Ancient Ape Booted from Human Family Tree

Researchers have dated the ape-man skeleton, known as 'Little Foot', found in 1997 in Sterkfontein cave in South Africa to be precisely 2.2 million years old.

The skeleton was previously was known to be between two million and four million years old, but its exact date was unknown.

These new findings reveal that the creature--part of the Australophithecus africanus family--may not be the immediate ancestor of human beings as some experts originally thought.  This is because the team found that 'Little Foot' lived after the arrival of the stone tool makers, Homo habilis, raising the possibility that this family was more of a side branch of the human evolutionary tree. 

"It was discovered cemented in layers of stalagmites and archaeologists are continuing to extract the skeleton from the hardened deposits," said Alfred Latham a researcher from the University of Liverpool. "We believe that 'Little Foot' either fell down a shaft or somehow got trapped in the cave and died there.  The remains were preserved in the stalagmite layers and it is these layers that have helped our team to date the skeleton."

In order to ascertain the age of the skeleton, researchers used a technique called uranium-lead dating.  Stalagmite layers contain traces of radioactive uranium, which eventually decays to form lead.  The team measured the amount of uranium and lead in the stalagmite layers to form an accurate date for their age and for that of the skeleton.

Uranium-lead analysis has proved to be more accurate than other dating techniques as it does not rely on animal remains or sediment traces surrounding the excavation site. Animal remains or sediment traces are often buried in many layers of hardened deposits making it difficult for archaeologists to pin point exactly where and when the specimens were in existence.

---LiveScience Staff

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Credit: the University of Liverpool