When did humans rise to become the dominant species on the planet? It might not be as long ago as you might think. Scientists now believe that humans didn't truly rise to become the dominant species on the planet with the ability to drastically impact the planet until 1610 when Galileo was studying the stars and King James sat upon the thrown of England.
So why 1610 and not sometime earlier such as the time of the Roman Empire or maybe even earlier when the Egyptians were crafting the Pyramids? Scientists argue that 1610 is when the irreversible transfer of both crops and species between the new and old worlds started to truly be felt.
Simon Lewis, an ecologist at University College London and author of the paper, said: "In a hundred thousand years, scientists will look at the environmental record and know something remarkable happened in the second half of the second millennium. They will be in no doubt that these global changes to Earth were caused by their own species."
When Europeans started arriving in the Americas, he added, a cascade of events was triggered that was "as Earth-changing as a meteorite strike."
While the concept of "Anthropocene" is already widely used among environmentalists and writers, scientists remain divided on whether a new time period designation is really necessary.
Critics argue that the desire to redraw geological boundaries are motivated by those wishing to highlight the extent of human destruction while others believe it is actually set 1,000 years too soon.
The International Commission on Stratigraphy is actively considering the question and is working with a group to further study the issue with a report due next year.
"Global long-term changes to Earth's system ... are required to have one marker that can be precisely dated that is captured in some ancient geological material," said Lewis.
Lewis and his UCL co-author, Mark Maslin, considered many defining human moments as possible candidates but finally came to the conclusion that the joining of the continents and nuclear testing were the best fit.
The year 1610 marks a dip in the global carbon dioxide levels as there was much less farming in the Americas due to the approximately 50 million deaths of the indigenous peoples due to the introduction of small pox. A second marker for this time period is the appearance of pollen maize, a Latin American species, in the European marine record.
The authors conclude that 1610 has a stronger claim and that nuclear testing has not been an Earth-changing event. "I tend to go with 1610 because ... the evolutionary consequences of that are pushing Earth onto a new evolutionary trajectory," said Lewis.
The arrival of the Anthropocene would mark the end of the Holocene, the epoch in which we currently live. The Holocene itself wasn't defined in 2008 and was set based on the Greenland ice cores that ended the last ice age approximately 11,700 years ago.
Some believe that since epochs typically last tens of millions of years, the Holocene should be scrapped or at least downgraded. "The Holocene is supposed to last tens of millions of years and it's several orders of magnitude to short," said Lewis. "I think we'd have to call that a stage rather than an epoch."
