Compared to the bony plates of an armadillo or the hard scales of a pangolin or even the
tough, leathery skin of an Indian elephant, the thin layer of delicate epidermis that
makes up our outermost covering may seem like pretty wimpy protection from the outside world.
Except, all we have to do is take a closer look at a our silky-smooth skin to see that
it actually IS a small patch of scaly armor. Those scales are made out of the same hard
protein, called keratin, as the scales of pangolins and other animals. Of course, ours
are a lot thinner, and therefore more fragile, but that isn’t normally a problem, because
we don’t regularly need to survive this. Our scales also don’t have to be super durable
because our body produces a brand new layer, composed of tens of millions of individual
scales, every day.
The giant, never-ending task of producing this armor is carried out by an equally giant
and never-ending army of skin cells in the underlying epidermis. Every second, some 500
new cells split off from stem cells at the base of the epidermis and join this army,
gradually migrating to the surface of your skin as younger cells form beneath and push
The journey to the top is one of ultimate sacrifice: In order to form a protective barrier
between you and the world, each cell is programmed to systematically destroy itself as it nears
the skin’s surface, using enzymes to dismantle its vital parts and essentially converting
into a hard, flat shield. In the process, it attaches itself to surrounding cells via
whisker-like预测和packets releases fill to the fat软性of spaces between一条。
whisker-like projections and releases packets of soft fat to fill the spaces between cells.
The outermost layer of your skin consists of about 15 sheets of this scaly mesh — as
thick as a piece of plastic wrap. Your flexible body armor forms a waterproof and surprisingly
effective barrier against penetration by bacteria, fungi, viruses, and other unfriendly interlopers,
while the acidic nature of the fats prevents similar nasty microbes from setting up shop
on your skin’s surface.
Of course, while our skin does a great job of protecting us from microscopic threats,
it is our brain, not our skin, that does the job of a pangolin’s scales – helping us avoid
getting eaten by lions.