- Why the Last People on Earth Will Eat Sugar Cane and Corn – The lack of CO2 in the atmosphere will pretty much take out Earth's ecosystem. Trees will go first, then most flowering plants, and eventually the world will de-green itself almost entirely, taking most of the animals with it. But not necessarily human animals. Unlike most other animals on Earth, humans are able to pick and choose which food we subsist on — and we could cultivate one staple and one sweet to keep the last humans on Earth alive.
There are several types of of photosynthesis in plants. Most plants just randomly grab carbon dioxide from the atmosphere. There have been studies done on whether the increase in carbon dioxide in the atmosphere is allowing them to grow more productively. The answer, for the most part, is not really. There were types of plants that weren't even included in the studies, types that had a special process which made the amount of carbon dioxide increase irrelevant.
All plants have an enzyme that collects carbon dioxide, but puzzlingly, that enzyme also collects oxygen. This is useless to the plant, but since there's no scarcity of carbon dioxide, the inefficiency doesn't do any harm to the plant. Some plants, though, have another enzyme, PEP-carboxylase, which occupies a special mesophyll cell in the plant. The enzyme grabs only carbon dioxide, and the cell acts a pump, concentrating the gas before turning it over to the more common enzyme. Scientists are confused as to why these special structures are in place, since there's no reason to put energy into conserving a resource that isn't scarce in the first place. It's an energy drain that make the plants less fit. And really, only a few plants have this special process. A few African grasses have developed the other enzyme. They'll be useless. But humanity lucked out that it's current ubiquitous crop, corn, and its favorite drug, sugar cane, both happen to have this process in place. They're the apocalypse plants. They're going to be the last ones to go.
They will go, though, along with everything else on Earth. The oceans will evaporate and steam off into space. The atmosphere will follow suit. By, conservatively, the year one billion, the Earth won't look much different from Mars or Mercury. If microbes are alive on its surface, they'll have to be tough microbes. Let's hope that by that time we'll have figured out how to go somewhere with a more functional atmosphere. It's amazing, though, that we know what the last humans on Earth – assuming humanity makes it that far – will be eating as they watch their world die around them. These aren't just the food of the future. They're the food of the end of the future.
Tags: research food SF