The Human Race to the Future: What Could Happen - and What to Do [2014 edition] by Berleant Daniel

Author:Berleant, Daniel [Berleant, Daniel]
Language: eng
Format: epub
Publisher: Lifeboat Foundation
Published: 2014-01-31T22:00:00+00:00

Teeming cities

A twenty-person colony is not a teeming city, though it may seem teeming, what with crowding into living space that is scarce owing to the difficulty and expense of building each new square foot of high tech, hermetically sealed, oxygenated habitat for housing colonists and producing food. Expensive or not, square footage will need to be constructed because, if all goes well, children will be born and the colony will grow.

Natural growth rates for human societies vary, but are generally under 5% per year. Overall, world population is currently growing by about 1% per year. Let’s assume for a moment that our Martian colony experiences the same growth rate, 1% per year. How long do you think it would take for the original twenty person colony to expand into a vigorous town of a thousand people? 100 years? 500? 1,000? 5,000? The answer can be readily found with a calculator or spreadsheet: just 394 years. How long for the colony to become 10 million Martians — a teeming city or, more likely, several? Take a moment to guess. Here is the answer, spelled backwards so you don’t read it accidentally. .sraey neves ythgie dnasuoth eno erem A

Why stop at 10 million? Population growth on Earth didn't, and there is no reason why it would on Mars either. A burning question then becomes when Mars will pass its capacity and tip into overpopulation. If capacity is 10 billion people, er, Martians, it would pass that point, starting from the original 20 colonists, in only 2,014 years.

Here on Earth, the road to 10 billion has already taken a lot longer than that. How long? The question is unanswerable because we don’t know when the process started. But perhaps a rough starting point could be assigned based on what we do know. For example, we know that the surprisingly low genetic diversity of humans (compared to most species) suggests we “began” (in a sense) relatively recently and have not had time to accumulate the mutations needed for much genetic diversity. The Toba supervolcano eruption about 73,000 years ago has been proposed as this starting point, by causing a multi-year volcanic winter from throwing so much dust and smoke into the atmosphere. On this view, populations of protohumans were devastated, leaving only a small community alive. That group then expanded, sweeping across the world. Adding in a modest amount of Neanderthal blood (up to 4% is typical), and factoring in the evolutionary changes since then, we get the human race.

Whether human colonization of Earth began 73,000 years ago or at some other time, it is clearly taking a lot longer to reach a population of 10 billion here on Earth than it would on Mars, given even a modest 1% annual population growth. This is due to the scourge of infectious disease — “pestilence” — as well as other privations. Without those curbs, populations have been often observed to expand at rates in the 3–4% per year range. So our 1% growth rate assumption for Mars may be too low.

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