The New York Times article from which I got this information says, “hair sits at the boundary between biology and identity.” Also: It serves as a “sensor for your brain and an archive of your body’s secrets.” Goodness! Really? Here’s the explanation:
Hair is made mostly of keratin, a tough protein also found
in your nails. You have about 100,000 hair follicles on your scalp and many more
across your body. Each follicle cranks out the strands as well as the pigment
that gives it color. Bacteria, viruses and fungi live within the follicles—a
microbiome that keeps out harmful germs, reduces the risk of infections, and helps
your hair grow. Your hair follicles also help heal wounds by sending stem cells
to the wound where they create new skin cells.
As for your brain, your hair acts like motion detectors. Because
the follicles are wrapped in nerve endings that fire at the slightest touch, if
an insect drifts near your eyes, for example, your lashes sense it and you
blink. The nerves also feed into your brain’s emotion centers, which is why a
gentle caress can feel pleasant. In addition, hair follicles contain smell and
bitter-taste receptors that influence hair growth. Some research indicates that
certain fragrances seem to stimulate hair growth while others might inhibit it.
Like your brain, the follicles also have an internal clock with a resting and
shedding cycle. (Hair grows faster in the morning than in the evening.)
As the second-fastest growing tissue in the body—after bone
marrow—hair serves as an archive of your health, signaling when something’s
wrong. Follicles suck up toxic compounds and deposit them in your dead hair
shaft. A centimeter of your hair captures a month’s worth of biological data:
drug use, poisons, chronic stress, and even medication adherence.
Because keeping the pace of growth takes a lot of energy,
rapid hair loss can serve as a sign of illness or stress. Of course, some hair
shedding is inevitable—we lose about 50 to 100 strands of hair each day.
The article didn’t explain what happens when you lose a lot
of hair in old age. Inquiring minds want to know!
For an introduction to this blog, see I Just Say No; for a list of blog topics, click the Topics tab.
ReplyDeleteReally interesting. The part that touched me deeply was the awareness that a gently touching or patting (on your head) generates such a good feeling. I just tried gently rubbing my hair and I agree, it really does feel very pleasant.