William H. Calvin, A Brain for All Seasons: Human Evolution and Abrupt Climate Change (University of Chicago Press, 2002). See also http://WilliamCalvin.com/BrainForAllSeasons/Kari.htm.
ISBN 0-226-09201-1 (cloth) GN21.xxx0
Available from amazon.com or University of Chicago Press.
Webbed Reprint Collection|
William H. Calvin
University of Washington
Rift Valley is beautiful and amazing, well beyond my powers of
description. Driving north
from Nairobi on the old road is spectacular.
We are now, thanks to some advise from Meave Leakey, well above
the present shoreline of Lake Elmenteita near a quarry. The lake level used to reach up past here, in the good old
days, hundreds of meters higher than the present levels of Lake Nakuru
and Lake Elmenteita.
And this ancient shoreline is what made Kariandusi into another
version of what we saw at Olorgesailie yesterday:
here, too, there is a Leakey-excavated sea of handaxes.
Except that here, you can easily see one layer atop another.
And then another, like a layer cake.
My cousin, primed by seeing Olorgesailie and now knowing what to
look for, is gratifyingly amazed. Kariandusi is about the same age as Olorgesailie, with
estimates ranging from 700,000 to a million years old, right in the
middle of Homo erectus time.
Together, Olorgesailie and Kariandusi give you a wonderful
lesson in why erectus toolmaking is so enigmatic.
And why climate changes moving lakeshores might be so central to
understanding Homo erectus.
As at Olorgesailie, there is a fine one-room museum at
Kariandusi, another branch of the National Museum of Kenya which runs
this site. The museum here
has the same hominid skull casts seen in Nairobi (and
in museums around the world). It
also has a nice short version of how the Rift Valley formed in
geological time, the floor dropping down between two cracks (the two
escarpments we see mark, naturally, the two big north-south fault
lines) as the rift widened. The
walls of the valley have a lot of fossils exposed in some places.
The museum appears to train the guides well.
If some of what they say about handaxes is implausible, it’s
only because they are faithfully repeating what archaeologists have
said over the decades (sometimes, one suspects, with tongue in cheek).
Kariandusi museum has a poster full of the proposed uses of the
handaxe. It shows you the
extremes to which archaeologists have been pushed, trying to find some
definitive use for the strangely-shaped handaxe which is the defining
hallmark of Homo erectus culture.
They all have uses for it – and they’re probably mostly
correct, too – but none adequately explain why its shape is what it
is, or why that shape escapes the usual cultural drift for close to 1.8
Many modern archaeologists are suspicious that they might be
dealing with a blind-men-and-the-elephant situation when it comes to
the handaxe, that they possess only part of the truth and are making
erroneous extrapolations. They
just don’t know what to replace or supplement them with.
Because of the history of inadequate explanations, most have
become totally skeptical of any new explanation that is offered for the
handaxe, even by fellow archaeologists.
Been there, done that.
The handaxe poster starts with “For butchering.”
Yes, one edge of a handaxe could be used for clearing meat from
the bones. But why is the
back edge sharpened too, the one the hand has to wrap around? I’ve never heard an answer to that one. And why use an elaborate tool when a simpler one usually
suffices? Why use such a
symmetric, hard-to-make tool for a purpose that one of Glynn’s
half-rocks or random flakes would suffice for?
It’s overkill, as the phase goes.
The handaxe sure wasn’t designed for just defleshing.
“For digging up edible roots” reads the next panel.
That’s even more difficult when the implement is sharpened all
around the perimeter, because you tend to pound on roots. You’d break many handaxes that way (not to mention cutting
the palm of your hand). And,
in any event, overkill again. There
are some sturdy bifaces called “picks” that might stand up to
cutting roots loose, but here I am concerned with the classic,
enigmatic handaxe shape, not what broken or tumbled versions of it
might secondarily prove useful for.
“For scraping animal hides.” (Clothing, so early? Well, just assume they mean skinning the beast to get at the limb meat.) I’d sure prefer something with a comfortable grip, myself. And one of Glynn’s flakes or half-rocks would work pretty well for skinning. It doesn’t even have to be particularly sharp for skinning, so long as you maintain tension by lifting the hide loose as you separate skin from fascia. When I learned my surgery, one of the big surprises the first week was how handy dull tools were, that you often wanted to use the dull side of the scissors to spread, or the blunt handle of the scalpel to scrape, rather than the sharpened surfaces. Only beginners think that the scalpel is the quintessential surgeon’s instrument. Once you get through the skin somehow, surgery is mostly about spreading and separating along natural planes, such as between fascia and skin, where a sharp edge is a royal nuisance most of the time.
