The long days of late June with their twilight lingering until after 10 PM have given way to real July. Hot, dry July with sunny afternoons that build the towering cumulus thunderheads, gradually merging with one another and growing darker and darker on their bottoms so that by late afternoon they obscure large chunks of sky with the so-far unfulfilled threat of rain.
In cities, this sort of weather brews tension. Here at the lake, we hope for a show of flash and bang that we can watch rolling in from the West.
In the afternoons, when the heat and the clouds are growing, we take the dog for a walk along the shallow stretches of sandy shore (more or less involuntary alliteration) where the insects and the minnows have gathered. You can see a lot by just observing. The strategy of biology is laid out in more clearly than in any textbook – as Edwin Land said, “anything worth doing is worth doing to excess.” In the natural world, reproduction is absolutely worth doing. Hordes of tiny fish and hordes of tiny insects thrive in the warm shallow water. At the end of June, you literally couldn’t hope to count them. Just ten days later, there are still crowds but the number of individuals has probably dropped by a factor of ten while the size of the individuals has at least doubled.
In the long term, any pair of parents achieves success by replacing two individuals who reproduce and will then die with two more who will do the same. All the rest of the offspring are created in order to compensate for pre-reproductive mortality. The more complex the ecosystem, the more effectively it can auto-regulate to maintain its sub-populations within viable limits. Some years, fewer fish and more bugs and some years more fish and fewer bugs, but always there are some fish and some bugs.
Do humans have an innate response that will down-regulate populations in over-crowded settings? We haven’t seen much convincing evidence for it yet, but we need to think seriously about it. What’s the optimal human population for this planet? How could we sit down and figure that out? Answering those questions would require us to consider what we really value, and where we fit in the overall scheme of things.
That’s what I think about while the dog chases minnows in the shallow weedy water.