54 | New Scientist | 13 July 2019
Clucking dinosaurs
When a Tyrannosaurus rex or other
carnivorous dinosaur is depicted on
screen, it roars like a carnivorous
mammal. But birds developed
from dinosaurs, so could they have
screeched or called like the modern
cassowary, or made no noise at all?Tony Holkham
Blaenffos, Pembrokeshire, UK
The same question occurred to me
when I first saw Jurassic Park. Why
would a stealth predator roar?
T. rex was a carnivore, and
carnivores are usually only vocal
when establishing territory or
seeking a mate. Advertising their
presence when hunting wouldn’t
be smart. The same goes for birds,
which evolved from dinosaurs.Mike Follows
Sutton Coldfield,
West Midlands, UK
There is no way to be sure what
T. rex sounded like because the
soft tissues of its voice box
haven’t been fossilised.
The roar of the T. rex in Jurassic
Park was created by combining
sounds made by a baby elephant,
alligator and tiger. But dinosaurs
would have used sound not to
frighten prey but to communicate.
Birds and crocodilians are the
dinosaurs’ nearest living relatives.
Julia Clarke at the University of
Texas has combined the booming
cry of the Eurasian bittern
(Botaurus stellaris) with sounds
made by Chinese alligators
(Alligator sinensis) to make a
fearsome low-frequency rumble
ideal for long-distance calling.
The fossilised ear cavities of T. rex
suggest they were sensitive to
low-frequency sound.
Or maybe dinosaurs didn’t have
vocal organs and made vibrations
in resonating chambers. This
would have allowed them to make
noises with their mouths closed,
as birds and reptiles do.Peter Jones
Wolfenbüttel, Germany
Those interested should check out
the “Jurassic Squawk” episode ofBBC Radio 4 series The Curious
Cases of Rutherford & Fry, from
May 2019. T. rex may not have
had a larynx or had a mouth
cavity suitable for vocalisation. Its
branch of dinosaurs evolved into
birds, which use a different organ,
the syrinx, to make sounds, but
this developed later. Our best
guess, based on closed-mouth
vocalisation similar to modern
crocodiles, is that they made an
underwhelming low-pitched hum.
If you turn the volume up, it does
sound a bit more threatening.Richard Lucas
Camberley, Surrey, UK
The only dinosaur sound we have
any confidence in is that of the
Parasaurolophus. Its bony, crested
skull held tubes connected to its
nasal passages that would have
been used to make a sound like
a trombone. Birds use a thoracic
organ called a syrinx to form their
calls. A late-age dinosaur fossil
complete with syrinx has recently
been found in Antarctica.Hazera Forth
Bedford, UK
This is why my 10-year-old and
I cluck when a T. rex appears in
any scene of the Jurassic Park
franchise. It is hilarious.Foam over
When I drain a can of chickpeas,
the liquid forms a soapy foam.
What causes this, and if it is
related to soap, could it be used
as an eco-friendly replacement?Isabella Van Damme
Arborfield, Berkshire, UK
The foaming ability of chickpea
water, often referred to as
aquafaba, makes it a suitable
vegan replacement for egg white.
Proteins and other compounds
seep out of the chickpeas duringcooking. Aquafaba’s foaming
capacity correlates with the
water’s protein content. Proteins
can stabilise air bubbles in foam
by forming a film over them, as
happens with whipped egg whites
and milk foams. The proteins also
impart gelling properties and
stabilise oil-water emulsions.
And the liquid contains
saponins, another group of
compounds able to stabilise
bubbles. The cooking water of all
pulses shows these properties to
some extent, but chickpea water
appears to be one of the best and
has a range of applications in food.David Muir
Edinburgh, UK
Many plant materials contain
long molecules such as lipids,
proteins and carbohydrates,
which may behave as surfactants,
or surface-active agents. These
lower the surface tension of
water and can act as emulsifiers
and foaming agents. Soap and
detergent are also surfactants.
The viscous liquid left
after beans and peas have been
cooked, as well as in tins of such
legumes, is called aquafaba, which
translates as bean-water. It can be
used as an eco-friendly handwash,
since it probably ends up going
down the drain anyway. As a vegan
replacement for egg whites, it can
be used to make foods like ice
cream and marshmallows.Don Taylor
Sydney, Australia
Aquafaba can be used to make
meringues. It may also be used
in other dishes that require
egg whites, such as fettucine
carbonara. Egg replacement
would be at the rate of
60 millilitres to 1 egg. ❚This week’s new questions
Far-sighted On a safari holiday in Kenya, I was stunned
by our local guide’s ability to see wildlife at a great distance
and spot things that I could barely see with binoculars. Does
visual acuity vary between human peoples? John Wilkinson,
Diss, Norfolk, UKFood fatigue I often feel tired after a large meal and I am
told it is because blood “rushes to the stomach to help with
digestion”. Is this actually what happens? How can the body
regulate that? Evan Slater, London, UKWant to send us a question or answer?
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DEEP
OLBYPLAINPICTUREDo some human peoples
have better eyesight
than others?