"Before the ocean rose to near its current level some six to eight thousand years ago, the Cape and Islands were just relatively nondescript ridges in an immense plain that stretched all the way to . The first pioneer plants were probably various cold-weather berries, along with , , and . and wandered in, followed by the sturdy humans who made a living hunting them. Many of the smaller species of wildlife that now inhabit the various islands arrived by land as well, only to be isolated when the water rose, and ate away at both and . Nantucket and Martha's Vineyard each has its own particular subspecies of short-tailed shrew, both of which differ from the short-tailed shrew of the mainland."