These marshes are awash with invisible chemistry

If I set aside the rag-winged rooks and moulting lapwings, and forget the storms that this land has just endured, the morning seems utterly still. I stand to watch a long flotilla of cumulus over the marsh, as beautiful and unmoving as sail ships becalmed in doldrums. There is so little breeze that neither foreground nettle nor the red-tinged Yorkshire fog beyond so much as stirs.

Even with my coarse senses, however, I know that this rain-washed stillness is volatile and densely scented. There is a deer nudging through the reeds that I shall never see, because it navigates by smell.

There is a foul blast of musk that its owner left last night on the path and it’s now so clogged with stink you’d think that Claxton had no other chemistry but that of fox. There are moths here that can follow pheromone trails to potential mates across 8km of intervening ground. And bumblebees of four species, threading the dog rose in our garden, add to the flowers their own micro-trace of scent from their feet and bodies that inform other bees exactly which blooms have been visited and drained.

Finally there was a dead vole. Who knows what necrotic vapour winds through the square of light above where it lies on the path, but black ants are already prospecting its corpse. More than any other, these insects allow us to reflect upon a chemical realm we can seldom know empirically. Ants, which have a total biomass equal to all humanity, are governed by it. They lay pheromone trails that their sisters can follow, and the man who first researched these invisible tramlines, EO Wilson, proposed that a single microgram of pheromone, if laid with maximum efficiency, would be enough to send billions of ants three times round our planet.

The space I look across and view as clear air is in truth a cataract of molecules guiding life in all its trades. Yet that entire grand bazaar of old summer chemistry is all blended to me now and I can pick out just one: the first whiff of autumn.

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