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I assume you know what Stonehenge is.
00:00:01
It’s those big, mysterious rocks in England.
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And when there’s a mystery,
we humans want to solve it!
00:00:06
Researchers have been studying
Stonehenge for hundreds of years now,
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and it turns out that we actually
know a thing or two about it.
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Or in this case, we know seven things about it.
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[♪ INTRO]
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Stonehenge is a ring of giant standing stones,
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and it is so ancient that most of those
stones have fallen or been lost to time.
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The Stonehenge you can go
and visit today has more than
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90 visible stones or stone fragments.
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Look, I would love to tell you
the exact number of stones,
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but we’re going off a diagram for this estimate.
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And SciShow’s budget does not
include round-trip tickets
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to Stonehenge for me to go
count them all in person.
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The arch-like structures are called trilithons,
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which is just a word for two upright stones,
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with one horizontal stone called
a lintel balanced across the top.
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They’re made of huge, carved
blocks of sedimentary rock
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called sarsens or sarsen stones.
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The other half of the stones that
make up Stonehenge are a different,
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smaller variety called bluestones.
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Bluestone is kind of misleading,
because they only sort of look blue-ish
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when they’re wet, but we’ll give
whoever named them a pass this time.
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Stonehenge was built and used
by different peoples in phases
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over a span of roughly 1500 years,
from about 3000 BCE to 1500 BCE.
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The sarsens and bluestones were
brought from all over what’s now
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known as the United Kingdom, and
arranged and rearranged over time.
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But I don’t want to get ahead of myself!
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Now that we are on the same
page, here are seven very
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weird facts about the most famous
circle of stones in the world.
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First is a little bit of a weird
one...some semantic pedantry for you.
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Stonehenge… isn’t a henge!
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A henge isn’t just some fun English slang,
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it’s a specific archeological term that refers to
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a type of structure that was
constructed between 3000 to 2000 BCE.
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It’s basically a big ring of dirt
with a gap in at least one section,
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kind of in the shape of a
horseshoe or a power button icon,
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and there’s at least one
deep ditch along the inside.
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The hundred or so remaining henges in
Britain and Ireland range from as small as
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a tennis court to several hundred meters across.
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They can be made up of concentric
hills and valleys of dirt,
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but the order is important!
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While Stonehenge was originally a dirt
ring constructed around the same time
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as true henges, many researchers
think of it as more of a “proto-henge”
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because the main ditch is outside the piled dirt.
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So maybe more of a practice run
for the henge-building peoples.
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Now the name isn’t totally off-base,
or at least the first half isn’t,
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since all the structural components
of Stonehenge are stones.
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And that’s more meaningful
than it sounds actually.
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Most people use the words stone
and rock pretty interchangeably,
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but archeologists typically use rock to
mean the original chunk of Earth and stone
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to mean a rock that humans have
moved, modified, or used in some way.
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This makes sense to me but I never
thought about it until just now.
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And all of the sarsens and
bluestones that make up Stonehenge
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definitely fit that definition of stone!
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Alright, now here is where
this fun fact takes a twist.
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Even though it’s not a real henge, all
henges are actually named after Stonehenge.
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Like, the reason we have the word
“henge” is that it comes from what
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everyone was calling Stonehenge back
before archaeologists got involved.
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In linguistics, this is called a back-formation,
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where you take part of a bigger word
and then make that new bit its own word.
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The name Stonehenge probably came from
the Germanic phrase “stan-hengen,”
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which means “stone hanging” or stone gallows.
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So we think “henge” could describe those
horizontal lintel stones hanging in the air,
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or implies that trilithons
kind of looked like gallows.
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Some of the oldest evidence
that we have of the word “henge”
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being written down was a shortened
form of Stonehenge in a 1792 poem.
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And it’s kinda just like how every
scandal is a “-gate” these days,
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from like Gamergate to Deflategate,
we started naming circular monuments
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made of upright things after Stonehenge,
including the nearby Woodhenge.
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Woodhenge was actually constructed around
the same time out of rings of timber
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and dirt, but it’s been
overshadowed by its stonier cousin.
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In any case, archeologists started using
the word “henge” as a standalone term
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in the 1930s to refer to the
thing that is identical between
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both Stonehenge and Woodhenge,
which is the dirt rings.
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Which is how the namesake of a henge got
kicked out of its own club of henges.
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But Henge-gate isn’t the
only time that archaeologists
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have gotten interested in Stonehenge.
