Sometime earlier this month, the human population is reckoned to have reached the milestone of 8 billion. So, congratulations to us, I guess?
We humans dominate the planet. The majority of Earth’s good land has been taken over by us. We’ve increased the amount of carbon dioxide in the atmosphere by 50%. The mass of human bodies is far larger than that of all of the wild land mammals combined.
It’s happened fast. The 4 billion milestone was also crossed in my lifetime, and I’m not yet a senior citizen.
The average quality of life for humans has continued to improve, even as the population grows. So that’s good. But it doesn’t tell me much of anything about the optimal human population. It just tells me that the combination of our improving technology, use of the Earth’s resources, and various political developments has, so far, at least slightly outpaced any hypothetical negative effects of population growth.
These trends can’t continue indefinitely. Whatever the maximum number of humans that can comfortably live together on Earth might be, it is a finite number. And it’s not so large that it can’t be reached in the not-too-distant future.
But despite the clearly increasing population, it seems to have become more fashionable to express concern about the possibility of underpopulation than of overpopulation.
(I’m not referring to the possibility that some disaster unrelated to population might do away with most or all of the humans. That might happen, but let’s optimistically assume it doesn’t.)
I thought about addressing a list of the usual arguments as to why overpopulation is good and/or impossible, or why a declining population is bad and/or a real threat. I find almost all of them to be unconvincing at best. (Like, your biggest concern about a declining population is that we might need a new strategy for elder care? Seriously? That’s the best you can do?)
But I’m lazy, so I’ll just briefly discuss the one I’ve seen a lot lately, which is the observation that, in some countries, the birth rate has fallen below replacement level. This birth rate decline is mainly due to people choosing to have fewer children, though biological reasons (declining sperm count, whatever) might get some of the blame. I’ll charitably assume the fear is that this phenomenon will spread to all groups of humans, ultimately causing the extinction of the species.
I don’t for a moment think that a declining birth rate is anything to worry about. It may well cause the population to dip, but the dip will only be temporary. Even as most people choose to have fewer children, there will still be some who want to have lots of children, and are able to do so. Both the desire and the ability to procreate are genetically influenced. Thanks to this pro-procreation minority, genes for fecundity will then be over-represented in the next generation. Such genes will spread like wildfire through a population that has room to grow. The problem is self-correcting.
But this also implies that whatever ultimately curtails population growth will be something else. Like mass starvation. Or denial of reproductive freedom. Or a small tax incentive to help stabilize the population. Scary, but perhaps inevitable.
Maybe I’m biased, but I root for humans, and I want there to be a lot of us. I just question the wisdom of trying to pack us all onto the planet at the same time. I bet we could do better by spreading the species out over time, so I’d rather see us try to figure out how to survive and thrive in the long term.