Jaws of note
Question: I notice that when I thrust my jaw forward, so that my bottom front
teeth move out past the top ones, I hear a high pitched noise in both ears. The
noise persists as long as my teeth are sticking out. Assuming this is a common
experience, what causes it?
Answer: The noise is not real, but is actually 鈥渋nduced tinnitus鈥濃�攁
ringing or whistling caused by stimulation of the cochlea cells in the ear.
Your jaw is attached to your skull at the temperomandibular joint (TMJ). When
you force your jaw into extreme positions, the TMJ nudges the ear canal or
squeezes it slightly. This stimulates the cochlea, sending a phantom signal to
the brain. The signal is registered as a high-pitched whistle, or in some cases
as white noise, identical to the type of sound heard by tinnitus sufferers. You
may notice this ringing when you yawn. The ringing stops if you release the
pressure by relaxing your jaw. Some people have TMJ surgery to try to lessen
permanent tinnitus.
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You鈥檙e unlikely to trigger permanent tinnitus by pushing your jaw forward
like this, but if you did you would find the experience terribly distressing, so
don鈥檛 try it too often. There is no cure for tinnitus, and some people have
killed themselves because the sound has been unbearably loud. Once experienced,
tinnitus is never forgotten.
L. Prior
Devon
Bee lines 2
Question: Instead of foraging randomly for nectar, bees tend to stay with the
same species during a collecting session. The plants benefit from this by being
pollinated鈥攂ut what鈥檚 in it for the bees?
Answer: Honeybee foragers normally visit only one species of plant when
foraging because this helps them gather nectar more efficiently. Flowers
typically occur in patches so the same type are close together anyway. But each
species of flower has a different shape so must be worked in a distinct way.
Forager bees have to learn how to work each flower, learning where to put
their tongues to extract the nectar. If bees had to shift constantly from one
type to another they would be slower at handling each flower.
In the honeybee, specialisation is also a consequence of their waggle dance,
which hive-mates use to tell each other where plentiful patches of flowers are
located. This means an individual forager doesn鈥檛 have to spend time prospecting
for other flower species while she is foraging. Instead, she can focus solely on
her patch of flowers. When these flowers stop blooming, she either scouts out a
new patch herself or, more likely, is directed to a patch by reading waggle
dances back in the hive.
Bumblebees, on the other hand, have no communication system. Foragers must
constantly sample different species of flowers so they don鈥檛 miss the most
profitable species.
Francis Ratnieks
Laboratory of Apiculture and Social Insects
Sheffield University
Sociable junkie
Question: Is the Internet addictive? My mother always seems to be online
chatting with her friends. If it is, does this mean that you can actually become
addicted to your social life?
Answer: This depends on your definition of addiction. In the narrow sense of
physical dependence on a psychoactive chemical, the answer is not really. But in
the sense of mental dependence on an activity, the answer is yes鈥攐ne could
argue that it is reasonable to call it an addiction, obsession or compulsion.
However, it would debase the term to apply it to everyone who happens to enjoy
an activity and indulge in it whenever possible.
In the case of obsessive long-distance runners who run for the sake of a
鈥減ain high鈥�, for example, one could argue that there is a physical addiction to
internal opioids. Similarly, some obsessive behaviour may have physiological
components, but it seems more likely that when you鈥檙e overloaded with the
troubles and stresses of the real world, online correspondence takes your mind
off them, and can sometimes gain you a very satisfying circle of friends. You
soon associate that reward with the activity, and the need for it can rapidly
grow to the point where deprivation can be very distressing. Such compulsive
escape from unwelcome realities amounts to addiction of a sort.
But you mustn鈥檛 jump to facile conclusions about your nearest and dearest.
What you perceive as addiction may for them be a healthy and constructive social
activity. Their friendship could even be saving someone else鈥檚 life online. It
has been known to happen.
Jon Richfield
Somerset West, South Africa
This week鈥檚 questions
Bags of sleep: Why do dark circles appear under your eyes when you are
tired?
Tammy-Ann Sharp
New Romney, Kent
Bad credit 1: The Last Word has already told us why wiping dust off
malfunctioning credit cards helps them to work, but a colleague showed me that
covering a failing card in plastic wrap or cling film also makes it work again.
Why?
Dan
Auburn, California
Bad credit 2: Transparent tape stuck over the magnetic strip area also works?
Why?
Leon Le Leu
Deakin West, ACT
Wave front: My son is dismayed to have inherited my hair 鈥渟tyle鈥�. We both
have mainly straight hair, but there is a single, pronounced wave towards the
front. As new hair grows, it starts off completely straight and then, at the
2-centimetre mark, suddenly kinks. How does the hair know how to do this, and
how can the trait be inherited?
Gill Mulley
Southampton, Hampshire
Geiger prawns: I recently read an article about illegally irradiated food.
Tests showed that frozen supermarket prawns had been subject to this process.
How is it possible to test a prawn for previous exposure to gamma radiation?
John Bowes
Newton Aycliffe, Durham
Travel tips: Why are the wing tips on modern passenger jets upturned?
Zert
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