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We have records of people studying
Stonehenge going back hundreds of years,
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and they basically haven’t stopped since.
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The earliest written accounts
were made when wealthy men,
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sometimes called
gentleman-scholars or antiquaries,
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went around exploring
historical sites and documenting
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whatever they found interesting.
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For instance, the antiquary John
Aubrey did a pretty accurate site
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drawing of Stonehenge in 1666, while
William Stukeley published a book
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in 1740 made up of his observations of, quote,
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”those remarkable circles of Stones
which we find all over the kingdom.”
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Stukeley spent a lot of time at Stonehenge and
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first used the term trilithon
to describe its iconic arches.
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And he’s also credited with first documenting how
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the summer solstice sunrise
aligns with the monument.
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Aside from, you know, the
people who made it that way,
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they also were aware of that.
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The list of past and present
archeologists studying Stonehenge is long,
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and they’ve investigated all
kinds of questions about the land,
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the stones, and the people
who cared about this monument.
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But not all scientists who
visit Stonehenge want to know
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about the site itself … some
come for the earthworms.
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Charles Darwin’s last published
scientific book was about earthworms
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and how they interact with soil.
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Yes, that Charles Darwin.
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And some of his studies in the mid-1800s
involved the Stonehenge sarsens.
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He knew the stones were above
ground at some point and had fallen
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and then were buried in soil over time,
possibly due to the worm activity.
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As they ate organic matter
and pooped out castings,
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they basically built new soil
layers on top of the old stones.
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So not only is Stonehenge’s
legacy a long and impressive one,
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so is the legacy of archaeology on Stonehenge.
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A little meta, isn’t it?
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But solving Stonehenge’s mysteries
requires funding, and so do we.
00:06:20
So here’s a quick ad break!
00:06:22
Thanks to ACT for supporting this SciShow video!
00:06:25
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You can learn more about the ACT or
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at act.org/scishow, the QR code,
or the link in the description.
00:07:08
While Stonehenge has been a topic
of research for hundreds of years,
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it’s also been the focus of changing ideas about
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conservation of important archaeological sites.
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And that starts with who even owns it.
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Because for the vast majority of
its time in the modern record,
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it was on private property.
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A man named Cecil Chubb bought the
land where Stonehenge sits in 1915,
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and three years later, gave the land
as a gift to the nation of England.
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Which was nice of him, since it
meant that researchers would have
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a lot more access, and the government
could help protect the monument.
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But if you look at older photos or illustrations
of Stonehenge from around that time,
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you might notice that they only sort of
look like the pictures you’d see today.
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Like, this 1835 watercolor by the
artist John Constable looks a lot more,
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uh, crumbly than picturesque.
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And that’s because alongside
carefully excavating Stonehenge,
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there have been lots of restoration
attempts, with mixed results.
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Throughout the 1900s, people
used heavy engineering equipment
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to restack trilithons, replace fallen lintels,
and straighten out crooked bluestones.
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And they’ve had to do this a few times.
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So after they got tired of needing to
restack the world’s heaviest Jenga blocks,
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they came up with a more permanent solution.
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The bases of many wobbly sarsens were set into
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poured concrete foundations to hold them upright.
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I feel like this isn’t gonna be great...
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These restorations were proposed
and supervised by some archeologists
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who had conducted excavations at Stonehenge.
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But this restoration has
been criticized in hindsight.
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Some current archeologists have emphasized that,
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now that we’ve made these changes,
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we owe it to visitors and researchers
alike to publicly acknowledge the ways
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that Stonehenge has been changed and
it isn’t a time capsule of the past.
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And because concrete is concrete,
these are changes we can never undo.
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There’s no take-backsies in
excavation, or in concrete pouring.
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As we continue to excavate and
study the stones of Stonehenge,
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we’re learning more about their composition too.
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And it turns out that the bluestones make
distinctive sounds when they’re thumped.
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There’s even some evidence that the
people who put them there knew that!
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See, we have known for a long time
that these bluestones were special.
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While the sarsens of Stonehenge were
hauled from around 25 kilometers away,
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the bluestones may have been brought
here from more than 200 kilometers away.
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So obviously a big question for
archeologists has been: why?
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Why were these bluestones so important that people
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put in the effort to move them so far?
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One hypothesis is that there was a pre-Stonehenge
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circle of bluestones constructed in Wales.
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Then, around 3000 BCE, they were all moved,
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right around the same time Stonehenge
would’ve initially been constructed.
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So maybe a migrating group of people
wanted to bring their monument with them.
