You probably don’t need an explanation as to how the
injury pictured above happens. And you probably don’t need to be told how
much they hurt — so, so much, especially given the relatively tiny injury
to a body part which is generally rather hardy. So, let’s talk
about why this
happens.
First, why do we get paper cuts in the first place? How
can a sheet of paper slice our skin in a way that a much sharper,
otherwise more dangerous item never could? The short answer is that
the edges of paper are actually pretty sharp, even if the sheet as a
whole isn't. Rub your finger slowly over the edge next time you get a
chance (slowly!
don’t get a paper cut on my account!) and you’ll intuitively understand
the risk it entails. According to Wikipedia, when paper sheets
are “strongly fashioned together” — such as out of a fresh ream of paper
— they’re more likely to cause you harm, so caveat paper-user. (There
needs to be a good Latin word for that.)
The cause of the pain, though — that’s much less
straightforward. There are a few theories.
One potential culprit is the location of the injury. Our
hands (and in particular, our fingers) have a large number of nociceptors
— ABC News describes them as “the nerve
fibers that send touch and pain messages to our brain” — and a high
density of nociceptors to boot. The paper cut stimulates a lot of
nociceptors and therefore our brains get a disproportionately high
indicator of pain. And really, that’s what pain is — a message from our
brains telling us to freak out (and ideally, stop what we’re doing or get
help).
On top of that, the paper isn’t a smooth edge like a razor
blade is, as mental_floss observes. At a microscopic
level, paper’s edges are jagged and, therefore, act like a
teeny-tiny buzz saw through a field of pain receptors, making a
proportionally large number of similarly tiny cuts along the way. And
then there’s the question of the leave-behinds. Indiana Public Media’s “A Moment of Science” points
out that some of paper’s component parts are often left
behind within the cut (this isn’t true when talking about a metal razor
blade), and as the wound heals, these foreign objects jab and prod at the
injury from within.
To make matters worse, paper cuts rarely bleed very much,
because they’re so shallow and our skin in that area is generally thick.
The lack of blood means that there’s little opportunity for a blood clot
to form, protecting the wound. As we use the injured finger, there’s a
very large chance the cut will re-open, exposing the same nociceptors to
the air, and triggering the “ouch!” message once again.
But if it’s any solace, the next time you cut your finger,
you’ll be able to go through the theories as to why it hurt so much — a
few seconds after you’re done prattling off some expletives.
WHEN America’s unemployment was last as low as it has been recently, in
early 2007, wages were growing by about 3.5% a year. Today wage growth seems
stuck at about 2.5%. This puzzles economists. Some say the labour market is
less healthy than the jobless rate suggests; others point to weak productivity
growth or low inflation expectations. The latest idea is to blame retiring
baby-boomers.
The thinking goes as follows. The average worker
gains skills and seniority, and hence higher pay, over time. When he retires,
his high-paying job will vanish unless a similarly-seasoned worker is waiting
in the wings. A flurry of retirements could therefore put downward pressure on
average wages, however well the economy does. The first baby-boomers began to
hit retirement age around 2007, just as the financial crisis started. And since
2010, the first full year of the recovery, the number of middle-aged workers
has shrunk considerably. They have been replaced partly by lower-earning
youngsters Does ageing explain America’s disappointing wage growth?
|
