When Suffolk headteacher Kath Cook began a primary school project to educate children about the origins of food, she never thought it would result in death threats.

But shortly after Peasenhall Primary School started up a scheme to raise and slaughter pigs - with the backing of parents - the school was besieged by threats from animal activists.

The pigs are not school pets. They do not have names and the children will not witness them being slaughtered. The strong opposition, however, comes from groups who appear to object to the slaughter of any animal for food.

This is not an isolated case. In 2010, Andrea Charman stepped down from her job as headteacher of Lydd Primary School in Romney Marsh over a similar project involving sheep, although she was later reinstated after overwhelming public support.

Animals - whether we choose to pamper them as human companions or consider them part of our diet - are clearly a highly emotive subject.

Perhaps we should look more closely at the biological reasons for and against eating meat. It is perfectly possible to live a healthy life as a vegetarian or vegan. Some micronutrients, such as iron and zinc, are difficult to obtain from vegetables alone, but dietary supplements can overcome these deficiencies.

As a species we are omnivores, with the mechanical and chemical biological systems to eat and digest meat and derive essential nutrients from it. That some people choose not to is a personal rather than a biological choice. But why do we choose to eat beef and not, say, cats or dogs? Why did so many people react with disgust and loathing to the news that some processed foods contained not beef, but horsemeat?

The recent horsemeat scandal highlighted the complexities of our food chains nationally and internationally. But were there any genuine health dangers? Horsemeat is regularly eaten in France and many other countries. The controversy in the UK was about more than mislabelling and the potential dangers posed by drugs that are not supposed to be in the human food chain. Nor was it only a case of being angry at the less-than-strict tracking and labelling of our meat. It was, rather, a very British response to eating horses, an animal regarded in this country almost as affectionately as domestic pets.

But why such disgust? There are valuable discussions to be had on this issue in the classroom. Why, for example, do we eat cows, “cuddly” lambs, intelligent pigs and even “cute” rabbits? (Ask anyone who has had a pet rabbit if they would consider eating it - even if it had died a natural death - and you would provoke the same appalled reaction.)

So what guides our choice of which animals we eat? If we go back in human history we know that 10,000 years ago our Palaeolithic ancestors ate dogs. Analysis of preserved human faeces found in a cave in southwest Texas showed the residue of stewed dog brains.

Even today, some cultures, such as those of South Korea and China, have no problem with consuming dog, while others are revolted. In Britain, it is because the dog is seen as man’s best friend, but other cultures are repelled because their religion considers the animal to be vermin and unclean.

I have eaten alligator in Florida (chewy and a little fishy), rabbit (not a pet), shark, horse, snail and a host of other creatures. I would, however, draw the line at a dog or a cat. The ghastly eating tasks on I’m a Celebrity . Get Me Out of Here, filmed in Australia, where contestants must munch spiders, ants and obscure native creatures such as witchetty grubs, show us that many things can be eaten safely. It is our own psychology that is the greatest deterrent.

We do not eat our pets, for example, because we have a strong emotional attachment to them. Indeed, the joke in Britain has often been that the elite prefer the family Labrador to their children. We tend to anthropomorphise our companion animals, and eating a loved one when they have for years provided unconditional affection through a nudge, nuzzle, lick or purr is tantamount in our minds to cannibalism.

This brings us to one of the most important areas of psychology - attachment theory, which is also the key to understanding how human relationships evolve. The bonds we develop with our parents and other key figures in childhood affect the way we develop emotionally. As adults we often seek to recreate them in our personal relationships. To a lesser extent, however, we develop important attachments to, and learn valuable lessons from, our pets.

The demise of a much-loved animal can leave us as distraught as the death of a close relative. It is also an ideal way to broach the subject of bereavement to little children, as the loss of a pet is often their first encounter with death. There is much we can learn from animals, and much we can teach children about the need to care for them and show them respect. No wonder, then, that the thought of eating them invokes disgust.

But it is also important that young people learn where our meat comes from and how farmed animals should be treated. What we buy in the supermarket looks so far removed from the animal it comes from that the emotional link between a cute-looking lamb and the leg we have for Sunday lunch is severed. Children need to learn that although we may eat them, these animals also need respect in the way they are farmed and ultimately dispatched.

The horsemeat scandal has made us aware that cheap meals will not always satisfy our psychological needs. Most of us want to know what we are eating and where it comes from. Now there are moves by major suppliers to use more locally produced meat, which is good news for local farmers and butchers although it may mean an increase in price. Only the consumer will decide if it is worth it.

But I would argue that we should pay more attention to, and have greater knowledge and understanding of, the process of our food production.

Perhaps projects such as that at Peasenhall School could even serve the aims of the animal activists: fewer children might want to eat the sausage, pork or ham put on their plate after caring for pigs at school. At the very least it should promote a greater degree of respect for the animals we rear for food. And surely that can only be a good thing.

James Williams is a lecturer in science education at the University of Sussex, School of Education and Social Work. Follow him on Twitter @edujdw

What else?

Key stage 1: Food mobile

Make a mobile showing the five food groups from the Eatwell plate with this easy-to-use template from Louath.

bit.lyFoodGroupMobile

Key stage 2: What’s in food

Have you ever wondered what is in the food you eat? Find out with this video from Teachers TV.

bit.lyWhatIsInOurFood

Key stage 3: The great debate

Is it right to eat animals? Explore this question with a lesson from Klingsor covering factory farming, and Hindu and Jewish beliefs.

bit.lyEatingOurPets

Key stage 4: Green approach

Take a look at this interactive tutorial from Meat and Education on the subject of eating meat in a green world.

bit.lyEatingMeat

Key stage 5: Food miles

Explore the pros and cons of meat eating and food miles with a card activity on environmental, farming and health issues from TES partner Wellcome Trust.

bit.lyMeatvsFoodMiles.