According to the hypothesis, complex extraterrestrial life is an improbable phenomenon and likely to be rare  . The term "Rare Earth" originates from Rare Earth: Why Complex Life Is Uncommon in the Universe (2000), a book by Peter Ward, a geologist and paleontologist, and Donald E. Brownlee, an astronomer and astrobiologist, both faculty members at the University of Washington. In the 1970s and 1980s, Carl Sagan and Frank Drake, among others, argued that Earth is a typical rocky planet in a typical planetary system, located in a non-exceptional region of a common barred-spiral galaxy. From the principle of mediocrity (extended from the Copernican principle), they argued that we are typical, and  the universe teems with complex life. However, Ward and Brownlee argue that planets, planetary systems, and galactic regions that are as friendly to complex life as the Earth, the Solar System, and our  galactic region are  rare.
According to the hypothesis, complex extraterrestrial life is an improbable phenomenon and likely to be rare throughout the universe as a whole . The term "Rare Earth" originates from Rare Earth: Why Complex Life Is Uncommon in the Universe (2000), a book by Peter Ward, a geologist and paleontologist, and Donald E. Brownlee, an astronomer and astrobiologist, both faculty members at the University of Washington. In the 1970s and 1980s, Carl Sagan and Frank Drake, among others, argued that Earth is a typical rocky planet in a typical planetary system, located in a non-exceptional region of a common barred-spiral galaxy. From the principle of mediocrity (extended from the Copernican principle), they argued that the evolution of life on Earth, including human beings, was also typical, and therefore that the universe teems with complex life. However, Ward and Brownlee argue that planets, planetary systems, and galactic regions that are as accommodating for complex life as the Earth, the Solar System, and our own galactic region are not typical at all, but actually exceedingly rare.
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throughout the universe as a whole
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we are
the evolution of life on Earth, including human beings, was also
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therefore that
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friendly to
accommodating for
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own
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not typical at all, but actually exceedingly