When and how humans first settled in the Americas is one of the historical mysteries that has fueled debate for centuries.
In the 20th century, archaeologists believed they reached the interior of North America about 14,000 years ago. However, thanks to recent research published in the scientific journal “Science” in September 2021, this view has finally undergone a significant change, which supports the theory that humans were present in the Americas about 23,000 years ago.
Humans have been in the Americas since the end of the Ice Age
Initially, it was thought that humans first reached the American continent via an ice-free passage that formed between two large ice sheets in the region now known as Canada and North America. Matthew Robert Bennett and Sally Christine Reynolds, two researchers, explained this through The Conversation.
This road was formed by melting at the end of the last ice age and is believed to have allowed humans to travel from Alaska to the interior of North America. This is the logical explanation for how humans first came to the Americas.
However, over time, this theory began to be debated and the early date began to decline. In recent decades, the date of human presence in the Americas has been pushed back from 14,000 years ago to 16,000 years ago.
While this date is still consistent with the idea that humans arrived in the Americas after the end of the last ice age, doubts about the chronology are growing.
Humans have lived in the Americas for over 23,000 years
In 2021, a study published in the journal “Science” shocked the scientific community. The research presents evidence that humans were present in the Americas about 23,000 years ago, the height of the last Ice Age.
The discovery comes from fossilized footprints found in New Mexico, specifically in the White Sands region. The footprints are thought to come from a group of humans walking through an ancient lake near White Sands.
This discovery not only adds 7,000 years to human history in the Americas, but also changes the paradigm of American prehistory. Thus, this leaves open the possibility that humans may have reached the Americas before the end of the last Ice Age, or perhaps they arrived there at an earlier stage of the melting.
Discussion on results
The results of this study have certainly received a lot of criticism. However, the research team has conducted a series of experiments to confirm this. Radiocarbon dating is a technique based on the radioactive decay of the carbon-14 isotope in organic matter.
Although some critics have suggested that the radiocarbon dating may have been affected by the effects of “hard water”, the research team carefully examined this.
They radiocarbon dated ditch grass seeds found in sedimentary layers above and below the fossil footprints. Ditch grass is an aquatic plant, and the seeds of this plant have been depleted by water for a long time, making them appear older than their actual age.
However, this study shows that there is no effect of old water on radiocarbon dating results.
In addition to radiocarbon dating, the research team used another dating method called optically stimulated luminescence (OSL). The OSL method relies on the accumulation of energy in buried quartz grains over time. By measuring this energy, they were able to determine the age of the quartz grains and compare them with radiocarbon dating results to verify the date of discovery.
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