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PHOTOS: NASA, SCIENCE PHOTO LIBRARY, ISTOCK ILLUSTRATOR: SAM FALCONER
One hypothesis is that the iron sulphide
spewing from deep-sea volcanic vents
precipitated into a solid mass with lots
of tiny chambers where simple biological
molecules could become concentrated and
assemble, using energy from iron redox
reactions. The ‘panspermia hypothesis’, on
the other hand, suggests that living cells
or spores may have arrived fully formedHow did life on Earth begin?
NO EASY ANSWERtravelling on comets from outer space.
Recent research by Prof John Sutherland
at Cambridge University offers a possible
compromise between the two: comet
impacts may have delivered hydrogen
cyanide, which reacted with the hydrogen
sulphide already on Earth to form the
earliest building block molecules. That then
assembled to form RNA. LVOur brains have obviously evolved to work
in Earth’s gravity. Experiments on the
International Space Station suggest that
our brains have an internal model of how
gravity works that we use to accurately
predict where a ball will be when we move
to catch it. In a weightless environment,
the ball moves at a constant speed,
instead of a constant acceleration, and
so our reactions are slightly off. Gravity
also affects the flow of blood through
the brain; at accelerations beyond 5g,
this begins to affect the brain’s electrical
activity, producing patterns that resemble
epileptic seizures. LVHow does
gravity affect
brain function?
Just don’t come crying to us
when you find a rogue
grapefruit clogging up some
vital equipmentDid life on Earth start at
hydrothermal vents, or did it
arrive on a comet?