Monday, January 19, 2015

Wonderwerk Cave: Oldest Humanoid Campfire

Humans and our apelike ancestors have lived in Wonderwerk Cave for 2 million years.
The cave contains the earliest solid evidence that our ancient human forebears (probably Homo erectus) were using fire.

Researchers were trying trying to determine the age of sediments in a section of the cave where other researchers had found primitive stone tools. In the process, the team unearthed what appeared to be the remains of campfires from a million years ago — 200,000 years older than any other firm evidence of human-controlled fire..... when they saw carbonized leg and twig fragments. Then they discovered burned bits of animal bones as well. The bones’ sharp edges, and the excellent preservation of the plant ash, indicated that neither wind nor rain had ushered in the burnt material. The burning clearly had occurred inside the cave.

Then, when they ran an FTIR analysis on one of the sediment slices, the sample’s infrared signature showed that the cave material had been heated to between 750 and 1,300 degrees Fahrenheit. That was just right for
a small fire made out of twigs and grasses.

This supported a theory of human origins called the “cooking hypothesis" which aimed to fill a gap in the story of how early hominins like Australopithecus — essentially, apes that walked upright — evolved into modern Homo sapiens. Evolutionary science shows that our distant progenitors (Proconsul) became bipedal 6 million to 7 million years ago. Archaeologists believe early hominins evolved bigger brains as they walked, took up hunting and developed more complex social structures. That process led to the emergence of Homo habilis, the first creature generally regarded as human, 2.3 million years ago. Yet H. habilis’ brain was only moderately larger than Australopithecus’, and its body retained many apelike features. No one knows why, just 500,000 years later (1.8 mya), a radically more advanced species — Homo erectus — emerged. Its brain was up to twice the size of its predecessor’s, its teeth were much smaller, and its body was quite similar to ours.
Wrangham credits the transformation to the harnessing of fire. Cooking food, he argues, allowed for easier chewing and digestion, making extra calories available to fuel energy-hungry brains. Firelight could ward off nighttime predators, allowing hominins to sleep on the ground, or in caves, instead of in trees. No longer needing huge choppers, heavy-duty guts or a branch swinger’s arms and shoulders, they could instead grow mega-craniums. The altered anatomy of H. erectus, Wrangham wrote, indicates that these beings, like us, were “creatures of flame.”
There was one major problem with this hypothesis, however: Proving it would require evidence of controlled fire from at least 1.8 million years ago, when the first H. erectus appeared......
Then came Wonderwerk. The ash-filled sediment that Goldberg and Berna found came from a spot approximately 100 feet from the entrance to the tunnel-like cave, too far to have been swept in by the elements. The team also found circular chips of fractured stone known as pot-lid flakes — telltale signs of fire — in the same area. These clues turned up throughout the million-year-old layer of sediment, indicating that fires had burned repeatedly at the site.....

At Wonderwerk, team members plan to probe deeper, analyzing sediments up to 1.8 million years old, for evidence of fire. And they are using their cutting-edge detection methods at other early H. erectus sites as well.

Approximate timeline:
Proconsul 6+ MYA->
Australopithecus 3.9 MYA->
Homo habilis(fire&tool creator) 2.3 MYA ->
Homo erectus 1.8 MYA ->
Homo sapiens first beginning 400,000 years ago to present

Note: "Homo sapiens has always used fire as a tool / our species has always been augmented by the invention of artificially made fire and tools."