Humans may have left and been exploring other continents including Europe far earlier than we knew.
"This discovery challenges the established narrative of early human evolution head-on and is likely to generate a lot of debate," said Professor Per Ahlberg, who was an author on the study.
The age of the carbon in the rock is different from that of the carbon in the air and makes carbon dating data for those organisms inaccurate under the assumptions normally used for carbon dating.
This restriction extends to animals that consume seafood in their diet.
Carbon-14 cannot be used to date biological artifacts of organisms that did not get their carbon dioxide from the air.
This rules out carbon dating for most aquatic organisms, because they often obtain at least some of their carbon from dissolved carbonate rock.
But the new discovery of a footprint that appears to have belonged to a human that trod down in Crete 5.7 million years ago challenges that story.
These isotopes have longer half-lives and so are found in greater abundance in older fossils.
Some of these other isotopes include: back to the last global catastrophe (i.e.
When scientists first began to compare carbon dating data to data from tree rings, they found carbon dating provided "too-young" estimates of artifact age.
Scientists now realize that production of carbon-14 has not been constant over the years, but has changed as the radiation from the sun has fluctuated.
All of that led them to conclude that the foot appeared to belong to our early human ancestors, who could have been walking around Europe at an early time than we ever knew.