Skip to 0 minutes and 1 secondHi, my name's Dr. Dan Bebber, the Department of Biosciences. Gone are the days when we foraged, hunted and bartered for our food. Today, almost everyone on Earth pays a retailer for food. What determines the food choices we make, how much we pay, and the consequences for ourselves, our society and environment? We are going to look at those factors that make up the food system. If you grow all your own food using saved seeds, rain water and garden compost, then cook it on a wood fire using your own wood, then your food system is relatively simple. For most of us however, the food system is far more complex. Let's take a grain of maize to illustrate the complexity.

Skip to 0 minutes and 48 secondsMaize was domesticated nearly 7,000 years ago in ancient Mexico. Now it's the world's most important crop in terms of total production. Starting with the maize grain, how does the farmers select which of the hundreds of varieties to plant? Will the grain be used to feed people, cattle, or even for biofuel production? Might the farmer choose a heritage variety like this one? Or a genetically modified variety that resists herbicides? This would allow weeds to be controlled without killing your crop. The farmer's choice will also be affected by climate, the prevalence of pests and diseases, and financial considerations. So the food system is already complex and we haven't even prepared the field yet.

Skip to 1 minute and 35 secondsOften, soils are tilled or ploughed to help control weeds. But fields can be left untilled to improve soil structure and reduce erosion. No till and minimum till farming are widely used in the USA. However, that means more weeds and more weed killer to control them. Once the grain is drilled, the farmer must apply fertilisers, water and pesticides at the right times. These can be costly, and have environmental consequences, like water pollution, impacts on pollinators and other beneficial organisms, or greenhouse gas emissions. Aside from the price of grains and agro chemicals, how does economics affect the farmers decision? Does the farmer receive government subsidies to grow maize? Or to set aside land for biodiversity conservation?

Skip to 2 minutes and 26 secondsWill the price of maize on the international market rise or fall? Maize is a commodity crop, meaning it is bought and sold on international markets by commodity traders, just like oil gas and gold. The price of European maize is affected by production levels in the USA. If production goes up, the price goes down. Crop price can have environmental impacts. Destruction of tropical forests for agriculture increases when prices are high, because farmers have an incentive to grow more. The USA is the world's largest maize producer, so the strength of the US dollar will affect prices.

Skip to 3 minutes and 6 secondsOne of the most surprising things about maize is how little is eaten directly by humans 40% of US maize is converted to ethanol for biofuel, while a similar amount is used to feed cattle, pigs and chickens. Of that remaining, most is converted to maize starch or corn syrup, which are found in almost all processed foods. The syrup in particular is linked to weight gain and diseases, like diabetes.

Skip to 3 minutes and 34 secondsCommodity trading companies operate huge logistics networks, transporting and shipping grains around the world. These companies then sell the grain to processors, who sell the processed products to food manufacturers, who then sell the foods to retailers, who then sell it to you, the consumer. What then? That's not the end of the story. Consumers pay a huge role in determining the price of food, and so how much of a crop gets planted. If people ate less meat or used less fuel, than demand for maize would drop. Around a quarter of the food purchased for consumption gets thrown away. Again, decreasing food waste would reduce demand. Food waste contributes to climate change, because decaying food releases CO2 to the atmosphere.

Skip to 4 minutes and 24 secondsThe example of a simple grain of maize shows us that decisions made by consumers have implications for environmental protection, biodiversity, climate change, health, animal welfare and economics. When choices are made by billions of people, the effects can be huge. This is why we need to understand the whole food system, and how changing one part can affect the whole planet.

A journey round a food system

In this video, Dr Dan Bebber describes the complex system of food production using maize as an example. This includes the decisions farmers must make while growing the crop and how the demand and price of maize depends on global production levels, international markets and on the consumers themselves.

Having watched this video we are now going to consider food cultures around the world and whether they’ve become more homogeneous.

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This video is from the free online course:

Future Food: Sustainable Food Systems for the 21st Century

University of Exeter