A new study has revealed that humans existed 400,000 years before than previously believed. An international team of geoscientists and anthropologists dated the recently found Ledi-Geraru fossil mandible in the Afar region of Ethiopia to be between 2.8 and 2.75 million years old. The scientists also dated other fossils to between 2.84 and 2.58 million years ago, which helped reconstruct the environment in which the individual lived.
Lead author of the study, Erin N. DiMaggio, said, "The record of hominin evolution between 3 and 2.5 million years ago is poorly documented in surface outcrops, particularly in Afar, Ethiopia."
The recently discovered fossil, known by its catalog number LD 350-1, was dated using argon40 argon39 dating, a method that measures the different isotopes of argon and determines the age of the eruption that created the sample. DiMaggio said, "We were confident in the age of LD 350-1, as we used multiple dating methods including radiometric analysis of volcanic ash layers, and of which show that the hominin fossil was 2.8 to 2.75 million years old."
Other fossils found in this area were those of prehistoric antelope, water dependent grazers, prehistoric elephants, a type of hippopotamus and crocodiles and fish. These fossils fall are 2.84 to 2.54 million years old. These fossils suggest that the area was a more open habitat of mixed grasslands and shrub lands with a gallery forest-trees lining rivers or wetlands. The landscape could probably be similar to African locations like the Serengeti Plains or the Kalahari. Some researchers suggest that global climate change intensifying roughly 2.8 million years ago resulted in African climate variability and aridity and this spurred evolutionary changes in many mammals.
The results appear online in Science Express.