, Volume 5, Issue 4, pp 519-520


This is an excerpt from the content

Geography has played an important role in the minds of biologists since the very beginnings of scientific analysis of the evolutionary process. Early biologists and paleontologists knew that particular forms of life—especially among groups of complex organisms, such as terrestrial vertebrates—tend to be restricted to certain areas: life is not distributed homogeneously around the globe. When Darwin was a young naturalist on the HMS Beagle, he zeroed in on the native endemic mammals and birds of South America. Darwin was looking for patterns of “births” and “deaths” of species—so focusing on groups of species restricted to a single area automatically meant that species must have originated there—rather than migrating in from someplace else. He hit pay dirt when he discovered fossil remains of an extinct species of rodent he thought must have been ancestral to the living mara—which he called the “Patagonian cavy.” Caviomorph rodents are distinctively South American.

Darwin then saw that “