ALUMINUM | In a 31,000-square-foot
laboratory punctuated by enormous machines in
bright blues and oranges, Purdue scientists have
solved a mystery more than 3 million years in
Using state-of-the-art equipment in the Purdue
Rare Isotope Measurement (PRIME) Lab, they’ve
dated the Little Foot skeleton at 3.67 million years
old. That beats Lucy by half a million years.
Little Foot, from South Africa’s Sterkfontein
cave, has been studied for two decades. Darryl
Granger had previously used his radioisotopic
dating technique to measure aluminum- 26 and
beryllium- 10 in rock samples surrounding the
fossil, suggesting that Little Foot came before
Lucy. His results were questioned, however, since
cave formations near the skeleton only dated back
2. 2 million years.
But in 2014, the lab’s new
gas-filled magnet detector
increased the accuracy of his
aluminum- 26 measurements
and verified his earlier results.
“I knew right away this would be big
news,” says Granger, an earth, atmospheric and
planetary sciences professor who collaborated
with researchers around the world. “The new
stratigraphy supports our results for the age
of the skeleton, while also explaining the
considerably younger age for cave formations
dated by other methods.”
Marc Caffee, physics professor and PRIME lab
director, is impressed by the increased precision.
“We hope to measure radionuclides that we can’t
measure at all now,” he says. | K.M.
Modern-Day Readings Confirm Little Foot’s Age
DARRYL GRANGER | MARC CAFFEE