Astrobiology Magazine: In Microcosmos, you talk about bacterial intelligence. A lot of people have trouble with that concept because -

Lynn Margulis: - Well, they haven't been to parties with adolescents -

AM:- they tend to think intelligence comes from brains.

LM:I know they do. They're wrong.

AM:Can you explain how you view bacteria as being intelligent?

LM:If you look up consciousness in the dictionary, it says, "awareness of the world around you," and that's because you lose it somehow when you become unconscious, right? Well, you can show that microorganisms, or bacteria, are certainly conscious. They will orient themselves, they will work together to make structures. They'll do a lot of things. This ability to respond specifically to the environment and to act creatively, in the sense that that precise action has never been taken before, is a property of life. Of course, it has to be moving life, or you can't tell. You can't tell if a plant is thinking, but in organisms that move, you can tell their intelligence.

For example, take Foraminifera - they're single-celled sea creatures, protoctists. The Egyptian pyramids are built of their shells. A colleague of mine put one of these forams in a dish with a small crustacean animal, like a water flea. He was going to watch the crustacean eat the foram. The foram's a single cell, and smaller, right? And he saw the foram kill, trap, and completely destroy and eat the animal. He's got beautiful movies of it. So that group of organisms not only can eat animals, but they can make hunting towers, and they can hunt from the top of the towers.

There's a group of them, called agglutinating forams, these have offspring that look exactly like the parent, with multi colors. But every generation they construct their coloration from pebbles. This single-celled blob - it would look to you like a blob of snot, probably - can pick up pebbles of the different colors. You have to have some red ones and some white ones and some black ones in order to get an offspring that looks like a parent.

They will make appropriate choices such that when you see the offspring next to the parent, it looks like they just came about by dividing in half. You can't believe that the newer one, the offspring one, was naked, and then it spent a lot of time plastering and remolding and rearranging pebbles on the surface of itself, so that it now looks indistinguishable from its parent. Those kinds of activities are rampant.

People think that if you can't talk, you can't be intelligent. But you know that's not true if you have a dog. You can communicate with them without talking. If you define intelligence as speaking American English, well maybe they're not. But if you define it in the much more broad sense of behaviors that are modified on the individual level, that involve choice and change and response to the environment, there's every bit of evidence that intelligence is a property of life from the very beginning. It's been modified, of course, and changed and amplified, even, but it's an intrinsic property of cells.

AM:You support the Gaia theory, the view that Earth's biosphere is a living superorganism that's capable of self-regulation.

LM:That's what James Lovelock, who developed the Gaia theory, might say, and I disagree with him about the word "organism" in there, super or not. Why? Because no single organism is known that breathes in its spent gasses and eat its own waste, drinks its own liquid waste, and survives. An organism is too small, in principle, the way one person is not a family, and one family is not a city, to be the self-regulating system that Gaia refers to. So I would replace the word "organism," or "superorganism" with, say, "ecosystem," or "set of communities that make an ecosystem."

The original Gaia hypothesis was that Earth was a physiological, self-regulating system with respect to temperature, reactive gas composition and acidity-alkalinity. Because if that system were destroyed on the surface of the Earth, then the Earth would become completely reflective of its cosmic background. It would just be an interpolation between Mars and Venus, like it probably started.

AM:That's a good lead-in to the next question I wanted to ask you. What does the Gaia theory predict about the likelihood of finding evidence for life on Mars?

LM:Gaia from a distance sees no life on Mars. Jim Lovelock and I wrote a paper in 1974 that said that from a Gaian point of view there is no life on Mars, you're wasting your time to go. We said the atmosphere was what you would expect of a sort of a steady-state composition at this distance from the sun, that there was no evidence from space that the living phenomenon was occurring on Mars, the way there is from space that it is occurring on the Earth.

I would say that that would still be true, unless there was some form of deep-freeze dormant life. If there's life on Mars, it's got to be such that it does not influence the measurable aspects of the environment. I would still bet there isn't any, but I certainly can't preclude the idea that there's dormant, deep life, cave life, quiet life, that just doesn't have a planetary-level effect because it's so sparse. I can't preclude that, but I think it's very doubtful.

At any rate, the Gaia hypothesis I think is totally useful. It was invented as an explanation of the differences between Mars, Venus and Earth, and it does give us fantastic criteria. If you go to Jupiter and see hydrogen, methane, ammonia, water, hydrogen sulfide, those are all chemically reduced gasses compatible with each other. But if you see, in the presence of overwhelming chemically reduced gasses, even a trace of oxygen or carbon dioxide, you don't have a test for life, but you have a putative indication of life.

It tells you, Get over there and do something about it, because that's what you'd expect of a living system. It leads to environmental inconsistencies. That's one of the beautiful things about the Gaia hypothesis: you don't have to know anything else, but you can detect a chemical anomaly, and then use it as a criterion for further exploration.

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