Animals need to know where they are
going, so they must have eyes that look
forwards. If they also had eyes on the backs
of their heads, the brain would have to
combine these two totally different views
into one, including opposite directions of
movement. A simpler solution, found in many
prey animals, is to have eyes on the sides
of the head to give a very wide field of view.
Rabbits, for instance, have eyes high up on
the side of the head. The disadvantage is a
small blind spot right in front of them. Goats,
however, have horizontal pupils that allow
them to see 320° with no blind spot. SBWhy don’t prey
animals have eyes
in the backs of their
heads?
When will Earth become
uninhabitable?
Over the centuries there have been
many attempts to predict the death of
our planet. Even Isaac Newton tried,
allegedly predicting the end of the world
in 2060.
But the idea that we’ve got until the
Sun runs out of nuclear fuel over five
billion years from now is also a myth.
According to astronomers, the Sun is
destined to turn into a huge, glowing red
giant star, potentially engulfing the Earth
in the process. But long before that, the
extra heat striking our planet will trigger
the evaporation of sea water. That will
drive up atmospheric levels of watervapour – a far more potent source of
global warming even than CO^2. And that,
in turn, will make the Earth even hotter,
leading to catastrophic ‘runaway’ heating
that eventually evaporates the oceans.
Simple computer models initially
suggested this disaster could render
our planet inhospitable in as little as
150 million years from now. But late
last year the journal Nature published a
much more sophisticated simulation by
a team from the Laboratory for Dynamic
Meteorology in Paris, and this suggests
we have got at least a billion years before
this apocalypse. RMWould a tardigrade
survive passage
through your gut?
The goat’s horizontal pupils let it see to the side and fronthowever, have horizontal pupils that allow
them to see 320° with no blind spot.SBLife on Earth could
meet its demise
long before the Sun
becomes a red giantPHOTO: SCIENCE PHOTO LIBRARY X2, ALAMY X2, GETTY
This tough little
tardigrade isn’t fazed
by much - even an acid
bath in your stomach&
These microscopic animals have a well-
deserved reputation for extreme toughness.
To protect themselves they can transform
into a barrel-shaped cyst called a ‘tun’. In
this state they can survive temperatures
as high as 151ºC or as low as –272ºC and
very long periods without air or water. Their
resistance to acid is less well documented,
but a 2005 study at Columbus State
University found that they were unaffected
down to at least pH 3, which is almost as
acidic as your stomach. Assuming they
survived that, the trip through your intestines
would be a breeze. LV