“As a core from which tools were struck.”
That’s a good possibility, at least for the larger handaxes
that lack fine retouching and show cavities where a flake used to
reside. But it doesn’t explain the bilateral attempt at symmetry,
or the tendency toward a point.
“As an anvil.”
Now there’s a trivial one.
Any flattish rock that was carried around would do, of course. No design needed. But
if you were carrying around a designed rock that was flattish and
sturdy enough – sure, why not use it as an anvil, should you need to
soften up a root or crack a nut?
“Thrown discus-style as a weapon.”
Now we’re talking. Throwing
has great possibilities in human evolution.
But the museum’s artist got it all wrong, as the cartoon shows
an over arm throw at a lone antelope, the handaxe’s pseudo-point
conveniently facing toward the animal, miraculously stabilized in that
unlikely orientation without the aid of a spear shaft.
But at least “discus-style” was included in the caption,
what I think is the key to the puzzle.
you can see why it’s been called the “Swiss Army Knife of
the Paleolithic.” If no
single use can justify its design, maybe it is a composite tool! Or so the story goes (that phrase “jack of all trades and
master of none” comes to mind).
Yet, ironically, the name “handaxe” is a misnomer because
using it as a handheld axe is the least likely of its proposed uses.
In its classic form, it is sharpened all around its perimeter.
It is thus likely to bite any hand that held it, if striking
something with any force. So
put scare quotes around “handaxe” from here on, whenever I forget
Furthermore, almost none of the proposed uses account for its
distinctive shape. Certainly
not simple butchering. It
could easily have been used as a core, from which smaller flakes were
made, and there is some evidence for this use.
Unfortunately, many handaxes have so much fine finishing –
tiny chips removed here and there – that it is clear that such
handaxes were something more than merely a core for thumb-sized flakes.
Yes, hacking, scraping, and cutting are possible uses (and there
is even some edge-wear supporting woodworking) – but the handaxe
wouldn’t have done those jobs better than Glynn’s broken rocks with
a fortuitous edge. And they (and the Oldowan tools) are sure a lot easier to
make, and they all continued to be made (the handaxe didn’t replace
And why is the handaxe flattened and bilaterally symmetric, with a suggestion of a point? (It is, however, seldom sharpened to a penetrating point, the way you see in the spear tips and arrowheads in the last ice age.) None of the Swiss Army Knife explanations ever get around to addressing such handaxe issues.
Even worse, this classic shape persists for nearly 1.8 million
years, even into Africa’s Middle Stone Age about 100,000 years ago. It is seen in Africa, Europe, and now even in China.
It stays about the same shape,
regardless of what local rock is used.
That really suggests we’re missing something important.
To conserve the classic form through the vicissitudes of
cultural drift and local fashion, there must be something that keeps
the shape drifting back toward some functional optimum.
But for what function? It’s
surely not the Swiss Army Knife functional collection, as combination
devices are surely subject to drifting styles, with features being
omitted when they are no longer supported by the culture.
I suspect that I wouldn’t have told you all this if I didn’t
myself have a candidate for what the prime use was, the one that none
of the Swiss Army Knife uses adequately addresses.
It builds on some experiments that Eileen O’Brien did back in
1979, the most unsettling undergraduate thesis I have ever seen. And since it meshes nicely with the waterhole aspect of the
savanna story that I’m trying to get across, perhaps I should tell
the updated version of my handaxe story.
I first hatched my handaxe scheme back in the 1980s, someone
immediately attached the name “Killer Frisbee” to it. Just try throwing a handaxe, even with the initially
horizontal plane of rotation favored by most modern Frisbee throwers,
and it will soon turn on edge and come down vertically.
Happens even to experts, not just me (I repeated O’Brien’s
experiments a decade later, also employing a well-trained discus
thrower). Doesn’t matter
how you throw it – overhand, sidearm, underarm – the same thing
are vertical-plane spinners.
