Your articles on human dispersal in the late Pleistocene epoch (Nature 485, 23; 2012) overlook the significance of now-submerged archaeological sites on the continental shelf during this period (126,000–11,000 years ago). It is wrong to assume that these were completely destroyed by the sea and that the interpretation of human movements must rely on proxy data, such as DNA or evidence from islands.
More than 3,000 prehistoric sites on the seabed have been found and mapped, and in some cases excavated. They range in age from 500,000 to 5,000 years old, and at locations from the present-day shoreline out to a depth of 130 metres. These sites were extensive, often located on key travel routes and more attractive than arid hinterlands to human settlers.
Marine archaeologists have recovered in-context stone artefacts, animal remains and human fossils from such sites. Some materials, including food remains, organics, bone, DNA and plants, are better preserved underwater than on land.
Questions of early human dispersal will not be resolved until continental shelves are fully investigated — spurred by advances in modern oceanographic technology (see http://splashcos.org).