Day 36: Is Plastic the New Oxygen?

Imagine that it was possible for you to observe the primordial Earth, a little over 2 billion years ago, when plant life first began to emerge. Up until then, all life depended on chemicals in the environment, such as hydrogen sulfide from volcanic vents, or simple hydrocarbons such as methane. Along comes this new form of life that can get its energy from the sun using photosynthesis. No longer tied to certain locations where they could find food, they could spread to any location that received sunlight, and populations of photosynthetic life forms explode.

This new life form came with a price, though: these creatures emitted a highly corrosive chemical as a waste product of photosynthesis: oxygen.

That’s right: before photosynthesis, there was little oxygen in the atmosphere. What little there was reacted with metals such iron, corroding it to oxides like rust.

By any definition of the word, plants were polluting the atmosphere. From that definition:

The presence in or introduction into the environment of a substance or thing that has harmful or poisonous effects.

To early Earth, oxygen was a pollutant. In fact, geologists use the sudden increase of oxidized metals in the Earth’s crust to determine when the emergence of photosynthetic life occurred. But it was exactly this sort of “pollution” that enabled the rise of a different kind of life: animals that breathed oxygen to “burn” carbohydrates and fat for energy.

Fast-forward to the present day. Human life has left its mark on the planet, and have created two materials that will likely be part of the geologic record: concrete and plastic. Concrete is relatively inert, but plastic is made from hydrocarbons, and could be a source of energy. Amazingly, scientists have already found a bacterium that can digest plastic for energy. That’s pretty amazing, considering that plastic has only existed for a century or so, which is infinitesimal on an evolutionary timescale.

So if it were possible to be present when it was happening, who would have ever thought at that time that the emergence of highly-corrosive oxygen pollution in primordial times would ever be a good thing? Yet today we certainly feel that it was, as it enabled the rise of new life forms (such as us!).

So I have to wonder: is it possible that the emergence of plastic as a nearly ubiquitous presence in the environment might result in amazing new forms of life, as happened with the addition of oxygen to the environment? It seems just as far-fetched as considering the introduction of a corrosive element would be a positive change.

Of course, we’re talking millions and millions of years, but nature has done stranger things in that kind of time frame.Such evolution would require that humans would continue to crank out plastic and dump it into the ocean for millions of years, or life that depends on consuming plastics would quickly hit a dead end.

Don’t get me wrong: I’m not advocating for plastic waste in the hope of some wonderful new life form. I feel very strongly that we should reduce out plastic usage, and recycle/reuse as much as possible. And we should be doing everything we can to limit the spread of waste plastic into the environment.

But it’s something to think about.