Sunshine, Sweat and Purple Flowers

Lately, the days are warm—so wonderfully warm that if feels like a miracle after the cool, wet summers we’ve had here in England in recent years. There are butterflies everywhere. The grasses are high, the meadowsweet is fading into seed and there are small green berries forming on the brambles.

The colour palette for these late July days is deep pink to purple, ranging from willowherb and loosestrife through to thistles, knapweed, betony and purple vetch.

I am still taking a long, brisk walk in the early afternoons, but today, as the hot sun beat down out of a cloudless sky I found myself slowing down a little and even wondering if I should change my timetable and walk in the cool of evening instead.

Not that I am a stranger to the heat. I have lived in the tropics and in California and in rural Texas and the only times when I ever found it too hot to go for walks were those searing summer days in Melbourne when the temperatures soared above the century and every gust of the merciless north wind was like opening the door of a hot oven. To take any vigorous exercise in those conditions would have been to court heatstroke and even I am not that silly.

But today, as I paused in the shade to touch the bark of my favourite oak tree and felt the salty sweat trickling down my face, I thought about the evolutionary gift of homeostasis that Nature has bestowed on all warm-blooded organisms like us. It’s pretty amazing when you think about it—a precious gift, in fact. From arctic cold to equatorial heat, we can adjust our lives accordingly and keep our body temperatures pretty much constant at all times. And that is something to feel very grateful about.

It is also salutary, I believe, to reflect that the principle of homeostasis applies to many, many other things in the universe. It’s another case of ‘as above, so below.’ As James Lovelock demonstrated, with his famous Daisyworld experiment, Earth herself operates that way. Like any other living organism, she has to keep her temperature within a certain range and she has a number of ways to achieve that but her ways are not limitless. Like us, her adaptability has limits. Gaia’s temperature regulation  is a mechanism that has worked for billions of years—until human beings came along and started messing with the system. And now we have anthropogenic climate change. If our precious planet ends up dying of heatstroke because we were too silly to change our ways, we can’t say we were never warned.