal.  Like razors.

Enzymes in the mouth

The enzymes in my mouth relate to carbohydrate digestion and not protein, making me think that our human ancestors were much more likely to be eating tubers and fruits, nuts and seeds rather than meat.

Stomach acid

Then there is stomach acid.  We make hydrochloric acid in our stomachs for a number of reasons but the concentration of acid in the stomach of a carnivore is much stronger that in a human.

In fact research shows that vegans have far fewer problems with stomach issues than do meat eating omnivores.

Most of these stomach issues end up with the person being prescribed an anti-acid pharmaceuticals when in reality they should be prescribed betaine hydrochloride to increase their acid levels to help them digest their meat.

Guts and intestines

Eventually we reach the intestines.  Now humans have a long gut –there is no doubt about that.

However carnivores like big cats, have extremely short guts.

If meat stays in the gut for a long time, as it does in humans, then it will putrefy.

The putrefaction products are quite nasty chemicals and it is thought that they could be cancer inducing.

Again, there is research to indicate that vegans suffer less colon cancer and other gut problems.

It can take almost 2 days for plant foods to pass through the human gut.  Meat can pass through a carnivore’s gut in hours as they really do not want that putrefaction to take place.

Those were my biological reasons for changing my diet 50 years ago.  There seemed to be certain logic in it for me.

Vegetarianism: the ethics

Ethically?  Well –I could never ever kill an animal if my life depended on it.  I loathed dissecting animals at school and university.

If they were presented dead then I could cope but often we were expected to kill them ourselves and I could never do it.

Sentient beings

Animals are sentient beings.  The fear and pain that they must endure when they are slaughtered –I just cannot even contemplate.

The living conditions that so many have to endure is also something that just isn’t right.  Chickens kept in tiny cages –just egg laying machines. Horrible.

Cows having their calves taken away from them so that humans can drink their milk and consume other so called “dairy products”.

Have you ever listened to a cow that has had her baby taken away? It is heart breaking. They have just given birth and the baby has been removed. Just think what a human mother would feel if that happened to her.

As I say –these are sentient beings with real feelings.

Milk is not meant for adults

The thing that bugs me is that milk was only ever meant for baby mammals and never for adults.  We lose the enzyme for milk digestion very early in our lives and this is why so many humans are intolerant of milk products.

If we all stopped drinking milk or eating dairy products from an early age then a huge amount of dairy production would stop, helping our environment.  For more on the environmental impact of eating meat, see here.

Yet some humans go on guzzling milk products all of their lives.


A few years back I read Ozzy Osbourne’s autobiography (book club choice – not mine).  He worked in a slaughterhouse aged 16 years old. His descriptions of that work were horrific.

Don’t ever think that the dead animals that you eat from your plate, died humanely or peacefully because they didn’t.  Most people never think about these things.

Maybe they should.

I rest my case for being a vegetarian / vegan.

This is not a sense* article.  The views expressed in this article are those of the author so there may be opinions or statements in this article that are not approved by sense* and do not represent the views and opinions of the company.