Evolving Thoughts

Evolution, culture, philosophy and chocolate! John Wilkins' continuing struggle to come to terms with impermanence... "Humanus sum, nihil humanum a me alienum puto" - Terence

Sunday, May 07, 2006

The evolution of lawns

PZ Noun laments the need to mow his lawn. So do we all (I have a Darwinian view of gardening - anything that can survive my tender ministrations deserves to be there. I once killed a cactus by under-watering. I have a shriveled black thumb). But nobody asks the obvious question: why do we have lawns at all?

I have a theory. It is mine (ahem). Consider what lawns are - they are composed of early colonising plants that typically grow in patches of recently cleared ground. Later, longer grasses take over, and if the conditions are right, and there are no grazing animals, trees and forests. So it takes a considerable amount of energy to maintain a lawn. Why would we do this?

The English had lawns of camomile and herbs in the middle ages. Grass lawns began as part of the seventeenth century fashion, out of Italy, France and England, of bordered and hedged gardens, which were made by the rich aristocracy, who had plenty of land around their manors and palaces. A mown lawn was an indicator of wealth, disposable land, and servants to do the scything before mowers were invented in 1830. So it became the fashion for the middle classes, who were on the rise at the time in terms of wealth, to emulate the aristocracy. Lawns became particularly an English passion, and from there to America and the Commonwealth.

Why would we have lawns? To display our wealth and status. In other words, to behave as social dominance behaving apes. And the use of land is particularly interesting. We evolved as territorial nomads, not as landholders. What made us landholders was the coevolution of agriculture. When you spent most of your time sowing and nurturing crops, you needed to defend your territory (Rindos 1984), which gave rise to a warrior class from whom the rulers were chosen or arose through might and alliances.

One of the things that such wealthy rulers do is display their status through conspicuous consumption. Lawns were a case of "honest advertising" in that respect. Having land meant that you controlled power, such as military might, and could waste perfectly useful crop fields for a useless product that had nothing to recommend it other than it looked good.

Lawns also take an inordinate amount of water. In arid countries and places like Australia and the south western United States, to waste that much water is another signal of wealth. Of course, this requires that the signal is both differentially available (if everyone can grow one, it's not that much of a status symbol), and of course that the water is freely available. Unfortunately, now that the fashion is ensconced in our culture, we can't continue to do this, so the social selection pressure with rise to have them to display wealth. So something is going to have to give.

And none of that even begins to address the problem of ecosystems for native animals. PZ Thingy needs to grow his prairie.

Rindos, David (1984), The origins of agriculture: an evolutionary perspective. Orlando: Academic Press.

Late edit - south eastern to south western, as per reader's edit in comments.