BBC Science Focus - 03.2020

Q&A

GET T Y IMAGES X3, NIGEL SWALES ILLUSTRATIONS: DAN BRIGHT

JIMMYPHILLIPS, BRISTOL

WHAT’STHE TALLEST MOUNTAIN IN

THE SOLAR SYSTEM?

YOUCAN CURE YOUR

HICCUPS BY DRINKING

FROM THE WRONG

SIDE OF A GLASS

OLDWIVES’

TALES...

Hiccupsare involuntary contractions of
the diaphragm. These contractions cause
a sudden inrush of air, slamming shut the
leaf-shaped flap of cartilage in your throat
known as the ‘epiglottis’ (this is what
causes the ‘hic’ sound).
The documented cures for hiccups
generally fall into three categories –
raising the level of CO 2 in your
bloodstream (holding your breath),
stimulating the vagus nerve (sticking your
finger in your ear – or anus!), and
distraction (a sudden fright). The
technique of drinking from the wrong side
of the glass may be a combination of the
last two: it requires you to concentrate on
the task, and cold drinks stimulate the
vagus nerve through the stomach wall. If
you drink a large glass without stopping,
you may even interrupt your breathing
for long enough to affect your blood CO 2
levelstoo.
However, none of the folk cures for
hiccups have good scientific research to
back them up, and scientists don’t
understand the mechanisms that might
be at work. Most studies are anecdotal
reports of cures for patients with
persistent bouts of ‘intractable hiccups’
that have gone on for months or even
years, and it’s possible that these have a
different underlying cause. For more
ordinary episodes of hiccups, there seems
to be a large placebo effect at work – so as
long as you believe in the cure, it will
probably work.LV

Leaving aside the obvious answer that humans

often deliberately introduce fish to lakes and

ponds, we can draw a comparison with the

population of isolated islands. Just as an island

may once have been connected by a land

bridge, so lakes may originally have been part

of river systems that dried up. Or a river may

have flooded long ago and briefly flowed into

low-lying land to create a populated lake.

Some lake residents are even descended from

ancestors that crossed from one lake to

another. While most fish can’t travel very far

over the land, their eggs will survive for several

hours out of water. When waterbirds come to

lakes to feed, fish eggs might get stuck to their

feathers, hitching a ride to a new home.LV

Olympus Mons, an extinct volcano on Mars, is

often quoted as the highest mountain in the

Solar System, at a height of 21.9km (two and a

half times the height of Everest). However, the

mountain peak in the centre of the Rheasilvia

crater on the asteroid Vesta, at about 22.5km,

appears to be marginally taller. We don’t

know for sure because of difficulties in

defining the mountains’ ‘base’ heights, and

uncertainties in measurements.AGu

AMY-GRACE ENZER

HOW DO FISH END UP IN ISOLATED BODIES OF

WATER LIKE LAKES?

OlympusMons,

illustrated here, is

an extinct volcano

on Mars