Climate and New World periosteal reaction patterns: implications for migration routes into the western hemisphere

The presence of the diseases yaws and bejel are indicated by periosteal reaction patterns. The distributions of these two diseases in ancient North American human populations show evidence of climatic influence. Those ancient populations lacking either yaws or bejel (the null periosteal reaction pattern) can be found in the coldest parts of the Cold Winter Regions. Those populations with yaws (the poly-ostotic periosteal reaction) can be found in the milder portions of the Cold Winter Regions. The populations with bejel (the pauci-ostotic periosteal reaction) are found either outside of or marginal to Cold Winter Regions. The Bering Strait area is considered to be the gateway to the ancient New World. The cold climates present in this area should have influenced the routes available for the diseases to spread from population to population or by migration of infected populations into the Western Hemisphere. It is suggested that the coastal route with its milder maritime climate was the route taken by yaws when it entered the New World. The presence of bejel in ancient North America presents a conundrum. The climate would have blocked the spread of the disease from Siberia to Alaska in either Late Glacial or Holocene times. This suggests that our present view of migration routes is incomplete.