No. 40: Jul-Aug 1985
Marine stratigraphy, radioactive dating, and paleontology all point to the relatively recent emergence and biological colonization of the Galapagos. These islands are no older than 3-4 million years. The unique terrestrial life forms had to develop in less time than this.
(Hickman, Carole S., and Lipps, Jere H.; "Geologic Youth of Galapagos Confirmed by Marine Stratigraphy and Paleontology," Science, 227:1578, 1985.)
Comments. Several remarks seem appropriate here:
(1) The varied fauna and flora of the Galapagos did not evolve independently; viz., the bills of the Darwin finches are tailored to specific food sources (plants). Many species changed rapidly and in concert. (2) A recent Science article (228: 1187, 1985) notes that inbred mice often evolve different morphological characteristics very quickly. This observation probably applies to the initial Galapagos populations, which must have been small and inbred. (3) Harking back to the item on the Guadeloupe skeleton, the Galapagos display similar strata of limestone, beach rock, etc. Until now, the limestones had been dated from the Miocene to the Pleistocene, but according to Hickman and Lipps they must be much younger than Miocene. The Guadeloupe dates may also be in error. Caveat emptor.