My latest Mind and Matter column in the Wall
Street Journal:
Obsidian was once one of humankind’s most sought-after
materials, the “rich man’s flint” of the stone-age world. This
black volcanic glass fragments into lethally sharp, tough blades
that, even after the invention of bronze, made it literally a
cutting-edge technology.
Because sources of obsidian are few and far between, obsidian
artifacts are considered some of the earliest evidence of commerce:
Long-distance movement of obsidian, even hundreds of thousands of
years ago, suggests the early stirring of true trade.
Differences in the trace elements in each volcanic source let
archeologists trace the origin of individual obsidian artifacts and
reconstruct trade routes. A new study, by Ellery Frahm of the
University of Sheffield and Joshua Feinberg of the University of
Minnesota, has used such obsidian tracing to shed light on
how trade collapsed in the Akkadian empire of the early Bronze Age
around 4,200 years ago in what is now northern Syria.
In the 23rd century B.C., a usurper named Sargon became king of
Akkad and conquered all of Mesopotamia, but his empire collapsed
soon after his death. At a site called Tell Mozan, which seems to
have been “Urkesh”—the capital of the Hurrians, a people whom
Sargon conquered—Drs. Frahm and Feinberg uncovered 97 obsidian
artifacts from a palace and temple complex. The objects date from
before and after 2200 B.C., which is when the Akkadian empire
apparently disintegrated, as evidenced by the abandonment of cities
and a change in the variety and standard of pottery.
Three of the 97 obsidian objects came from sites much farther
west, places whose obsidian normally ended up being used around the
Mediterranean. This probably implies occasional VIPs passing
through, rather than regular trade. The remaining objects
originated from sites in Eastern Anatolia.
However, there was a dramatic change in the obsidian objects at
Urkesh around the time of the collapse. Before, the objects came
from six different sources in Anatolia, implying that Urkesh was a
cosmopolitan city visited by traders from different places.
Afterward, the objects came from just two of the nearer sites.
Moreover, using a new magnetic technique, Drs. Frahm and
Feinberg can identify which quarries at the two sites were used,
and they find that, after the collapse, different quarries were
being used from before. The obsidian thus confirms the suggestion
from pottery evidence that there was some sudden disruption at this
time and that trade atrophied.
Why? For many years the Akkadian collapse has been explained
according to the academic fashion of the time. The first culprit
was thought to be unsustainable agricultural practices, leading to
the exhaustion of the soil and the displacement of farmers by
shepherds. More recently, climate change has been blamed. A
megadrought supposedly resulted from global cooling, caused by
either a large volcanic eruption or a big meteorite strike
elsewhere on the planet. But the evidence for a global climate
event around this time is shaky.
A regional rainfall failure does seem to have happened, as
evidenced near Tell Mozan by changes in crops, river flow and the
disappearance of forests. Yet Karl Butzer of the University of
Texas at Austin argues in a new paper that pollen records and an increase
in contemporary canal building further downstream in the lower
Euphrates valley (implying an increase in available water) mean “it
is implausible that the Akkadian heartland collapsed because of a
megadrought.”
Instead, Dr. Butzer argues that Sargon’s conquest itself caused
the collapse of trade by destroying cities and disrupting what had
till then been “an inter-networked world-economy, once extending
from the Aegean to the Indus Valley.” In other words, as with the
end of the Roman empire, the collapse of trade caused the collapse
of civilization more than the other way around.