PHOTOS: GETTY X2RESOURCE A FEAST FOR THE MIND
Are we really breathing in some
of Caesar’s last breath?
The story goes that in 44 BC in Rome,
Julius Caesar was assassinated by a
group of his own senators, crumpling
to the floor with a final gasp. This last
breath contained around 25 sextillion
(that’s 25 followed by 21 zeroes) air
molecules, which would have spread
around the globe within a couple of
years. A breath seems like such a
small thing compared to the Earth’s
atmosphere, but remarkably, if you do
the math, you’ll find that roughly one
molecule of Caesar’s air will appear in
your next breath.
And it doesn’t stop there. In the
same way, you might currently be
inhaling Cleopatra’s perfume, German
mustard gas and even particles
exhaled by dinosaurs.SHARE A BREATH WITH CAESAR
With every breath, we inhale the story of our planet. Sam Kean, author of Caesar’s
Last Breath, tells us about the remarkable history of the air around us
What exactly are these air
molecules?
Nitrogen and oxygen are the main
ingredients of air, making up 99 per
cent, but that extra 1 per cent is still
really important. It’s like a glass of
wine: most of the wine is alcohol and
water, but there are all these extra
overtones and flavours, too. In air,
this 1 per cent is responsible for all of
global warming as well as all scents
and perfumes. It includes carbon
dioxide, nitrous oxide (laughing gas),
assorted pollutants and volcano
exhaust.
The ingredients of air reveal the
world’s entire history. Some of them
have been around since the early days
of the planet, while some only arose
with the arrival of life, or with human
civilisation.Where did our atmosphere
come from?
We’ve actually had four different
atmospheres in the Earth’s history.
The first was a wispy leftover from
our planet’s formation, and soon got
blown away. The next came from
the ground, seeping out of cracks in
the Earth’s surface – mostly carbon
dioxide and water vapour, but also
gases such as sulphur dioxide and
hydrogen sulphide. Atmosphere
number three was dominated by
nitrogen, emitted from volcanic vents in
relatively small quantities, but capable
of sticking around for a long time.
And finally, oxygen began to build up
in the atmosphere thanks to early,
photosynthesising life forms. This paved
the way for an oxygen-rich atmosphere
that could support complex life.CAESAR’S LAST
BREATH
BY SAM KEAN
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