Unlike round Frisbees, a handaxe will not lead you on a merry
chase after landing, rolling along forever.
The handaxe’s “point” will shortly bury itself in the
ground and bring the implement to a shuddering halt.
Is this good for something?
Some context must be missing, and it’s not likely to be a
prehistoric game of paleofrisbee.
The context, I suggested back at that Portugal meeting, is when
throwing such an object into a tightly-packed herd visiting a
waterhole, especially during a drought when their choices in watering
sites are very restricted and they try the safety-in-numbers strategy.
Then the puzzle parts seem to fall together.
I don’t think for a moment that the handaxe was a
general-purpose hunting projectile (the archaeologists are rightly
skeptical of that use). I
think that you can understand the handaxe only in the special-purpose
context of closely-packed herds at the waterhole.
me start with a few words about
shoreline predation, surely a topic of general importance for hominid
evolution, not merely the handaxe enigma. The big cats, as well as various other carnivores, have all
discovered that lakes, rivers, and waterholes are a good place to hang
out. That’s because the
grazing animals eventually have to visit a water source.
Wait for the animals to come to you.
Saves chasing them, and all that effort. Hominids would have realized the same thing.
(Recall what the bank robber said when asked about why he robbed
banks: “Because that’s
where the money is.”)
Of course, after a few successes, the herd gets a little wary
and picks another watering site. But
sometimes there isn’t another choice.
Some waterholes are obligatory, as all the others within walking
distance have become mud holes, suitable only for elephant beauty
baths. And so each
evening, the herd, packed tightly together for mutual protection, comes
down to the waterhole. The
tails of the waiting predators begin to twitch in anticipation.
Sometimes there were tailless predators instead, of the hominid
Being on the outer rim of the herd is not the best place to be.
Packing tightly does reduce the percentage of the herd that is
exposed to predation. The
bigger the herd, the bigger the perimeter – but the perimeter grows
more slowly than the area, and so, in the larger herds, only a few
percent are actually exposed to an attack.
With only a dozen animals, half of the herd is exposed.
An upright hominid might have been able to get closer to the
herd than the familiar four-legged carnivores.
But, as I earlier mentioned, the two-legged advantage doesn’t
last long. The herd will
increase its approach distance – the distance from which they start
moving away from you, if not running away.
And besides, what’s the hominid going to do, anyway – get
close enough to club a hapless animal?
So there’s the scene: tightly-packed
herd visiting waterhole, two-legged wannabe predator standing at some
distance, without even a tail to twitch.
What happened next?
entry-level solution, I said back at the Portugal meeting, was
to throw a tree branch into the midst of the herd (chimpanzees like to
wave and fling branches, so maybe our ancestors did too).
The herd will panic, of course, wheeling around to flee. The branch lands in their midst (towards the rear is best),
perhaps hitting an animal, perhaps not.
But soon an animal trips over it or gets entangled, knocked off
its feet by adjacent stampeding animals.
It tries to get back on its feet but another knocks it down in
the confusion. Pretty soon
it gets halfway back on its feet, but it is too late.
Two-legged predators arrive and grab it.
Maybe they club it, maybe four just cooperatively hold a leg
each in the chimpanzee manner while a fifth chews on its throat.
One way or another, they make a meal of it.
The bigger and more tightly packed the herd, the better the
technique works. The usual
surface-to-volume ratio advantage of herds and schooling is turned on
its head by this simple invention, of lobbing a branch over the top and
into their midst. The bigger the herd, the easier it is to disable one in the
Pretty soon, herds grow wary – but they form bigger and more
tightly packed groups in response, making the technique work even
better. The local trees
are denuded of convenient branches.
While waving and flinging branches are clearly favorite scare
tactics of chimpanzees (they have not been seen to use accurate
throwing for predation per se), they will resort to clods of dirt and
rocks when branches are in short supply.
Rocks, the hominids might have noticed, will go farther than
anything else. The thrower
can launch while still outside the approach distance.
But what does the rock buy them?
Few animals will trip over it when fleeing.
With a beginner’s throw, knockouts are unlikely.
Ah, but the herd is, remember, tightly packed in this scenario.
Even with the beginner’s side-of-the-barn throw, a lob can’t
miss hitting some animal somewhere.
If the rock is big enough and the animal small enough, even a
rock landing on the flank will bowl over the animal.
