The same species that once believed the world was flat is also responsible for defining the difference between living things and everything else. According to NASA, the current definition groups "life" into four categories: eukaryotes (plants, animals, fungi, protists); prokaryotes (bacteria); archaea (single-celled organisms that share attributes with both protists and bacteria); and viruses. The common traits that cut across all four categories, that all lifeforms share – e.g. the ability to reproduce, to respond to stimuli, to transform energy from the environment into growth and reproduction – are all abilities that range widely between species, and yet, we call them the same ability. Chickens laying eggs, apples falling from trees, women giving birth with wires attached to their bodies, protists dividing themselves in half – we call each of these reproduction.
But can we really call these the same ability? And if so, how far are we willing to extend our interpretation of what it means to reproduce, and in turn, what it means to be alive?
Consider fire. Fire grows, responds to its environment, and transforms energy; is fire alive?
Consider a barrel of wine, aging. Cheese. A hair follicle, saliva, or any DNA sample. A fossil. A kidney in a freezer.
There’s no doubt that the definition of life is as murky and messy as Aristotle’s early model of the solar system, with the Earth at the center, and all the planets revolving around Earth in irregular curlicue orbits. So, consider a fifth family of life: one that includes the car. (Busses, trains, motorized ships, and even computers may be included in this family, as well). Consider the car alive; seriously, consider this ridiculous notion. Because, honestly, is it really so ridiculous? In terms of reproduction, few species, over the past century, have seen their population multiply like cars. In terms of responding to stimuli, cars not only respond, but depend totally on stimuli to function. And in terms of transforming energy, of course cars consume gasoline and excrete exhaust.
But cars don’t have a brain, you say. Neither do plants.
But cars don’t have cells, you say. Neither do viruses.
But cars do not control themselves, you say. They depend on people, you say. And yet, if you were to go for a walk down the street right now, you would not control any of the cars you saw. And even if you were to get into a car, and go for a drive, you would control only that one car. People do not control cars any more than they control each other. (And driverless cars? That’s a whole other discussion).
In cities, this often makes human beings second-class species. While the cars run the streets, people are relegated to the sidewalks. To cross the road, we have to wait for the cars to stop, and then as a token of our gratitude, nod our heads in thanks, submissively, at the cars that have slowed, mercifully, to let us pass.
And yet, there is reason for optimism: evidence that humans are adapting to sharing their urban habitat with this new family of life. We have become aware – almost all of us have – that cars transform the environment in ways that do not bode well for our species’ long-term health. We have made efforts to limit our dependency on cars with improvements in public transportation, and we have developed new strategies, like traffic calming, the gas tax, and tolls, that are intended in theory to de-incentivize driving in the same way that fish, if they were intelligent, might develop a series of strategies that would de-incentivize biting bait on a hook. Yes, call a spade a spade, a car a creature of the road: there is reason for optimism.