6 March 2021 | New Scientist | 55Tom Gauld
for New Scientist
Answers
Quick quiz #91
Answers1 Lithium-ion battery
2 Bubonic, pneumonic, septicemic
3 Flying fish
4 Glenn was 77 when he flew
on space shuttle Discovery’s
STS-95 mission in 1998
5 ZincQuick Crossword
#77 AnswersACROSS 1 Shipbuilding,
10 Neptune, 11 Chiasma,
12 Y-axis, 13 Gene chip,
15 Tear glands, 16 Plan, 18 Toes,
20 If you ask me, 22 Ontogeny,
24 Alula, 26 Ehrlich, 27 Tool kit,
28 Chess problemDOWN 2 Hypoxia, 3 Plus sign,
4 Uvea, 5 Locked door, 6 Imide,
7 Gasohol, 8 And yet it moves,
9 Carpenter ants, 14 Half-inches,
17 Catacomb, 19 Enteric,
21 Knuckle, 23 Glide, 25 Star#102 Passport
to success^
SolutionThe passport number is- Since AB is
divisible by 2, B must be even,
and by similar reasoning so
must D, F and H.
Since ABCDE is divisible by 5, E
must be 5, meaning A, C, G and I
must be 1, 3, 7and 9 in some
order. ABCD is divisible by 4, so
CD is also divisible by 4, meaning
CD must be one of 12, 16, 32,
36, 72, 76, 92 or 96. This
means that D can only be 2 or 6.Similar reasoning narrows
down which digit can go where,
ending with the unique answer.
381654729 is the only
pandigital (i.e. uses all the digits
once) polydivisible number.Bird banter
Many birds are able to remember
and mimic sequences of sounds
they hear, including human speech.
What evolutionary advantage does
this skill give them?
Mike Follows
Sutton Coldfield,
West Midlands, UK
The evolution of the advanced
ability to mimic the birdsong of
other species, and even sounds
heard in the environment, is
usually driven by sexual selection.
Female superb lyrebirds, for
instance, are more attracted to
male lyrebirds that have a more
sophisticated repertoire of songs
and sounds. This is probably
because this ability signals
greater biological fitness,
which increases the likelihood
that their offspring will survive.
New research also shows that
male superb lyrebirds imitate
alarm calls of a “mobbing flock”
while mating. And captive
lyrebirds have been observed
mimicking the camera shutters
of picture-taking visitors and
the sound of chainsaws on
a nearby construction site.
Perhaps learning to mimic
a more diverse range of sounds
requires more intelligence and
this might translate into an
ability to find scarce food or
evade predation.
Flocks of greater racket-tailed
drongo often share the same trees
as other bird species. By imitating
raptor calls, the drongos can
induce the other birds to take
flight and abandon their food
to them. They then hop over
and steal it. So being described
as a drongo isn’t quite as insulting
as intended.
Some species of bird, such as the
grey parrot, only exhibit obvious
sound mimicry when in captivity.
Grey parrots are social birds thatcommunicate important
information with their flock-
mates. In the absence of a flock,
they vocalise with other species
or their human companions.
Perhaps they derive intellectual
satisfaction from parroting
their owners?Seeing small
What is the smallest animal with
eyes and could it see a molecule?
(continued)?Eric Kvaalen
Les Essarts-le-Roi, France
I think it is possible for us
humans to see a single molecule.
There is a technique in which
single molecules are tagged
with fluorescent labels, then
a microscope is used to see
whether different molecules
occur in the same place.
If the illuminating light is
strong enough, I suppose it
would be possible to see a dot
of fluorescence at the location
of one of the labelled molecules,
even without a microscope. ❚“ Greater racket-tailed
drongos imitate raptor
calls, inducing other
birds to take flight
and abandon their
food to them”