The history of bark canoes includes the advent of necessary tools and the skills to build such complex craft. Early people in the Americas made some sophisticated tools including things like Clovis and Folsom points, so they were skilled. Even so, while bark canoes could predate the 2500 ya mark, it is unclear how the human occupation of what it now Milo, Maine provides any evidence of the age of bark canoe development. The core of the argument above seems to be that people got to the Milo area before 2500 years ago and bark canoes were the only way to get there, so bark canoes must have been around more than 2500 years ago. But he notion that "remote upland places like Milo"may not have been easily accessible with dugouts doesn't mean that bark canoes, other boats, or even water travel at all had anything to do with the area's prehistoric settlement. Milo sits only 100m above sea level, and people could have accessed that area on foot, through the use of animals, etc.
There are plenty of prehistoric human-occupied places with far more difficult access and places occupied much longer ago. In the Andes, more than 100 prehistoric human occupation sites are known above 5000m, with some elevations approaching even 7000m. The Nwya Devu site in central Tibet sits at 4600m, and it was occupied some 30,000-40,000 years ago. The extensive Andean culture grew to interact over great distances using an extensive network of roads despite much of the region being very high, very dry, and very cold, just like on the Tibetan plateau. The Andes and the Tibetan plateau, as examples, surely were far less accessible than what is now central Maine, which during its human prehistory was much wetter and warmer, and was far lower in altitude. If the concern is that water may have prevented access without boats of some kind, this document:
www.maine.gov
indicates that between 8000 and 5000 years ago, what is now Maine was drier, lake levels were lower, and river flows were probably considerably less, so people may have had had even more access then. Dating bark canoe technology is very interesting, but why assume canoes were the limiting factor for human access to the area during its prehistory?
