There are three types of hair on humans, based on
hair follicle size: lanugo (the hair that newborn
babies often have), vellus (the short,
fine,unpigmented hair on cheeks, necks, and
similar places), and terminal (the thicker,
pigmented hair on the head, eyebrows, eyelashes,
whiskers, limbs,and genitals).
to have (or keep) hair on our eyelids because it
helps keep sweat and foreign objects out of our
eyes, and reduces the risk of eye
For early humans to have evolved
this feature, it must have given them are
Eyelash hairs come
from the same type of follicles as the hair on
your head,and the hair shaft itself is very
Eyelashes are different than head
hair, though, in that they grow very slowly--about
a tenth of a millimeter per day. The reason why
their length appears to be constant (about
7.5millimeters) is that the ends break off with
the wear and tear of daily life.
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