Why Do Humans Have Eyelashes?

The eyes are the windows to the soul, as the old saying goes, and a major component of those eyes is the eyelashes. The importance of these few follicles that rim our eyelids--at least in contemporary culture--is difficult to understate. The mascara industry, whose sole purpose is to accentuate the eyelashes, generates more than $5 billion each year as of July 2009. Beyond simply enhancing physical appearance, however, the eyelashes play an important part in maintaining the health of the human eye.

Function

• The primary biological purpose for eyelashes in humans, and other mammals for that matter, is to protect the sensitive eyeball from dirt and debris. Blinking the eyes not only spreads natural lubricants (in the form of tears) over the surface of the eye, but it allows the eyelashes to filter out small dust and dirt particles that can scratch and irritate the eye.

Considerations

• A secondary purpose of the eyelashes has to do with sexual attraction. Like eye contact, widening of the eyes, dilation of the pupils and "sparkling" of the eyes caused by increased tear production, fluttering of the eyelashes is an indicator of heightened sexual awareness or interest.

Effects

• Eyelashes are sensitive to the touch. When a foreign object, such as a bit of dust or a flying insect, brushes against the eyelash, the eyelid will close reflexively to protect the eye from damage.

Warning

• Certain conditions can affect the ability of the body to grow or maintain healthy eyelashes. Diseases of the eye like hypotrichosis or alopecia; allergies and allergic reactions to drugs or chemicals; and even common household toxins may cause they eyelashes to become weak, break or fail to grow back. Because eyelashes serve an important physiological purpose beyond their cosmetic role, a person suffering from a loss of eyelashes should seek medical care

New Developments

• While the false eyelash market is robust, a product has received approval from the U.S. Food and Drug Administration (FDA) for the treatment of insufficient eyelashes. Latisse, the brand name for Allergan's prescription drug, belongs to a category known as prostaglandin analogs. While these products are known to effect longer and fuller eyelashes, they are also quite expensive as of July 2009. They may also result in red, itchy eyes and changes in eyelid pigmentation, and may even change the color of the iris.