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Other bluestones may have been brought over
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in a more piecemeal fashion, though.
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And another group of researchers
hypothesized that these bluestones
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were specifically sourced because
they’re a kind of lithophone—
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a rock that makes like a pretty,
resonant sound after it’s hit.
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We’re still not actually sure why
certain rocks ring while others don’t,
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beyond the fact that it has to
do with their internal structure,
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which allows sound waves to propagate.
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Most rocks just make a dull
“thud” when you hit them,
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because they dampen those vibrations instead of
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conducting them or amplifying them.
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The stones themselves have
little impact dents on them, too,
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which leads some to suggest that they might’ve
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been chosen for their musical properties.
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And, of course, it’s hard to tell
exactly what these bluestones
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would’ve sounded like, or what
else they were used for before the
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earthworms half-buried them or they
were reconstructed with concrete.
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But all this suggests that Stonehenge
may be the birthplace of rock music.
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It sounds like a major undertaking to move
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many of these huge rocks 200 kilometers.
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But as unpleasant as that must have been,
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hauling Stonehenge’s Altar Stone was even worse.
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The Altar Stone is the name of one
of the central giant stones with
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a mass of around 6 metric tons.
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It’s mostly buried underground,
and no, we don’t actually know
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if it was ever used as an altar.
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We think it may have gotten its modern name from
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an offhanded speculation
from an English architect.
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And, according to a paper
published in August 2024,
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the Altar Stone may have been
brought to this site from more than
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750 kilometers away, from a
site in what’s now Scotland.
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To figure this out, researchers
extracted a couple of different minerals
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from the stone called zircon, apatite, and rutile.
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All three of these minerals sometimes
contain trace amounts of uranium atoms,
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which radioactively decay
over time into lead atoms,
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and that can help us estimate the
age of the rock they’re embedded in—
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up to millions or billions of years.
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Some of the mineral grains they tested
were around 450 million years old,
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while others were around a billion years old.
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And this combination matched the
composition of rock in the Orcadian Basin
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in northern Scotland, which
is about as far as you can get
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on the UK landmass from
Stonehenge in southern England.
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And you thought moving a couch
into your new place was hard!
00:12:13
It was, you did great.
00:12:14
So we know a lot about how
the rocks got to this place.
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But we know less about the people who moved them.
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Many groups of humans who lived
in the area during the early
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phases of construction were semi-nomadic,
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meaning it can be hard to find evidence
connecting them to Stonehenge directly.
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Plus, when it came time to bury
the dead, some of these cultures
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opted for cremation as opposed to burial,
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so there aren’t always remains
for researchers to study.
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Fortunately, DNA evidence can help.
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Molecular biologists are taking some
educated guesses with the human bones
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that we do have, especially the ones
that were buried near Stonehenge.
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The biologists isolate as much usable
DNA as they can, make lots of copies
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of the fragments, and then read
the sequences of DNA base pairs.
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They use computers to catalog all
of this data in a DNA library and
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stitch overlapping fragments
together as best as possible—
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like puzzle-pieces in a giant terrible
puzzle that only a computer could do.
00:13:12
Then, they can look for genetic markers
like single nucleotide polymorphisms
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or SNPs, which are DNA base
pairs that vary between
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different individual humans or populations.
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And by comparing these new DNA
libraries to existing DNA libraries,
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they can get a sense of what groups are
00:13:29
most similar to the remains
that were found at Stonehenge.
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The DNA evidence from nearby burials
suggests that early phases of
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construction at Stonehenge may have
been the work of two groups of people:
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The Western European hunter-gatherers
and the Early European Farmers.
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And there’s also evidence that when another
group called the Bell Beaker culture
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moved into the region, they started to
use Stonehenge as a cultural hub too,
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even though they had nothing to
do with its original construction.
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The DNA also suggests that when
the Bell Beakers came to town,
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they didn’t merge with the other
indigenous groups right away.
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Instead, both groups stayed friendly,
non-interbreeding neighbors for
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hundreds of years before their
populations eventually merged.
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Obviously there’s still a
lot missing from this story,
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but it’s cool to think about how
Stonehenge brought these people together.
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There is still plenty we do not know about
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the humans who built and
interacted with Stonehenge.
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So if you’re looking for mysteries,
Stonehenge certainly has them.
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But it’s just as important to
reflect on all the progress we have
00:14:32
made in de-mystifying this
incredible, weird monument,
00:14:36
all without any written records. Go, science!
00:14:40
[♪ OUTRO]
