NEW YORK (AP) - When did our ancestors first use fire? That's been a
long-running debate, and now a new study concludes the earliest firm
evidence comes from about 1 million years ago in a South African cave.
The ash and burnt bone samples found there suggest fires frequently
burned in that spot, researchers said Monday.
Over the years, some experts have cited evidence of fire from as long as
1.5 million years ago, and some have argued it was used even earlier, a
key step toward evolution of a larger brain.
...The ancestors probably brought burning material from natural blazes
into the cave to establish the fires, said Michael Chazan of the
University of Toronto, a study author. Stone tools at the site suggest
the ancestors were Homo erectus, a species known from as early as about
2 million years ago.
The scientists didn't find signs of fire preparation, like a hearth or a
deep pit. But Berna said it's unlikely the fires were simply natural
blazes, such as from lightning strikes.
That's because the evidence shows repeated fires burned deep inside the
cave, he said. The cave entrance is almost 100 feet away, and because of
changes in the cave over the past 1 million years, the entrance was
apparently even farther away when the fires burned, he said.
...Berna and colleagues describe animal bones that show discoloring and
a chemical signature of being heated. They also report microscopic bits
of ash in excavated dirt from the cave, indicating burning of light
material like leaves, grasses and twigs. And they found evidence of
heating in samples of fractured stone.
Several lines of evidence suggest the material was heated within the
cave rather than blown or washed in from outside.
It's not clear what the fires were used for. While the burnt bones
suggest cooking, the ancestors might have eaten the meat raw and tossed
the bones into the fire, Berna noted. Other possible uses might be
warmth, light and protection from wild animals, he said.
Berna said researchers will return to the Wonderwerk cave this summer
and pursue hints that fires were used there even earlier than their
paper suggests.
Online:
Journal website: http://www.pnas.org
Wonderwerk Cave information: http://bit.ly/H4sDS4
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