Review by Elizabeth Quill
In 1964, Paul Colinvaux began his life’s work—trying to understand the ice-age climate of the Amazon through mud cores and the pollen found within. Having sharpened his drill in the Arctic, the ecologist looked south to “terra incognita.” When he began his effort, no ice-age deposit or site in the Amazon had been identified.
Then in 1969, ornithologist Jurgen Haffer proposed a hypothesis to explain the Amazon’s vast biodiversity. During the last ice age (which peaked about 21,000 years ago), he suggested, most of the forest became arid grassland. In pockets of surviving greenery, speciation occurred. The new species repopulated the forest when it returned, contributing to its diversity.
Despite a lack of evidence, the refuge hypothesis gained appeal. Colinvaux’s