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- [Narrator] We are the paradoxical ape:
bipedal, naked, large-brained;
long the master of fire, tools and language,
but still trying to understand ourselves;
aware that death is inevitable,
yet filled with optimism.
We grow up slowly,
we hand down knowledge,
we empathize and deceive,
we shape the future from our shared understanding
of the past.
CARTA brings together experts from diverse disciplines
to exchange insights on who we are and how we got here.
An exploration made possible
by the generosity of humans like you.
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- Good afternoon.
Thank you Bahani, you're very kind.
We all know fire today as a source
of heat, light, protection,
a technological aid and a social enabler.
But it hasn't always been like that.
And at what stage did hominins lose their fear of fire
as something really dangerous?
Wildfire must have been a source of fire for early hominins,
and presumably they grasped it
and used it right there at its source.
But lightning is probably the most common cause of wildfire
in Africa, and it thus provides a seasonal source of fire.
But a very brief source of fire.
So in the early days, when hominids first made use of fire,
it would not have been very commonly.
We have to distinguish fire use as opposed
to the deliberate control of fire and its creation.
So the opportunistic seasonal collection of fire
from a natural source seems likely
for the earliest hominins,
but what we don't know is whether in those early times,
they could necessarily transport the fire,
feed it once they got it where they needed it,
and then maintain the fire for as long as they needed it.
As a sideline, it's quite interesting to note
that Raymond Dart, in 1948, named the three-million-year-old
Makapan fossils Australopithecus prometheus
and Job already mentioned that,
but he named them that after the mythological giant
that had stolen fire from the heavens.
And the reason that Dart named it that was
because there were some blackened bones associated
with the fossils in the sites.
And he thought that perhaps they were making fire.
But unfortunately, chemical tests quickly showed
that this was simply staining on the bones,
and so the name was discontinued
until recently resurrected by Ron Clarke
as the name for his new fossil Little Foot.
But of course not because Ron believes
that those fossils were using fire
but because of the morphological similarity.
We have only rare evidence for early fire use in Africa,
and I'm selecting three of the most famous
of the sites to demonstrate that:
Koobi Fora, Swartkrans and Wonderwerk.
So, Koobi Fora is at Lake Turkana in Kenya.
And it was excavated predominantly by Jack Harris.
The site is an open site,
and I make that point because it's important.
It's 1.5 million years old,
and Jack found burned sediment in the site associated
with burned stone and burned bone.
Many of the critics would have suggested
that perhaps wildfire swept through the site
and burned the traces.
But Jack points out that,
in addition to the burned bone and stone,
there are unburned bones
and stones in between those patches.
And so it seems most likely
that hominins exploited fire here,
though perhaps very briefly.
And at Swartkrans in Member 3,
which is one million years old,
Bob Brain found 270 pieces of burned bone
which he believes was evidence for fire,
pretty much directly below the grid that you see there.
And associated with those burned bones were bones
that had been used as tools that subsequently,
Lucinda Backwell believes, were used
for extracting termites out of their mounds.
Wonderwerk I think is particularly interesting
because this is a cave, and I emphasize that.
Caves are dangerous places where carnivores live.
And it would seem really unlikely that hominins
would be able to move in there without the use of fire.
And I emphasize always the difference
between the use of fire as opposed to the control of fire.
There's very little chance that fire
could have accidentally got into Wonderwerk,
because the fire traces here are 30 meters
from the entrance.
And this implies that the hominins
would have transported fire from its source,
perhaps wildfire, but the traces are ephemeral.
So fire probably wasn't maintained for very long
within the site.
Here is the stratigraphic evidence and micromorphology
from Stratum 10, one million years old.
And if you have a look over on the left there,
within the black box, you'll see the layers of ashes
that demonstrate that fire.
Alongside that, also there were burned bits of bone,
and FTIR, Fourier-Transform Spectroscopy,
demonstrates that burning of bone.
They were actually on hand axes associated with Stratum 10.
Now, there were no fossil remains,
but presumably the actor was Homo erectus,
also known sometimes in Africa as Homo ergaster.
Leaving aside those sites for the moment,
we must ask the question,
what evolutionary changes were taking place from the time
that we see the evidence for fire?
And is there any way of linking these changes to fire use?
Homo erectus appeared in Africa somewhere
between two and one-and-a-half million years ago.
That's certainly before we see the archeological evidence
for the traces of fire that I showed you.
But what is interesting is that compared
with earlier hominins, the brain size
of Homo erectus increased, and the teeth
and the gut size decreased, as Job showed you earlier.
Big brains are expensive tissues
and this increased brain size, yet reduced tooth
and gut size, imply that Homo erectus
must have had an enriched diet compared
with earlier hominins.
