Density is in our Blood

Scientific American presents evidence that "high density living" is hardwired in humankind, and as populations grow, density increases.

The report, produced by a team of anthropologists and ecologists, studied 339 hunter-gatherer societies, and found that people tend to live more densely as their populations grow. In fact, "...(f)or every doubling of population, the home ranges of hunter-gatherer groups increased by only 70 percent."

Reporter Tim De Chant says this evidence is very significant:

"Every additional person requires less land than the previous one. That's an important statement. Not only does it say we're hardwired for density, it also says a group becomes 15 percent more efficient at extracting resources from the land every time their population doubles."

Full Story: Hunter-Gatherers Show Human Populations Are Hardwired for Density



'Populations' don't exist in a vacuum

The inference of 'hardwired for density' is awfully ambitious. One has to wonder what competition for resources by adjoining populations do to restrict home ranges - it might be instructive to look at any similar studies of other species - say ants or large carnivores. I'd be willing to wager there would be at least some evidence that hunting-gathering species are only as efficient as they are compelled to be by close competition... (why not 'cherry-pick' the best of what's out there if the whole world is yours for the picking?)

Hunter-Gatherers Live At Low Density

I am in favor of high urban densities, but I am afraid that this study reached absurd conclusions.

When humans evolved as hunter-gatherers, they lived at low densities, typically about 1 person per square mile, because they needed a large range to gather enough food for each person. This is when we were hard-wired by evolution.

In a study of existing hunter-gatherer societies, it is not surprising that density gets higher as population increases. These societies generally have a limited amount of free land around them, so they cannot expand their territories enough to keep their densities down to the optimum level for gathering food, as people were able to do as our species evolved.

Nevertheless, these existing hunter-gatherer societies live at much lower densities than urban societies. The densities in the study vary from .56 to .316 square kilometers per person. The fact that density increases to 3 per square kilometer as their population increases certainly does not prove that humans are hardwired for urban densities.

My own theory is that early human societies spread out to hunt and gather during most of the year, but periodically came together in larger groups. Coming together in this way was adaptive, because it created a larger gene pool for mating, which makes it less likely for children to have genetic defects. People who were attracted to these dense temporary settlements were more likely to have healthy children, so the genes that attract us to these sorts of settlements spread through the gene pool, hard-wiring us to like density.

Any theory about why we are hard-wired for density has to involve this sort of evolutionary advantage. The theory in this article does not do this, and it is completely inadequate as evolutionary psychology.

Charles Siegel

You are my density.

One gets tired of all these articles that conclude 'because I like density, you do too! or 'gosh, I like dense neighborhoods so therefore lets build nothing but dense neighborhoods!!! *heart!!!!*


This is not to say that inefficient land uses are just ducky.



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