Halfway through my PhD viva, my external examiner asked me to define a psychrophile.
Given my thesis was about the microbes living on glaciers, it was a fair question.
I quickly trotted out an undergraduate textbook answer: An organism showing adaptations which permit life in the cold. Coupled with a sketch graph of cardinal temperatures of psychrophiles versus mesophiles, the examiner seemed satisfied.
Of course, the nature of these adaptations have been open to debate, and Ricardo Cavicchioli recently wrote an insightful article for The ISME Journal which challenges the very notion of psychrophily.
But what are the psychropaths?
Investigating microbial life on glaciers has become an enduring research interest of mine which has occupied most days of my life since that question.
Sometimes the microbes living on glaciers are described as cryophiles, rather than psychrophiles. The terminology makes no odds. Because many of the most successful microbes on glaciers are contributing to the destruction of their own habitat.
Their growth darkens ice and snow, increasing melt rates. Or they produce a powerful greenhouse gas in the form of methane. These organisms colonise glaciers the world over.
Can we really fit the notion of loving, or liking cold and ice- as expressed by the Greek philos to these organisms which engineer the destruction of their own ecosystems? I doubt it. Pathology fits better: I’d argue they have psychropathic tendencies.
It explains all those ice axes too.