Now, there are competing schools of thought
about why the physical evolution took place at this time.
The first one is that hominins
may have become more effective at obtaining meat,
especially fatty meat.
Secondly, that hominins
may have processed food mechanically;
in the case of plants, to break down fiber;
in the case of animal foods, to break down tissue.
And thirdly, that hominins
may have cooked their food sometimes.
How likely is it that Homo erectus
sometimes used fire for cooking?
This claim is made in "The Cooking Hypothesis"
by Richard Wrangham in his wonderful book "Catching Fire."
And cooking would especially benefit the young
or the aged with deficient teeth.
(audience laughing)
But the sporadic archeological evidence
for fire use doesn't wholly support the cooking hypothesis.
But as archeologists, we recognize
that evidence may be absent for several reasons,
not least that preservation in many of the sites.
(audience laughing) So,
could she have cooked dinner some nights?
And more importantly, could Homo erectus have roasted tubers
like the Hadza do today?
O'Connell and colleagues in their Grandmothering hypothesis
suggest that there sort of being
a particularly cogent thing for older women to do,
that they would have improved the health and the well-being,
especially of children, by collecting tubers
and roasting them to break down that fiber.
And what is the earliest archeological evidence that we have
for roasting starchy plants?
It's certainly a long time after the presence
of Homo erectus.
Now, the African Middle Stone Age began
about 300,000 years ago,
and we don't get direct archeological evidence
for tubers even then.
But at Border Cave, which is now being reexcavated
under the leadership of Lucinda Backwell,
we see a Middle Stone Age archive that begins
about 227,000 years ago
and continues to about 43,000 years ago.
A stunning site, as you can see from this image.
And at Border Cave,
we have discovered starchy underground stems and corms
that were roasted from at least 160,000 years ago,
perhaps 200,000 years ago.
So in Members 5BS down at the bottom,
and Member 4WA, we have now more than 60 whole corms
or tubers that were roasted and preserved.
After about 200,000 years ago,
Homo sapiens in many parts of the world
developed pyrotechnology even further.
And this suggests that perhaps fire was now created at will,
that people had control of fire,
perhaps through percussion of rocks,
the strike-a-light method or friction of wood-on-wood.
But African archeology is silent on this matter.
We simply don't have evidence for that.
And yet we see increasingly sophisticated pyrotechnology
appearing through time implying
that fire should have been created whenever it was desired.
So I've chosen three South African sites
just to demonstrate some
of that rather complex pyrotechnology.
Down in the South, Pinnacle Point and Blombos.
And up on the East Coast, Sibudu.
Rocks were heat treated at Pinnacle Point 164,000 years ago.
And there at the bottom left you see a heat treated biface
from the area.
The heat treating of rocks improves their flakability,
it makes it possible to strike longer thinner flakes
and it makes it easier for the stone tool napper
to strike those flakes.
It also improves the quality of the rock itself.
And Blombos, the heat treatment of silcrete
about 75,000 years ago demonstrates
that it facilitated the pressure-flaking of points
to produce these long thin rather beautiful points.
At Sibudu, we see something different,
but it's much more recent.
By 72,000 years ago, people were making compound adhesive.
And Raman and EDS spectra show that both hematite
and carbon was part of the recipes.
And at 64,000 years ago,
gas and liquid chromatography confirmed
that there was coniferous resin
on some of the tools mixed together with hematite.
Now, adhesive needs low temperatures
for the drying and the hardening,
so fire is an important part
of the complex adhesive manufacturing process.
And temperatures were controlled through firewood selection
and the knowledge of how much wood should be used
on any given fire.
To sum up, the first use of fire
by Homo erectus were seasonally opportunistic.
The creation at will by Homo sapiens,
the creation of fire at will
by Homo sapiens probably started somewhere between 300,000
and 200,000 years ago in the Middle Stone Age.
And although we don't have direct archeological evidence
for this, increasingly sophisticated pyrotechnology
from this time suggests
that people must have controlled fire.
Now, in Europe we know
that Neanderthals were using manganese oxides
and various rocks to create
and strike fire, but we haven't yet found any
of that evidence in Africa.
I'm sure it's simply a question of looking for it
and that that's a story that will be told in the future.
In addition to the heat treatment of rocks
and adhesive manufacture,
people used fire to create medicinal smoke
through the careful choice of fire woods.
They used camp site maintenance by using fire
to clean up their bedding, for example,
and clean trash from their sites,
which undoubtedly would have improved the health
of the people who lived there.
They used fire for hardening of wooden tools,
and Hillary Deacon thought that they might have stimulated
the growth of fresh grass in the field
even during the Middle Stone Age to lure game to sites.
These and other hot topics (audience laughing)
are fuel for another day.
So, thank you.
(audience applauding)
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