2006 : WHAT IS YOUR DANGEROUS IDEA?

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Biologist, Distinguished University Professor, UMass, Amherst; Coauthor (with Dorion Sagan), Acquiring Genomes: A Theory of the Origins of Species
Bacteria are us

What is my dangerous idea? Although arcane, evidence for this dangerous concept is overwhelming; I have collected clues from many sources. Reminiscent of Oscar Wilde's claim that "even true things can be proved" I predict that the scientific gatekeepers in academia eventually will be forced to permit this dangerous idea to become widely accepted. What is it?

Our sensibilities, our perceptions that register through our sense organ cells evolved directly from our bacterial ancestors. Signals in the environment: light impinging on the eye's retina, taste on the buds of the tongue, odor through the nose, sound in the ear are translated to nervous impulses by extensions of sensory cells called cilia. We, like all other mammals, including our apish brothers, have taste-bud cilia, inner ear cilia, nasal passage cilia that detect odors. We distinguish savory from sweet, birdsong from whalesong, drumbeats from thunder. With our eyes closed, we detect the light of the rising sun and and feel the vibrations of the drums. These abilities to sense our surroundings, a heritage that preceded the evolution of all primates, indeed, all animals, by use of specialized cilia at the tips of sensory cells, and the existence of the cilia in the tails of sperm, come from one kind of our bacterial ancestors. Which? Those of our bacterial ancestors that became cilia. We owe our sensitivity to a loving touch, the scent of lavender , the taste of a salted nut or vinaigrette, a police-cruiser siren, or glimpse of brilliant starlight to our sensory cells. We owe the chemical attraction of the sperm as its tail impels it to swim toward the egg, even the moss plant sperm, to its cilia. The dangerous idea is that the cilia evolved from hyperactive bacteria. Bacterial ancestors swam toward food and away from noxious gases, they moved up to the well-lit waters at the surface of the pond. They were startled when, in a crowd, some relative bumped them. These bacterial ancestors that never slept, avoided water too hot or too salty. They still do.

Why is the concept that our sensitivities evolved directly from swimming bacterial ancestors of the sensory cilia so dangerous?

Several reasons: we would be forced to admit that bacteria are conscious, that they are sensitive to stimuli in their environment and behave accordingly. We would have to accept that bacteria, touted to be our enemies, are not merely neutral or friendly but that they are us. They are direct ancestors of our most sensitive body parts. Our culture's terminology about bacteria is that of warfare: they are germs to be destroyed and forever vanquished, bacterial enemies make toxins that poison us. We load our soaps with antibacterials that kill on contact, stomach ulcers are now agreed to be caused by bacterial infection. Even if some admit the existence of "good" bacteria in soil or probiotic food like yogurt few of us tolerate the dangerous notion that human sperm tails and sensitive cells of nasal passages lined with waving cilia, are former bacteria. If this dangerous idea becomes widespread it follows that we humans must agree that even before our evolution as animals we have hated and tried to kill our own ancestors. Again, we have seen the enemy, indeed, and, as usual, it is us. Social interactions of sensitive bacteria, then, not God, made us who were are today.