Elisabeth S. Vrba (May 27, 1942 – February 5, 2025) was an American paleontologist at Yale University who developed the turnover-pulse hypothesis which suggests that major changes to the climate or ecosystem often result in a period of rapid extinction and high turnover of new species (a "pulse") across multiple different lineages. Together with Stephen J. Gould, they developed the term exaptation to describe a trait that performs a function but originally evolved for a completely different purpose.
Background
Vrba was born in Hamburg, Germany. In 1944, following the death of her father, she moved with her family to a sheep farm in Namibia. She earned her Ph.D. in Zoology and Palaeontology at the University of Cape Town, in 1974. Vrba studied zoology and mathematical statistics at the University of Cape Town to earn her undergraduate degree. She remained there for doctoral study in zoology and paleontology to earn her Ph.D. After receiving her doctorate, Vrba conducted her early research on African fossil records over the last several million years, tracking the sequence of fossils from analyzing the geological strata and analyzing the morphology of the fossils. She was the chief assistant to Charles Kimberlin Brain during his directorship of the Transvaal Museum.
Vrba was appointed a professor at the Department of Geology & Geophysics, Yale University, in 1986 and retired in 2014. She is well known for developing the turnover-pulse hypothesis, as well as coining the word exaptation with colleague Stephen Jay Gould. Her specific interest was in the Family Bovidae (antelopes, etc.), but her students studied a wide range of species.
Innovations
Vrba and colleague Stephen Jay Gould are renowned for having proposed the term exaptation. Vrba and Gould's research suggested that the historical origin of a genetic or morphological trait is not always reflective of its contemporary function — genesis and current function should not be conflated. Genetic or morphological adaptations may take on new functions and may serve a species a different purpose further on in evolution. Gould died in 2002, but their coined term has been widely referenced in recent years in popular science writing. Vrba and Gould's idea of exaptation has also been criticized in recent years by scholars who assert that genetic traits are pressured by multiple factors, making it challenging to determine when adaptation or exaptation is at play.
↑Vrba, Elisabeth (1993). "Turnover-Pulses, the Red Queen, and related topics". American Journal of Science. 293: 418–452. doi:10.2475/ajs.293.A.418.
↑Vrba, Elisabeth (1987). "Ecology in relation to speciation rates: Some case histories of Miocene-recent mammal clades". Evolutionary Ecology. 1: 283–300. doi:10.1007/BF02071554.
↑Vrba, Elisabeth (1992). "Mammals as a key to evolutionary theory". Journal of Mammalogy. 73: 1–28. doi:10.2307/1381862.
