在行星科学和天体生物学中，地球殊异假说（英语：Rare Earth hypothesis）认为地球上多细胞生物的形成需要不同寻常的天体物理及地质事件和环境的结合。「地球殊异」（Rare Earth）这一词来自于一本由彼得·瓦尔德（Peter Ward ）和唐纳德·E·布朗尼（Donald E. Brownlee）所着的《地球殊异：为何复杂生命在宇宙中并不普遍？》（Rare Earth: Why Complex Life Is Uncommon in the Universe，**译名：“地球是孤独的：从天文物理学、太空生物学、行星科学探索生命诞生之谜”）一书。

In planetary astronomy and astrobiology, the Rare Earth Hypothesis argues that the origin of life and the evolution of biological complexity such as sexually reproducing, multicellular organisms on Earth (and, subsequently, human intelligence) required an improbable combination of astrophysical and geological events and circumstances. The hypothesis argues that complex extraterrestrial life is a very improbable phenomenon and likely to be extremely 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.