BBC_Knowledge_2014-06_Asia_100p

We humans like to

spread ourselves out -

more so than any other

animal on Earth

Which species collectively takes up the most space?

The further up the food chain an

organism is, the larger each individual

tends to be, but the smaller the total

weight for the whole species. That’s

because not all the food an animal eats

is turned into body mass; some is used

to drive the metabolism. Blue whales, for

example, weigh about 150 tonnes each

but there are only about 10,000 of them so

their total weight is only about 1.5 million

tonnes. The Atlantic krill that they eat are

just a few centimetres long but collectively

they weigh more than a hundred times as

much as the total mass of blue whales.

The plankton that the krill eat probably

outweigh them by a similar margin, but

they comprise lots of different species

so the ‘per species’ weight is lower.

But if you consider the space that a

species takes up, rather than its simple

biomass, it’s possible that humans

would rank top. Around 0.5 per cent of the

total land area on Earth is urban land and

while other species share that land with

us, the biodiversity in cities is much lower

than in the countryside. When we build a

city, we claim that space for ourselves

and keep other animals out much

more effectively than other animals do

with their own territories. Half the world’s

population lives in towns and cities now,

so the 750,000km2 of urban land equates

to 214m^2 per person. This means a city

dweller takes up about twice as much

space as a blue whale. And there are

350,000 times more of us. LV

Are growing pains medically recognised?

Yes, but only as what is called a
‘diagnosis of exclusion’. In other words,
if a child complains of recurring leg pain
at night and no medical condition is
found, a doctor may blame ‘growing
pains’. About one in four children
experience them, often when aged three
to five, or eight to 12. The pain comes

in both legs in the evening or during the

night, often after a particularly active day,

and can be in the thighs, calves, or shins

but not in joints.

Since there’s no good evidence linking

the pains to growth, some experts prefer

to call them ‘recurrent nocturnal limb pain’

or ‘benign leg ache in children’. SB It’s no pain no gain for one in four children