Tuesday, November 12, 2013

Thermal ranges and microbiota

Temperature has been much in the news over the past few years. It's becoming apparent that no matter how much clamor the deeply misinformed far-right climate change deniers raise about it in the United States, the story is here to stay.  

We live within an extraordinarily tiny range of temperatures; a slice, so to speak, from the spectrum, as though we were a pair of eyes only able to see orange. Living organisms around us, in the meantime, have found ways to colonize a much wider (although still relatively tiny) range of temperatures; microbes (and, let's be fair, some larger organisms) are able to fully function from temperatures near freezing all the way up—in the case of microbes—to temperatures in excess of the boiling point of water. These creatures are called thermophilic organisms; and their presence in underground high-temperature waters, such as those found deep in South African diamond mines and at the mouths of undersea thermal vents, suggests that thermophilic microbe may well have been among the first life that evolved on earth, perhaps even the very first life.

Our presumptions about the temperature ranges and conditions life can function in have been progressively challenged over the past fifty years; microbes, it seems, can probably even survive the condition of interstellar space without losing the ability the thrive and reproduce if they make it to a new solar system. While the idea of intergalactic travel seems, today, impossibly remote, it seems to be reasonably certain that among the trillions of galaxies, ours cannot be the only one that supports life.

Life on the smallest scales displays a resiliency absent in larger forms. The conditions it needs to support it are, for one, far more focused. Nutrients can be derived from far more basic building blocks—even molecular ones— with far less obstacles to finding and assimilating them. The difficulty of procuring food, it might be said, is roughly inverse in proportion to size. Small creatures need little food; large ones need lots of it. Microbes, in this sense, have the decided edge in the competition for energy resources. They can live in marginal circumstances, subsisting on marginal resources; larger creatures need far more tailored environments, built on far more complex food pyramids. So microbes have the advantage not only in terms of temperature, but also scale.

We humans see ourselves as flexible in terms of temperature and scale; imagine ourselves as supremely adaptable to a wide range of environments. Yet microbes outperform us handily in this area, and they do so without any of the specialized equipment we require when operating outside our comfort zone. Speaking as regards to suitable habitat, we're actually confined to an incredibly narrow range of circumstances; even a tiny step outside them causes us to resort to protective clothing and vehicles. 

We think we rule the earth; but in reality the bacteria do. They live and reproduce in massive numbers in places we will never go; places deep in the earth, where life has found what are, to us, completely alien paths to survival. They share the same DNA, but their destinies diverged from ours billions of years ago.

Even then, some of them have developed novel approaches to DNA and reproduction itself; which shows you just how incredibly creative archaic microbes can be.

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