Fire, like life, is only known to exist on Earth.
And humans are the only species that has fully
figured out how to harness all that firepower.
Even though some species need fire to create their favorite habitat
or to accomplish an important part of their life cycle,
they’re not, like, making it themselves.
Fire is an experts only gadget, and we are those experts.
Learning to get along with fire, benefitting from it,
harnessing it, took some time.
Like they say: you play with fire, you're gonna get burned.
And no doubt we did. Lots of us. Repeatedly.
Over the course of many thousands of years.
It is still happening today…
Eventually, fire became our thing.
But exactly when that happened is way more
of a mystery than you might think.
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To start off, let’s get a little background on fire itself.
The chemical reaction to make fire has only been possible
here on Earth since this planet got its oxygen atmosphere.
The earliest geologic evidence of wildfires is from about
430 million years ago, when atmospheric oxygen levels
reached the 16% necessary to sustain a blaze.
And obviously, that’s way, way before
any of us sentient apes were around,
meaning that all the fires that happened for hundreds of millions
of years were due to things like lightning strikes and volcanoes.
None of the OG fire users left us any diary entries,
so when and how we figured out how to harness it
is a surprisingly controversial question.
It's generally agreed that our ancestors started tinkering with fire
in Africa, since that’s also where our whole lineage first evolved.
And wildfires were pretty infrequent in Africa until between
7 and 8 million years ago when the tropical rainforests
began to dry out, and got replaced by grasslands –
an ecosystem in which high intensity fires thrive.
That’s around the same time and place that hominins
began to emerge, which a lot of experts think is no coincidence.
Fire-swept landscapes might have been appealing to our
ancestors because predators didn't like to hang out there.
But as the old maxim says, come for the absence of jaguars,
stay for the burnt rodent carcasses!
Wait, has no one else heard that one before?
And yeah, it's been argued that our species is defined
by our connection to fire early in our evolution.
At some point, being able to eat food cooked
instead of raw boosted our nutrition,
which was great for our ancestors' brain development.
In addition to growing big noggins by enjoying superior snacks,
fire gave us protection, warmth, and a focal point
for social gatherings and a forge to make tools.
So, it's one thing to casually benefit from a fire-dependent landscape,
but how exactly did a bunch of primates learn
to harness a grassland wildfire that was 380°C?
At first, they probably didn't.
Our ancestors’ first use of fire was likely opportunistic:
they’d just take advantage of whatever got left
behind after a naturally occurring wildfire swept through.
Smokey fires were easy to spot and follow around in the landscape,
and they made good places to ambush prey, not to mention
the protection they offered from predators and biting insects.
Hominins could have even fed these fires by adding their own fuel,
like more unburned brush or slow-burning animal poo.
Which I bet smelled awesome.
But the big question is when we started kindling,
sustaining and spreading fire around.
Anthropologists and archaeologists still aren’t sure they’ve found
the oldest evidence of human-controlled fire that might be out there.
So, what evidence do we need to figure out
when early humans became fire experts?
To answer this question, researchers first look for the same stuff
that signals the presence of Earth's very first fires: charcoal.
But since the charcoal residue from a wildfire
and a controlled fire look the same, you need more than that.
Hence, the controversy over when we
became proficient with the hot stuff.
In general, charcoal needs to show up along
with some other evidence in order for experts to agree.
One sign that the folks knew what they were
doing with fire is the presence of a hearth –
a ring of stone with charcoal that’s only found inside the ring,
as opposed to scattered around the settlement.
That shows that a fire was tightly contained,
and implies it was fully under somebody’s control.
Extra points for evidence of earth that was baked
at high temperatures, not just charcoal alone.
Baked earth would indicate that a fire burned
in one spot for a long time, and in order to keep that going,
somebody would need to add more fuel.
The site also needs to look like it was inhabited by hominins,
so a cave strewn with bones and tools is an ideal example.
Another way to tell whether fire was used
intentionally is the presence of heat-treated rock.
Turns out that treating your rocks with fire or heat
before whacking them into stone tools made the source material
easier to fashion into things like axes and spearheads.
But evidence of cooking in a settlement is
a pretty ironclad signal that some people
were able to use fire in a controlled way as a part of daily life.
Cooking sites are hard to dispute, because they often
check all the boxes archaeologists need to agree
that these people were fire professionals.
Some archaeological sites dating back at least
one million years have some of these characteristics, but not all.
Which is where the controversy comes in –
it's possible these scorched bits of earth were
just the products of wildfires that were neither
created nor controlled by humans.
Many researchers think that Homo erectus
may have been cooking with fire as far back as 1.7 million years ago,
based on evidence of them making hearths.
However, the evidence is sporadic,
indicating that they weren’t really doing this all the time.
Counter arguments say ​​that sure,
fire might have been used occasionally for a million or so years,
but our ancestors weren't barbecue pit masters
until a few hundred thousand years ago.
But how many hundred thousand years ago?
The oldest site showing pretty irrefutable controlled use of fire
is Gesher Benot Ya‘aqov in Israel, a 780,000-year-old settlement
on the banks of ancient Lake Hula.
No hominin remains have been found there,
but there are lots of fish bones, stone tools,
burnt seeds, wood and flint, and evidence of cooking.
It’s clear that multiple fires were lit on the same spot,
over an extended period of occupation.
Other sites like Tabun Cave in Israel show this at around
380,000 years, which really seals the deal on humans using fire.
But regardless of exactly when it happened,
we do know that once humans figured out how to use fire,
the hot stuff, there was no looking back.
We shape landscapes with it,
we cook all our favorite foods with it,
and we even invented the internal combustion engine
and began burning old fossilized plants, too.
Human time here on this planet has been made possible by fire–
this neat little trick only Earth can play.
And if what I said earlier about fires only being possible on Earth
for a few hundred million years piqued your interest, you’re in luck!
Our friends at Eons made a whole video about just that.
Go check it out, and all of their other great
paleontology and evolutionary videos, too.
Thanks for watching!
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