Friedrich Wilhelm Heinrich Alexander Freiherr von Humboldt (help·info) (September 14, 1769 – May 6, 1859) was a German naturalist and explorer, and the younger brother of the Prussian minister, philosopher, and linguist, Wilhelm von Humboldt (1767-1835). Humboldt's quantitative work on botanical geography was foundational to the field of biogeography.
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