Earlier Migration

Theories surrounding how the Americas grew to become inhabited vary somewhat and have been challenged within relatively small margins of thousands of years. However, a new theory is disputing the preconception that our hominin ancestors arrived roughly 15,000 years ago, potentially drawing that date back 100,000 years or more.

A group of researchers in California found remains of animal bones appearing to have been crushed by stones at the hands of early hominids, as opposed to homo sapiens. The researchers say that their evidence is supported in the way the bones were crushed matching similar behavior and techniques by hominin tools of that era.

The bones were found during construction on a road in San Diego in 1992, whereafter an excavation, led by paleontologist Tom Deméré uncovered teeth and tusks of a mastodon that had been smashed, seemingly by a hammer and anvil stone.

Traditional theories hold that between 15-20,000 years ago, homo sapiens hunting large mammals crossed over a land bridge between what is modern day Siberia and Alaska over the Bering Strait. The team of researchers that discovered the bones was unable to extract any carbon for dating, but was able to use a method of radioactive dating that appears to hold up. But Deméré’s colleagues have had mixed reactions.

In an interview with the Washington Post, one fellow paleoanthropologist, recognized that their site, “contains less archaeological evidence than scientists would like before making a claim of this magnitude. But as someone who has spent her whole career looking at scratch marks and breakage patterns on bones, the evidence looks to her like it could be human modification.”

Source: A. Rountrey, C. Abraczinskas and D. Fisher/Univ. Michigan

Ghost Populations

Although this traditional theory has been widely held, often new evidence will arise that adds layers and challenges it. One such example is in the “ghost populations” of esoteric tribes deep in the Brazilian Amazon whose members’ DNA can be traced back to Australasian ancestors. It is still unclear as to how these ancestral groups migrated and whether or not they assimilated with their Siberian counterparts, but the majority of Native American DNA can be traced to a single group, making this discovery more intriguing.

There are two tribes in particular from the Amazon, the Suruí and the Karitiana, whose lineage can be traced back to Papua New Guinea and Australia. The theory still holds that these ancestors crossed the same land bridge over the Bering Strait, however it is likely that they were pushed out in North America and much of South America by the more prominent migrants. This ancestral group, dubbed, “Population Y,” no longer exists in Asia.

Archeological Debate

While the theory of the ghost population has been accepted, unsurprisingly, stalwarts of archeology are rejecting the new hypothesis of a significantly earlier migration. But Deméré insists there is a connection to similar patterns in which bones were struck at a particular angle that have been seen in instances of that era. He also claims to know of other sites that he believes may contain more evidence supporting his theory. Deméré and his team urge his colleagues to remain open to his hypothesis and not immediately dismiss it.

A skeptical colleague of the team, who says he has seen misinterpretations in similar cases in the past, told the Washington Post,  “It is one thing to show that broken bones and modified rocks could have been produced by people. It is quite another to show that people, and people alone, could have produced those modifications.”

The diaspora of  humans from the African continent is typically thought to have occurred less than 100,000 years ago, however human teeth found in China dating back 120,000 years could be evidence of an earlier migration. If the theory proves to be true, these ancestors could be either Neanderthal, Homo erectus or Denisovans, the latter being an extinct species that was found to have inhabited Siberia.