New Scientist - USA (2022-04-09)

9 April 2022 | New Scientist | 55

Answers

Quick quiz #146

Answers

1 Altricial

2 Small solar system body,

defined as objects that aren’t

planets, dwarf planets or

natural satellites

3 Antonie van Leeuwenhoek

4 12

5 Lichen

Cryptic Crossword

#80 Answers

ACROSS 1 Edmond Halley,

9  Taffeta, 10 Ionic, 11 Xenobots,

12 Psst, 14 Meteor, 15 Season,

18 Odds, 20 DeepMind,

23  Slake, 24 Gyrated,

25  Transcendent

DOWN 2 Defunct, 3 Open book,

4  Dearth, 5 Aril, 6 Lends,

7  Yucatan, 8 Styx, 13 Tempered,

14 Moonset, 16 Stilton,

17  Beagle, 19 Drama,

21  Dodo,  22 Cels

#161 Reduction

deduction

Solution

Lionel’s birthday is 25 May.

365 is a product of two prime

numbers: 5 and 73. So every fifth

day and every 73rd day would

result in a reducible fraction if we

write them as day of year/365.

There are two points in the year on

which two consecutive dates given

as fractions are reducible. These

are the 145th and 146th days

(reducible to 29/73 and 2/5),

and the 219th and 220th days

(reducible to 3/5 and 44/73).

In the first pair, the second day

contains the smaller numbers,

so that must be the correct pair,

and thus Lionel’s birthday is on

the 145th day, or 25 May.

Tom Gauld

for New Scientist

and disease to maintain this level.
Fertile land, like most of
Europe, might support one
hunter-gatherer per 26 square
kilometres, but this falls to as
low as one per 250 km2 in the
Australian desert, as calculated
by Ian Simmons in his book
Changing the Face of the Earth.
The World Bank estimates
that 37 per cent of Earth can
be classed as agricultural land,
but through forest clearance,
agriculture has probably been
responsible for some degradation
and desertification of formerly
fertile lands. So let’s say that, in
a pre-scientific age, 50 per cent
of Earth’s 500-million-km2 land
area (minus Antarctica) would
be “fertile”. Using Simmons’s
figures, we then have a non-
agricultural population of
around 10 million people.

Mike Follows
Sutton Coldfield,
West Midlands, UK
The short answer is about
10 million. Growing crops
increases the population

that can be sustained by

the same area of land. This is

why the earliest civilisations

developed alongside major

rivers, where the water could

also be used to irrigate the ground.

This led to a population explosion

to maybe 50 million people,

concentrated in Mesopotamia,

ancient Egypt and the Indus valley.

Agriculture has increased the

proportion of biomass that is

edible. This has been enhanced by

the use of insecticides, herbicides

and artificial fertiliser. Yields have

also been enhanced by plant and

animal breeding, and factory farms

increase them still further. The

land available for farming has

been expanded by irrigating

deserts and draining swamps.

But the population increase

to nearly 8 billion wouldn’t have

been possible without the

economic systems and transport

infrastructure that allows food

to be moved from place to place.

Imagine if agriculture were

uninvented and we had to draw

lots to decide who would inhabit

this new world. Each of us would

have odds of about 1 in 800. Given

that we are bending nature to our

will to extract 800 times as much

food as it would yield naturally,

we surely have a responsibility

not to waste what we produce.

Peter Sutton

Guildford, Surrey, UK

The most likely answer is

something between 2 million

and 20 million, as without

agriculture, we would be restricted

to a semi-nomadic lifestyle.

What is certain is that in such

a world, with no domesticated

livestock, there would be millions

more elephants and hundreds of

thousands more lions, tigers and

whales. This would be fantastic.

However, it is most unlikely

that we would be reading about

it in New Scientist.  ❚

“ Imagine if agriculture

were uninvented and

we had to draw lots to

inhabit this new world.

We would have odds

of about 1 in 800”