A study shows evidence vital to understanding human prehistory beneath the seas in places that were dry during the Last Glacial Maximum. This paper informs one of the 'hottest mysteries' in science: the debate over when the first Asians peopled North America.

Coastal areas during the Last Glacial Maximum likely would have attracted people, as coastal lands do today. Dobson said archeological exploration is needed to search for boats, ports and settlements -- evidence that could revolutionize conceptions of human migration and know-how at that time.

"How much technology was there?" he said. "Were there boats? No boats have ever been found that were that old, but we know people made it from Southeast Asia to Australia 65,000 years ago. So, anthropologists surmise they must have had boats. Even when sea level was at its lowest, the individual hops they had to make were long enough that it would seem likely they had boats. In the new article, we study the history of boats of all kinds based on research published in reputable scientific journals. Maritime travel goes surprisingly far back. So now, what kind of evidence can we find of ports? No one has ever claimed evidence of ports that far back. Of course, ports on coasts 400 feet lower than today would be hard to find, and precious little underwater archaeology has been conducted at that depth. We need to treat boats and ports as unknown and look for the evidence rather than proclaiming whether it did or did not happen."

The KU researcher said choke points should be of interest to geographers, ocean scientists, underwater archeologists, anthropologists and oceanographers because they provide "strategic insights on where to search for submerged evidence of human settlement."

"It's a matter of efficiency," Dobson said. "To understand maritime travel and associated settlements long ago, we can search whole oceans. Underwater searches are expensive, however, so little territory gets searched. Finds are rare because artifacts are few and far between. Choke points funnel travel into narrow corridors, and logically that concentrates the artifacts as well. If there is any evidence, that's where we most likely will find it."

Jerome E. Dobson, Giorgio Spada, Gaia Galassi. Global Choke Points May Link Sea Level and Human Settlement at the Last Glacial MaximumGeographical Review, 2020; 1 DOI: 10.1080/00167428.2020.1728195

Global choke points are preeminent nodes in geographic networks and geopolitical touchpoints subject to control by nations. They appear today as recurring theaters of conflict worldwide and also in archaeological investigations delving thousands of years back in time. How different were today’s global choke points at the Last Glacial Maximum (LGM) ~ 20,000 years ago? For the first time, we map nine of them to visualize their conditions at LGM. The global feature aquaterra—all lands inundated and exposed repeatedly during the Late Pleistocene ice ages—initially was mapped as first approximations of sea level. Here we refine its boundaries using Glacial Isostatic Adjustment (GIA) models to account for the Earth’s deformation and horizontal migrations of shorelines in response to glacial melting. We found three choke points sufficiently open to navigation, but six others presented substantially greater barriers than today. Implications include strategic insights on where to search for submerged evidence of human settlement.

Keywords: global choke pointshypsographyLast Glacial Maximumsea-level change