The Gaia theory was first proposed by James Lovelock, a British research scientist. The theory holds that the Planet Earth is self-regulating, much like the human body.

Question

To understand this idea, it helps to think of how the human immune system helps us to fight off illness and maintain a constant body temperature (roughly 98.6 degrees Fahrenheit). The Gaia theory suggests that the Earth has a similar mechanism—like the immune system—which helps it maintain planetary stability and health.
Lovelock formulated the Gaia theory in the 1960s while he was working for NASA. At the time, he was trying to explain several conditions that puzzled him. Among these conditions were:
the Sun provides more energy than it used to, and yet global surface temperatures have not increased in the same proportion.
the chemical composition of the atmosphere around us, which is composed of 79% nitrogen, 20.7% oxygen, and 0.03% carbon dioxide, has changed very little over time.
the levels of salt in the ocean have not changed.
To Lovelock, the above facts demonstrated that our planet Earth is extremely stable. He decided that the Earth must be composed of complex systems that interact with one another in order to support life. Some people interpret this to mean that the Earth is like a single living organism. Just as our bodies are composed of millions of tiny cells, so too the Earth is composed of many plants, animals, and other elements that are like its "cells." In this view, all of us—humans, plants, and animals—are working together to support one another, whether we know it or not.
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Based on the central idea, which would be the best title for this passage?
A.
Gaia Theory Suggests Earth Has Own Immune System
B.
NASA Scientist Puzzled by Earth's Strange Atmosphere
C.
Gaia Theory No Longer Meaningful in Search for New Life
D.
Earth Maintains Stability with Help from British Scientist

Answer 1

A. Gaia Theory Suggests Earth Has Own Immune System