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Why the oldest human fossil ever discovered changes everything

In an archaeological dig in Ethiopia, scientists have discovered a jawbone complete with five intact teeth that belong to the earliest member of our genus that has ever been found.

Humans, with the genus Homo, were thought to have emerged between 2.3 to 2.4 million years ago. That’s all changed, with this fossil dated between 2.75 and 2.8 million years old.

The fossil was dated by examining volcanic ash in the layers around it, and looking at isotopes of argon to determine when it was created.

It’s a hugely significant finding, published in three studies this week.

Surprisingly little is known about the human Homo genus’ very early evolution, with in an important transitional interval between 2.5 and 3 million years ago having no known fossils – until now.

This fossil, known as LD 350-1, or Ledi, is a partial, left lower-jaw. It was found in 2013 by Arizona State graduate student Chalachew Seyoum – who himself hails from Ethiopia.

“Honestly, it was an exciting moment,” Seyoum said. “I had good experience in field surveying and knew where potential sediments are. I climbed up a little plateau and found this specimen right on the edge of the hill.”

For archaeologists, it’s a tremendously important find, and the lead research team – headed by Brian Villmoare from the University of Nevada Las Vegas and Arizona State’s William Kimbel – explained why in a news release:

“To have a glimpse of the very earliest phase of our lineage’s evolution is particularly exciting,” said Villmoare.

“The Ledi jaw helps narrow the evolutionary gap between Australopithecus and early Homo,” Kimbel added. “It’s an excellent case of a transitional fossil in a critical time period in human evolution.”

Other fossils found in this area include prehistoric elephants, antelope, hippos, crocodiles, and fish.

Image credit Kaye Reed

Mandible of LD 350-1 found by Chalachew Seyoum / credit Kaye Reed
Mandible of LD 350-1 found by Chalachew Seyoum / credit Kaye Reed
Site where the mandible was found
Site where the mandible was found
Map of the Ledi site in Ethiopia
Map of the Ledi site in Ethiopia

About the author

Tristan has a passion for tech, digital life, sport, and being told he looks better in person.

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