For years, anthropologists and archaeologists have puzzled over the origins of two famous aboriginal groups in the American Southwest: the Navajo and Apache people. The traditional languages spoken by the Navajo and the Apache differ strikingly from those of their neighbors, so much so that if you look at a linguistic map their homelands stand out like islands in a great sea.
But their languages are very closely related to the mother tongues of aboriginal people living in the subarctic in northwestern Canada and Alaska: indeed they belong to the same Athapaskan family. Moreover, linguists have long suggested that the ancestors of the Navajo and Apache people splintered off from their subarctic cousins roughly 1200 years ago. This begs a fascinating question. What might have prompted the ancestral Navajo and Apache to abandon their homeland in the northern forests and journey thousands of miles south to a very unfamiliar desert?
Some years ago, University of Alaska archaeologist William Workman proposed a possible answer. He suggested that the eruption of the White River volcano in southern Alaska around 1200 years ago could well have driven out both game and human hunters. Ash from the volcano blanketed a region of some 250,000 square kilometers: in some parts it reached 1.5 meters in thickness. All this, observed Workman, could well have forced the region’s Athapaskan speakers to search for a new homeland in the south.
Yesterday, a team led by Simon Fraser University researcher Tyler Kuhn shed new light on the dire nature of this eruption. In a new online paper in Molecular Ecology, Kuhn and his colleagues compared ancient DNA from caribou bones from the Yukon that dated before and after A. D. 1000. As the team discovered, the caribou living there before the White River eruption were genetically different from the caribou that resided there after.
In other words, a big change occurred in the local caribou population around the time of the White River eruption. The old herds vanished, and later new caribou herds moved in–quite likely as the land greened and grasses, sedges, willows and the like took hold once again.
All this strongly suggests that Athapaskan hunters in the area would have struggled to survive after the eruption. And indeed, archaeological evidence from the Yukon points to a major human transition as well. Before the eruption, the local hunters relied on throwing darts as their main weapon. After the ash fell, however, the inhabitants favored bow and arrows.
We are still a long way from definitive answers, but I’d say that it is looking more and more as if immense volcanic ash clouds, sunless days and a terrible famine changed the course of North American prehistory, pushing ancestors of the Navajo and the Apache peoples far to the south.
Heather Pringle 