Were it not for the rest of the herd running past at close
quarters, the downed animal could likely get up and run away in time.
Few would be injured enough to stay put.
But the herd is running past, and attempts to get back up in
time may fail. Another
hominid meal is procured.
Rocks are more reusable than branches, which get trampled into
mere sticks. Are some
rocks better than others for this tightly-packed-herd use?
you had an outcrop of sedimentary rocks that was layered, so
some rocks were pre-flattened in the manner of slate.
Throw one of those and you’d get some of the frisbeelike
farther. Lands on edge,
too. Sometimes on an
That has an interesting neurological consequence.
All mammals have flexion reflexes, used to withdraw the body
part from further harm. If
you step on a thorn, you quickly withdraw your foot and shift your
weight to your other foot, all before your brain even takes notice of
the thorn. Most archaeologists know this, but what they might not know
is that withdrawal reflexes also work for damage to other parts of the
body – such as the back or flank.
If a grazing animal felt something sharp on its back (as from
overhanging thorn trees, with acacias common hereabouts), it would tend
to sit down quickly. The
big cats may have discovered this reflex tendency to crouch, given how
they leap onto an animal’s back and dig their claws in.
So flat stones with sharp edges might get a reputation for being
more effective. If you are
also knocking off sharp edges from such a stone to butcher the animal,
it might have some sharp edges for next time.
Two uses for the price of one.
The preferred projectile is now basically flat with sharp edges,
somewhat symmetric for less tumbling en route.
But it doesn’t necessarily have a point.
Why add a suggestion of a point, without making it really
pointed for penetration?
Some would have been semi-pointed, of course, perhaps as a
consequence of all the flaking used for butchering.
Or perhaps just from breaking off a segment (some would be
trampled by the herd, after all, and then recovered).
And the hominid hunters might have noticed that a bit of a point
made the stone more effective in bringing an animal down.
(You don’t have to understand the flexion reflex to make an
empirical observation about effectiveness.)
Some of the stones would just bounce off the animal’s back
without toppling it. But
those flat rocks with a bit of a point, given that they are spinning,
will soon embed their pseudopoint into a pushed-up roll of hide.
There’s no need to penetrate the skin.
Why does it work better at toppling the animal?
Because it stops the spinning stone, before it can bounce free.
Most throws will not strike the flank solidly, transferring all
their momentum to the hapless animal.
Most will bounce off the animal’s back, slowed only slightly.
But with the pseudo-point catching the roll of hide, all of the
stone’s momentum is transferred to the animal, rather than the usual
Because of that, even palm-sized handaxe-shaped stones may be
effective at toppling the animal.
The momentum transfer gets the animal moving slowly sideways,
and the pain’s flexion reflex (also enhanced by the abrupt jerk when
the point catches a roll of skin) interferes with the farside leg
extension that usually prevents toppling. Over it goes, ever so slowly, knocked off its feet.
Thus the classic features of the handaxe – somewhat flattened,
mostly edged, mostly symmetric, somewhat pointed – ought to be one of
the nice solutions to this hominid version of the waterhole predation
game. They’d surely retrieve and reuse favorite projectiles, of
course. However, given how
deep the mud is around those waterholes, they would probably lose a lot
of them, too. Over the
years, quite a few handaxes would accumulate in the shoreline mud.
That’s surely a better explanation for accumulations like
those at Olorgesailie than that the sites were some sort of factory,
doing an early form of mass production of handaxes.
It does suggest that the flattened teardrop is a pragmatic
shape, not necessarily some innate symmetry in the mind of the
toolmaker. Even the
more-of-less spherical “hammerstones” were shown by the
archaeologist Nick Toth to be a consequence of repeated use, not
design. Any stone tends to
become round, once you used it long enough.
As the “perfect” sphere in the mind went, so may the
The Killer Frisbee use might also help explain why a few
handaxes are found standing on edge in old watercourses and lake edges.
