Biodiversity starts in the stomach

What is Biodiversity?

By Ole Sandberg.

The Convention on Biological Diversity (CBD) defines biodiversity as:“the variability among living organisms from all sources including the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.

And it defines an ecosystem as: “a dynamic complex of plant, animal and micro-organism communities and their non-living environment interacting as a functional unit.

The Ecosystem Approach, which is the primary framework for actions under the Convention, specifies that:This definition does not specify any particular spatial unit or scale. Thus, the term “ecosystem” can refer to any functioning unit at any scale. Indeed, the scale of analysis and action should be determined by the problem being addressed. It could, for example, be a grain of soil, a pond, a forest, a biome or the entire biosphere.”

To that I would add that it can also be your body. Or even a part of your body, such as your stomach and intestines. This part of the definition  – that there is no particular scale and that you can zoom in our out – will  be relevant for this talk.

Our bodies are also ecosystems

A human body has around 30 trillion cells. Of those somewhere around half are cells of other organisms: bacteria, fungi and other microorganisms. They live in our skin, our mouth and nose, and everywhere else in our body, but most of them live in our guts. DNA analysis has shown that there are at least 800 different microbial species in a human body and thousands of different subspecies. That is a lot of biodiversity in very little space: just one human body is an ecosystem that is home to trillions of organisms from hundreds of different kinds. A healthy body, that is.

Most of these microorganisms are bacteria. Until quite recently it was believed that bacteria and other microorganisms were mostly bad and that anything that is “foreign” to an organism is harmful to it if it gets “infected”. But the fact is that we cannot function without these “foreign” creatures. A human body is not a functioning body without them. They digest our food by breaking down carbohydrates and they produce vitamins and other nutrients our body needs. They regulate our blood and the proteins needed for our bones. They are also essential to our immune system as they – the good bacteria – fight off the competition from the bad ones.

So, our bodies would not function without them. One could say, that they are not just organisms living within us, but that they are us. We would not be us without them. Together, we are one organism.

Biodiversity and human health

But they are not just essential for our bodily function and well-being. The biodiversity within us also regulates our mental health, our mood, and our thinking. Studies have shown that the human brain is connected directly to the stomach and is affected by the life that exists within it. Without the right balance of biodiversity in our internal ecosystem, we are more likely to suffer from depression, anxiety, lack of concentration, and cognitive diseases like Alzheimer’s and dementia. So our very personality – our thoughts – is shaped by the biodiversity within us.

An advertisement said “You are not you when you’re hungry.” That might be an exaggeration, but it is true that you are not you without the bacteria in your gut, and if you let them go hungry you will suffer too, and it will affect your mind.

I personally noticed that years ago when I moved to the United States. After a while I noticed that I wasn’t feeling right – physically and mentally. I found that one problem was the food. American food is different from what I grew up with. Especially the bread has almost no nutrition. I grew up in Denmark and was used to eating whole-grain bread with lots of seeds and other things that are difficult to digest. Instead of going straight through you, it stays in the guts for a while where it takes some time for it to break down. That means that it gives nutrients to all the microbes in your guts all the way through. The microorganisms in my gut were used to getting this nutrition. Now I wasn’t feeding them. And when they don’t feel good, neither do I. So I started to bake my own bread.

What this also shows is that health is cultural. Maybe an American who grows up with their fluffy sandwich bread won’t need Danish rugbrød. Actually, it might give them indigestion because they lack the microbes who have been trained especially to digest that. They need other things. Things their stomachs are used to. There are studies that say people from cultures where rice is part of the daily meal are better at getting nutrients from rice – they have gut flora that are experts in dealing with that. I think this is interesting: that the culture we are raised in does not just shape our thoughts and habits but is literally in our bodies. When we eat, we digest our culture, and it becomes part of us.

Microbiome diversity loss

So, where do all these microorganisms that are essential to our bodies come from? Some of them we receive on the day we are born as we pass through the birth canal. Others come from our mother’s milk. But many of them we eat: they come on the soil and the dirt on the plants we digest.

We also get them as children when we play outside on the ground and in nature. That’s another cultural difference: in some places, children are kept mostly inside and in others they play outside all the time. This exposes them to different microbiota in their environment. Microbiota that might be especially suited for their bodies to live in those environments.

So we are all different ecosystems with a diversity of different microbiomes that are adapted to and shaped by our cultural and natural environment. Except. This diversity is also disappearing. Africa is the continent with the highest genetic diversity among humans. Not so strange, since humankind started in Africa. It also has a high degree of microbial diversity in those humans. But globalization and urbanization is reducing that.

When people who lived in rural areas and lived on a diet of local foods – typically roots and vegetables that are high in fibre – move to the city and start eating the same processed foods that are found everywhere in the world, they also start to lose those microbes they used to have. This leads to health problems. But it is also a form of biodiversity loss. A study I found, said that “ancient microorganisms, such as fiber-degrading bacteria, are at risk of being eliminated by the fast paced globalization of foods and by the advent of westernized lifestyle.” If that happens, we might lose our ability to digest certain foods.

The environment is part of us

Anyway. The point is, that we are not just our human cells and our human DNA. A human organism – indeed any organism – is also made of the many other organisms that live inside it and are part of it. But these organisms come from the outside. They come from the broader environment and are shaped by the food we eat which is shaped by the local conditions and culture.

So it is not really possible to make a clear distinction between inside and outside, between environment and organism, or between “self” and “other”.

The biodiversity that is inside us – and which is us – comes from the outside and becomes the inside. Without biodiversity in our environment there won’t be biodiversity in our guts. And that means there won’t be any us. Humans and all life depend on biodiversity.

If I don’t feed the microbes in my gut with the nutrients they need, then I won’t feel well. But to feed those microbes I need to take care of my environment, my community, and – in the larger picture – the planet and the atmosphere. Because that is the source of my well-being. It is the source of me.

I especially need to take care of the soil that is home to so many microorganisms. Microorganisms that are essential, not just to my body, but to the Earth. Because if the soil and the Earth is not doing well, then I won’t feel well either.

Soil is the source of life

The soil on this planet is the home for the largest amount of biodiversity. And we become part of that biodiversity when we eat food that is grown in that soil. The biodiversity in the soil is also essential to maintain that soil. But the ways we grow food can either destroy the soil and the microbes in it, or it can help sustain it. Intensive agriculture is one of the leading drivers behind biodiversity loss today, because it destroys the living soil which is necessary for us to grow food at all. But Agriculture can also be regenerative and help heal the soil.

This is why food is so important. It is not just something we eat to get full so we can go on with our day. It made me so sad when I moved to Iceland and saw how popular food replacement products like protein drinks are, even among people who are not exercising. Food should be about enjoyment. About life. When we eat food, we are eating and creating culture. And we are connecting to the land we live in and the planet we live on.

If my body is an ecosystem that hosts trillions of smaller organisms, we can also zoom out and think of me as an organism in a much larger ecosystem. Ecosystems are nested within each other and are not defined by any particular scale. An organism can be an ecosystem for other organisms and an ecosystem can function like an organism.

In that sense, maybe the whole planet Earth could be considered both an ecosystem and an organism – just like body. In that sense, we are all like the microbes in my body, except we are part of the superorganism called the Biosphere. We are parts of a larger whole and our well-being depends on the healthy function of that larger whole – just like its well-being depends on us.

The author is a philosopher working at the Icelandic Museum of Natural History and at the University of Iceland and a member of BIODICE.