New Instrument Dates Old Skeleton;
‘Little Foot’ 3.67 Million Years Old
A skeleton named Little Foot is among the oldest hominid skeletons ever dated at
3.67 million years old, according to an advanced dating method.
Little Foot is a rare, nearly complete skeleton of Australopithecus first discovered
21 years ago in a cave at Sterkfontein in central South Africa. The new date places
Little Foot as an older relative of Lucy, a famous Australopithecus skeleton found
in Ethiopia and dated at 3. 2 million years old. Australopithecus is believed to be an
evolutionary ancestor to humans.
Stone tools found at a different level of the Sterkfontein cave also were dated at 2.18
million years old, making them among the oldest known stone tools in South Africa.
A team of scientists from Purdue University; the University of the Witwatersrand
in South Africa; the University of New Brunswick in Canada; and the University
of Toulouse in France performed the research, which was featured in the journal
Relatively small margin of error
Previously, there has been no consensus on the age of the Little Foot skeleton,
named for four small foot bones found in a box of animal fossils that led to the
skeleton’s discovery. The new dating relied on a radioisotopic technique pioneered
by Darryl Granger, a professor of earth, atmospheric and planetary sciences,
coupled with a powerful detector originally intended to analyze solar wind
samples from NASA’s Genesis mission.
The technique, called isochron burial dating, uses radioisotopes within several
rock samples surrounding a fossil to date when the rocks and the fossil were first buried underground. The result was a relatively
small margin of error of less than five percent. “It is expensive and a lot of work to take and run multiple samples, but I think this is
the future of burial dating because of the confidence one can have in the results,” says Granger, who, along with former postdoctoral
researcher Ryan Gibbon, led the team that performed the dating.
The team used Purdue’s PRIME Lab’s powerful accelerator mass spectrometer and a new gas-filled magnet detector to measure the
radioisotopes. Marc Caffee, a professor of physics and director of the PRIME Lab, assisted in the research. “Only a few detectors
of this kind exist in the world,” Caffee says. “One of the reasons I came to Purdue was to be a part of the revolutionary science that
can be done when such resources are applied to challenging problems. These results highlight what can be accomplished through a
collaboration that spans multiple disciplines. It couldn’t have happened without the unique skills and resources each person brought
to the table.”
New Class of Insecticides
Offers Safer, More
Targeted Mosquito Control
Catherine Hill and Val Watts have identified a new class of chemical insecticides
that could provide a safer, more selective
means of controlling mosquitoes that
transmit key infectious diseases such as
dengue, yellow fever and elephantiasis.
Known as dopamine receptor antagonists,
the chemicals beat out the neurotrans-mitter dopamine to lock into protein
receptors that span the mosquito cell
membrane. Disrupting the mechanics of
dopamine eventually leads to the insect’s
“These are sophisticated designer drugs.
They’re like personalized medicine for
mosquitoes, but in this case, the medicine
is lethal,” says Hill, professor of entomology and a Showalter Faculty Scholar.
The researchers are also taking steps to
minimize the risk that the insecticides
could bind with human dopamine receptors, says Watts, a professor of medicinal
chemistry and molecular pharmacology.
Catherine Hill, Val Watts
Darryl Granger, Marc Caffee