So plants are ignored, but why does this matter? It matters because over-humanising animals and under-humanising plants causes all kinds of problems. A particularly important case in point is in food and farming. I think it likely that many ideas about animal welfare are based on false assumptions that animals want what we want, rather than evidence about what they want. Many popular ideas about the best way to grow crops involve little consideration of plant biology. There is now an obsession with naturalness in food, with a deeply-held assumption that if it's natural it must be good. It is intuitively obvious to people that vegetables that have not been sprayed with artificial chemicals must be more health-giving than those that have. "It stands to reason," people say. But it precisely doesn't stand to reason. As soon as reason is brought to bear, the whole proposition looks extremely shaky. 

Think about it from the plant's point of view. Think like a real, non-couch, potato. A potato is a food store for next year's potato plant. It remains in the soil over winter and the next year, fuels the growth of the plant. This is a very dangerous strategy — to leave a source of food sitting in the soil over winter when animals are hungry. So potatoes are heavily defended, laced with various types of chemicals to ward off all-comers. The world's deadliest toxins are natural chemicals. Just because there are no artificial chemicals on a plant does not mean it is not stuffed full of natural but lethal chemicals. During plant crop domestication, we have bred some of these out, and we deal with many others by cooking and processing our food. Raw potatoes are bad for you for a reason. And this is the general point. Except when handing out bribes, plants don't want to be eaten. Natural plants are tough, indigestible and full of toxic chemicals. The closer a plant is to nature, the more likely it is to be bad for you. This obvious point is almost entirely ignored because no one thinks about plant biology.

At this point, the natural-is-good lobby patiently explains that we have evolved eating plants, so through natural selection, we are adapted to eat them, so they are definitely the very best thing for us to eat, natural selection being the great optimiser. Here again, this argument completely ignores any consideration of the potato's view. Natural selection is also acting on the plant, so for every evolutionary innovation allowing an animal to overcome a plant defence, there is counter-selection for a new defence in the plant. It's a balance, with the plant being eaten more than it would like, and the animal being damaged more than it would like. It is an evolutionary arms race. Ten thousand years ago, we had the brilliant idea of agriculture-enforced unilateral disarmament of plants by people. It's not at all natural, but the result is healthier food. Natural agriculture is an oxymoron.

Agriculture has changed everything for people and for the planet. Now both are in crisis, triggered by over-population, climate change, and water, food and fuel insecurity. Agriculture and plants are central to providing solutions. It's easy to argue that because people have driven ever more intensive agriculture, and this has been a major cause of these problems, the solution must be less intensive agriculture, with less intervention from people — leave it to nature, not science. This is woolly thinking, legitimising an abrogation of responsibility with a call to do less. To tackle these massive challenges, we need active intervention and the kind of ingenuity shown by the first farmers 10,000 years ago. We need to understand plants and, through understanding, learn how to make the most of them.