I doubt the handaxes were planted that way, just to serve as
primitive sundials or to confuse latter-day archaeologists. Thrown handaxes always land on edge, digging themselves a
nice groove and often planting themselves in a vertical orientation,
though most surely topple over during subsequent erosion of the
landscape, as when they are tumbled by stream flow.
layers here at Kariandusi make my point even more dramatically
than the sea at Olorgesailie. In
each layer of old lakeshore silt and mud, there are hundreds of
hand-sized stones showing signs of prehuman modification, most of them
classic handaxes. The next
layer a few centimeters below (exposed a little farther downhill) and
you see the same thing again. And
again. It reminds me of
the old jailhouse story of sending a prisoner a cake with escape tools
baked inside. Well, each
layer of this “cake” is loaded with an unbelievable number of
If the waterhole predation theories of handaxe use are even
partially correct, there ought to be a series of concentric rings of
handaxes, layer by layer down towards present-day Lake Elmenteita,
shrunken from its former self. Well,
perhaps not whole rings, as only certain sites on the lake’s
perimeter would be favored by both animal trails and hominid hunting
habits, but in any event there should be a lot of sites, given a
million years worth of Homo erectus families to feed.
Some Kariandusi handaxes appear somewhat smoothed, as if tumbled
in flowing water – and their edges wouldn’t bite the hand that held
them, making it possible to use them as a handheld axe of sorts.
But adjacent ones may have sharp edges, as if never moved
downstream after being lost. Hmmm.
Remember that floods happen, and climates eventually change.
a river flows faster than usual, it can cut a deeper channel and
so strip off layers of sediment from its banks and bottom. New river banks appear, showing off layers of smoothed
cobbles from several earlier river beds.
These are a common sight to anyone who hikes along a river today
and looks at the river banks, and it would have been much the same a
million years ago. But
here, some of those rock layers wouldn’t be just cobbles.
Guess what might be left exposed after all this down-cutting?
The river banks and bottoms would contain overwhelming numbers
of symmetric, pseudo-pointed rocks.
Some such “handaxes,” of course, would have been eroded out
and carried downstream and tumbled smoother.
Such tool-studded river banks would become known as Handaxe
Heaven in whatever language the locals had attained.
Would these early humans have called it “manna from heaven”
or ascribed this bounty, perhaps, to their ancestors having provided
It lends a whole new layer of interpretation to objet trouvé.
(I can hear it now: “No,
this tribe didn’t actually make handaxes, they merely recycled
the lost ones of an earlier culture.
Recycling is a million years old.”)
And it shows you a wonderful route to reinvention.
Techniques are always getting lost, much as the Australian
aborigines in Tasmania eventually lost some fire-making and tool-making
techniques over the millennia, once rising sea level had isolated them
from the mainland. Cultural
loss is one of the hazards of the population downsizing and
fragmentation that climate change can cause.
Riverbank hunters, however, with no more than just the
chimpanzeelike tendencies to lob rocks when a branch wasn’t handy,
could easily rediscover the aerodynamic properties of the handaxe and
become superstitious about using the “right shape.” When the provident riverbanks were depleted, they might start
reshaping local rock into the classic shape.
They’d already know, from long use, that the shape was useful.
It’s one reason why the classic shape might have survived a
million years of climate change and all the island-like fragmentations
of Homo erectus populations that repeatedly happened.
Mining “handaxes” likely also occurred from sites which were
no longer riverbanks, sites like Olorgesailie and Kariandusi are today. You can consider it as either the beginnings of mining or of
archaeology. “Making use
of the past” is a modern museum motto but you can see how it might
have gotten started.
There’s another kind of reuse of
handaxes, too. Consider
the life history of the classic handaxe shape: if not lost first, most
classic edged-all-around handaxes will eventually be broken, thanks to
landing on something hard or herds trampling them.
The handaxe might lose a third of its sharp perimeter.
If thrown in the usual manner, it would tumble and not go as
far, nor land on edge in the preferred manner.
But the remnant’s broken edge would be more amenable to a hand
grip. Now you could use the remaining sharp edges for all of those
Swiss Army knife tasks that the archaeologists proposed in their
frustration: pounding roots, defleshing, and so forth.
Ditto for the tumbled handaxes, smoothed to make them safe for
the palm of your hand. So
no-one even has to give up a favorite theory.
It’s not often when you can have your cake and eat it too. Just remember that the handaxe has two lives, if not
irretrievably lost in the lakeshore mud:
Frisbee first, Swiss second.
On to the NEXT CHAPTER
Copyright ©2002 by
Book's Table of Contents
All of my books are on the web.
out-of-print books are again available via Authors Guild reprint