Suppose my skin were impregnated with chlorophyll and I could practice photosynthesis. It’s what plants do to turn sunshine into energy. If I spent a full day laying naked in the sun, I would produce the energy equivalent of one cocktail peanut.
This illustrates two main differences between plants and animals.
The average woman (me) needs to ingest the caloric equivalent of 333 cocktail peanuts per day. Animals burn a lot of energy, but then again, we do a lot in a day. Plants lead slower lives.
But compared to a plant, we’re fairly small, measured in surface area. The average human has about one square meter of skin. Plant leaves are designed to maximize surface area. A mature, healthy tree has about 200,000 leaves and a photosynthesizing surface area of around 500 square meters. On a sunny day, a mature tree produces enough energy to fuel a big, active man — a soldier, for example.
But instead of waging war on us, they make our food. Animals eat plants. That makes us the top of the food chain, right?
I’m not so sure. Consider the apple. The apple tree makes apples to seduce us into taking the fruit, eating it (the energy equivalent of a mere seven cocktail peanuts), and depositing the core elsewhere, which may be a good place for the seeds to grow. Apple trees have convinced us not merely to distribute their seeds but to care for them. We’ve allowed the trees to take over 200,000 acres of Washington State in exchange for giving us 10 billion apples per year, and we think it’s a bargain.
Wheat controls America’s Great Plains. Corn runs rampant in Iowa. Olive trees have conquered southern Spain. Rice rules Japan. The lack of potatoes almost destroyed Ireland, proving that we need them more than they need us.
We’re not the only animal that does plants’ biddings. Grass wants to be eaten (or mowed). It grows from beneath the soil with only the leaves above. Grazing animals, like buffalo in the prairies, eat the leaves, which grass can easily replace. But the animals also eat weeds in their entirety, which kills them. This is why a healthy, regularly mowed lawn remains weed-free. (We are weekend substitute buffalo.) Grass has found the perfect ecosystem in suburban environments. In some places, grass is even mandated by law.
So much for being in charge. They’ve co-opted our municipal ordinances. In any case, we’re hopelessly outgunned.
On Earth, measured by mass, there is 100 times more plant life than animal life. We worry about the consequences of global warming, and it would be hard on plants, but in the long run, human beings are one species, and there are more than 400,000 species of plants. They are as varied as algae, moss, roses, maples, grapes, and cacti. They will endure, though our orchards and gardens might miss us.
However, scientists are searching for ways to persuade plants to photosynthesize better, since photosynthesis takes carbon dioxide from the air. Plants might save us from ourselves. We speak of our hopes as “green.” Yes, exactly.
That’s why, if I were a plant, I would rule this planet, and you would work for me — for peanuts.
Semiosis 