Posts Tagged ‘PNAS’

10. About the dating of the first use of fire.

How dare I assume that this taming of fire occurred some 2 million years ago? Most paleos don’t go farther back than the 790,000 years old Gesher Benot Ya’aqov site in Israel, where charred wood and seeds were recovered[1]. Most paleos only accept evidence of fire use when there are hearth stones used; but even today San people don’t use hearth stones when the cook a tuber en route. They dig up a tuber, gather some dry material and branches, sit down, make fire with turning around the point of a digging stick between the hand palms onto a dry piece of wood. When the tinder glows, they blow it in flame et voila!: fire. Some brave paleos accept the evidence from Swartkrans and Chesowanja dating 1.5 million years ago, but that is the limit.

For me as a humanosopher, there are three kinds of evidence of an earlier use. First: there is no other way our ancestor-australopiths could have evolved smaller teeth and more gracile chewing apparatus (mouth) than through more soft and digestible food. Second: no other way to become larger beings and with larger brainpans, than through some kind of radically improved food supply. As experimentally proven by Richard Wrangham[2], a raw (not cooked, not grilled, not roasted) chimpanzee diet would be simply inadequate to sustain larger-brained beings of human size. Three: palaeontologists such as Ralph Rowlett and Randy Bellomo studied the differences in the soil beneath a natural fire and a campfire. The soil under campfires reaches much higher temperatures and a campfire leaves behind a bowl-shaped layer of highly oxidized and magnetized soil. At Koobi Fora in the African Rift Valley, Jack Harris of Rutgers University in New Jersey found such evidence of campfires dating 1.6 million years ago. Fire control must have started a long time before that moment.

‘2 million years ago’ is of course not an exact date; it is just an educated guess.

Perhaps controlled fire existed even earlier than these 2 million years ago. The first ‘professional’ stone tools found at Kada Gona are 2.6 million years old. They attest to a new niche for protein: meat.

For the start of meat consumption, we have to look back to about 6 million years ago: to the hides that could be found all over the Miocene savannah. In the following millions of years the hooligans of the savannah, ever more audacious with their stones, learned to chase away feeding predators from their prey. That was the moment when the males began to contribute to the diet: carrion became an increasingly important part of nutrition.

About 2,5 million years ago, the earth climate became even more cool and dry: the onset of the Ice Ages. Woodland savannah began to turn into desert savannah. The carrion competition grew more fierce. The best sources of carrion, the pachyderms (elephants, rhinos, hippos) had skins that were too thick for lions and hyenas and vultures to penetrate. Those predators had to wait until, after two or three days, the skin cracked open by decomposition gasses. However, with their knife-sharp stone tools the ancestor-australopiths could start processing the dead animal immediately!

The evidence of the stone tools of Kada Gona (2,6 million years ago) is recently transcended by the publication of the Dikika Research Project: evidence of stone tool use and meat-eating dating back 3,4 million years![3] And who made and handled this early stone tools? In June 2010, the discovery of Kadanuumuu, a 3.6 million years old australopith, was published. Its skeleton was found in Afar, where also the famous Lucy-skeleton was found. But Kadanuumuu was nearly a half million years older, much taller and had a more humanlike shoulder blade. So in my view, these people were the butchers of the Dikika antelope from 3,4 million years ago.

The image on the right is a artist reconstruction of the Dikika Child fossil

Meat was a new protein niche for our hooligan ancestors. It incited them to improve their stone ‘knives’. For millions of years, the standard way to make a ‘knife’ or scraper had been to smash a stone against another stone or rock, and then pick out the best ‘knife’. In the new circumstances, this was no longer sufficient. I think knapping the ‘knife’ from a core stone with a hammer stone was too risky for long, bent ape fingers (they still needed those ape fingers for climbing quickly into trees for sleeping and safety). But in order to improve the stone ‘knives’ they needed some knapping technique; and in order to develop a knapping technique they would need shorter, “handier” fingers.

Evolution had to find a balance between the need for long, bent fingers for climbing and making nests in trees on one side, and the need for shorter, handier fingers for knapping better knives on the other. It was the use of the fire that altered this balance. Since the fire provided protection from predators, this made it possible to stay on the ground instead of climbing in a treetop to build nests. Because our australopith ancestors no longer needed to climb trees at night, they no longer needed long “ape” fingers. This allowed the development of shorter, handier fingers suitable for better knife production.

[1] in a recent PNAS article (March 2011) the paleos Roebroeks and Villa suggest that the real control of fire is not older than 400.000 years; we have to take in consideration that their research only concerns European archaeological sites, and that they emphasize that earlier use of fire was possible in an opportunistic way: using smoldering wood from a natural fire, keeping it smoldering in a gourd or something
[2] Cooking Up Bigger Brains (2008); Wrangham himself did a research experiment by trying to live on a chimpanzee diet of fruit and raw meat: he found it not feasible for humans!
3] in a PNAS-article 17 Oct.’10 Dominguez-Rodrigo et al. charged this claim and proposed the marks as inflicted by animals trampling on the bones. However, they didn’t look at the original specimens but based their arguments on photos of the bones. Moreover, their research lacked the rigor of multiple person blind testing. The arguments were easily fielded. The paper was rushed forward in a scientifically unjustified hurry.