(HOST) It may not come as a surprise to hear that commentator Ted Levin’s summer reading list is a little bit unusual – and that this year he’s decided to learn more about life at the microscopic level.
(LEVIN) Our knowledge of the world has changed dramatically over the past half century. In the 1950s biologists recognized two kingdoms: plant and animal.
Then, microbiologists decided that single-celled organisms – amoeba, paramecium, bacteria, algae, and so forth – were so different from the multicellular world that they warranted their own kingdom called Protista. Now, by virtue of molecular genetics, all life is divided into three great divisions: Bacteria, Archaea, and Eucarya.
The first two are entirely made up of bacteria (single-celled organisms without a cell nucleus), whose abundance and diversity far exceeds that of Eucarya, of which animals, plants, and fungi are the only multicellular members among seven subdivisions of single-celled creatures, each with a cell nucleus.
After finishing the first two books on my summer reading list, Full House, by Stephan J. Gould and The Third Chimpanzee, by Jared Diamond, I’m now convinced that we live in a world of bacteria, and may in fact be little more than organized bacteria ourselves.
Let me explain. The range of differences between the subdivisions of Bacteria is as great as those between animals and plants. And why not. The first two billion years of the history of life is a history of bacteria. In fact, photosynthetic bacteria – what I grew up calling blue-green algae – made our atmosphere breathable. Without their activity life as we know it would not exist.
Bacteria are everywhere and thriving. The number of E. coli (the very same bacteria that can cause illness) in a single human G.I. tract exceeds the total number of people that have ever lived. And a square centimeter of human skin harbors more than100,000 microbes.
Where there’s life there’s bacteria. They even live on the fringes of the planet, where nothing else can live. They live in boiling hotpots in Yellowstone National Park where temperatures rising from the depths of the earth exceed 480 degrees Fahrenheit. They live in sea vents 10,000 feet below the surface of the ocean where water temperature under extreme pressure reaches 600 degrees Fahrenheit.
A good case could be made that we live in the Age of Bacteria, not the Age of Mammals, an Age that began three and a half billion years ago and still bubbles along.
Perhaps you remember hearing the terms chloroplast and mitochondria in high school biology class. Chloroplasts are found in the cells of photosynthesizing plants. They capture sunlight. Mitochondria are the “energy factories” of all cells. Both look like small bacteria. Both function like small bacteria. Both have their own independent DNA programs. And both were in fact independent bacteria that coalesced into the first nucleated, single-celled organisms. Which begot multicellular creatures. And in time begot us.
Ted Levin is a writer, photographer and winner of the 2004 Burroughs Medal for Nature Writing.