<human>:  When did James Lovelock first propose the Gaia hypothesis?
<bot>: The Gaia hypothesis was first proposed in the 1970s. James Lovelock, a British scientist, proposed that the Earth itself could be viewed as a living organism, and that its atmosphere, oceans, and landforms were part of a single, self-regulating system. The Gaia hypothesis has been widely criticized, however, and many scientists have rejected it.