12 SPRING 2020 / POPSCI.COM
STONE WAS CUTTING-EDGE
until about 10,000 years ago,
when our ancestors discovered
a better material from which to
fashion their arrows and axes:
copper. Archaeologists believe it
was the first metal manipulatedby human hands, and since then,
it has enabled some of our great-
est inventions. Now copper is the
third-most-consumed metal in
the world. These six technologies
show how it helped shape our
civilization over the millennia.TURN BACK TIMEBY GRACE WADE /
ILLUSTRATION BY WES L COCKXgo for
bronze
Coinage
Modern pennies contain only
2.5 percent copper (the rest is
made of much-cheaper zinc), but
some of the oldest-known coins
were bronze, which is up to 95 per-
cent copper. Copper provides lots
of corrosion resistance, keeping
change in shape as it passes hands,
and its malleability made it easy
to emboss with images of leaders
and other cultural symbols.Bronze
Copper is a fairly soft metal,
but you can mix it with others
to create tough alloys. Around
3000 BCE, Sumerians combined
it with tin to make bronze, which is
stronger, easier to cast into molds,
and better at holding a sharp edge
than either element alone. That’s
because pairing up sets of differ-
ently sized atoms makes it difficult
for them to slip past each other.Metallurgy
The oldest metal object
unearthed to date is a tiny 6th mil-
lennium BCE copper awl found
in the Middle East. Because it’s
commonly found as a pure metal
instead of mixed in ores, copper
was ideal for human’s invention
of metallurgy, the process of
smelting and casting metals.
This enabled early civilizations to
wield hardier axes and arrows.Electricity
Not only is copper the second-
best electrical conductor after
silver, but it’s also extremely
ductile, meaning you can stretch
it out into thin strands without
breaking it. Since Alessandro
Volta’s invention of the battery
in 1800, copper wiring has been
crucial to all things electric, from
circuit boards to the cables that
connect us to the internet.Copper roofing
We’ve been using copper to cap
buildings since the 3rd century
BCE, including in structures like
the Pantheon, because it can flex
into intricate pitches and designs
that rule out wood or tiles. The
material undergoes a chemical re-
action when exposed to open air
that results in a green outer layer,
which is more than just a charm-
ing color: It also prevents erosion.Antimicrobial surfaces
Copper is toxic to many single-
celled organisms, killing a wide
range of microbes—including
some that can evade our best
antibiotics— in two hours or less.
Some hospitals now take advan-
tage with door knobs and bedrails
made of the metal. This is an old
trick; healers prescribed copper
powder for ailments like ear infec-
tions and burns in ancient times.