In the 1960’s, a chemist named James Lovelock was invited by NASA to help develop instruments that could detect signs of life on Mars. Lovelock came up with the idea of screening the gases in Mar’s atmosphere for signs that their concentrations were being affected in ways consistent with life.
On Earth, for example, the atmosphere is composed of about 77 percent nitrogen, 21 percent oxygen, and trace amounts of other gases, most notably carbon dioxide and methane. These gases are used and absorbed by plants and animals and then remade and recirculated back into the atmosphere. Mars, on the other hand, has an atmosphere that is almost 95 percent carbon dioxide.
The stark contrasts between the two planets suggested to Lovelock that Mars couldn’t possibly harbor any type of life or that if it did, it was in the very distant past. Chemically, Mars was a dead planet, and to Lovelock, this meant that it had to be biologically dead as well.
If there was life on Mars, it would leave a chemical signature that could be detected from Earth, Lovelock reasoned. The cumulative actions of countless organisms would over time change the composition of gases in the atmosphere and these changes would be visible from space. This kind of thinking lead Lovelock to a sudden realization. Recalling it years later, Lovelock wrote:
“I was in a small room on the top floor of a building at the Jet Propulsion Laboratory in Pasadena, California…An awesome thought came to me. The Earth’s atmosphere was an extraordinary and unstable mixture of gases, yet I knew that it was constant in composition over quite long periods of time. Could it be that life on Earth not only made the atmosphere, but also regulated it – keeping it at a constant composition, and at a level favorable for organisms?”
Lovelock discussed his idea with his neighbor, the novelist William Golding, and it was Golding who suggested Lovelock’s new theory be named “Gaia,” after the Greek goddess of the Earth.
When it was first proposed, Gaia theory appealed to environmentalist but was largely dismissed by the scientific community. Critics said the theory was unscientific and that it was teleological, that it was proposing that there be some kind of planet-wide consciousness at work.
Other critics, like Richard Dawkins and Ford Doolittle, argued that Gaia theory was at odds with Darwinian evolution. Instead of having organisms simply adapt to their environment, Gaia theory was saying that organisms could actually change it or even control it. In 1982, Dawkins claimed that “there was no way for evolution by natural selection to lead to altruism on a Global scale.”
Gaia theory was also at odds with one of Dawkins’ own theories. In 1976, Dawkins published a book entitled “The Selfish Gene” in which he argued that evolution acts not on individual organisms, but on their genes. Organisms were mere vehicles that genes used to replicate themselves. Those genes that helped an organism survive and reproduce also improved their own chances of being passed on and so most of the time successful genes also benefited the organism. For Dawkins, life was a constant war: individuals within a species were competing with one another as well as with the members of other species. What they definitely were not doing, in Dawkins’ view, was working together for the common good of the planet.
In response to his critics, Lovelock teamed up with Andrew Watson and developed a computer model called “Daisyworld.”
Daisyworld was a simulation of an Earth-like planet orbiting a young, Sun-like star. The only form of life on the planet were daisies, of which there were two varieties: black and white. White daisies had white flowers that reflected light and black daisies had black flowers that absorbed light. Thus, a planet covered in white daisies was cooler than one covered in black daisies.
In the beginning, when the young star is just starting to warm up, the planet is covered mostly in black daisies. As the planet continues to warm, however, more white flowers begin to bloom. In this way, the planet’s temperature is kept constant despite fluctuations in the stars temperature.
When it was first introduced in 1983, Daisyworld was roundly criticized by many scientists as being too simplistic. The model did, however, address two important criticisms of Gaia theory. First, it showed that a biologically regulated planet didn’t have to be teleological, that a self-regulating planet could arise without any need for a guiding conscious. Secondly, it showed that Gaia theory and Darwinian evolution were compatible, that indeed, it was natural selection that made Gaia theory work.
Nowadays, there are many different forms of Gaia theory, from “weak” to “strong.” Weak Gaia maintains only that life is important in shaping the Earth. This form of Gaia theory is generally accepted by many scientists today. In contrast, strong Gaia—the form that Lovelock endorses— says that life doesn’t just merely influence the physical processes of the planet, but actually controls them.
Lovelock, now 86-years old, is still working to develop Gaia theory. He believes that if Gaia theory were to become widely accepted, it would fundamentally change how humans view themselves and their environment:
“If we are ‘all creatures great and small,’ from bacteria to whales, part of Gaia then we are all of us potentially important to her well being…No longer can we merely regret the passing of one of the great whales, or the blue butterfly, nor even the smallpox virus. When we eliminate one of these from Earth, we may have destroyed a part of ourselves, for we also are a part of Gaia.
“There are many possibilities for comfort as there are for dismay in contemplating the consequences of our membership in this great commonwealth of living things. It may be that one role we play is as the senses and nervous system for Gaia. Through our eyes she has for the first time seen her very fair face and in our minds become aware of herself. We do indeed belong here. The earth is more than just a home, it’s a living system and we are part of it.”