I came across the phrases 'crow's feet' and 'worry lines' several times. Please enlighten me about the origin of these two phrases and the difference between them.
According to the Random House Dictionary, crow's feet originated sometime between 1350–1400. The phrase refers to wrinkles on the outer corner of the eye, like a crow's foot or footprint, as opposed to worry lines--wrinkles on the forehead.
The most commonly used definition of crow's feet is “tiny wrinkles at the outer corner of the eyes, resulting from age or constant squinting” and are so called because of the likeness to a crow’s foot or footprint. It originates in the late 14th century from Middle English and is believed to have first appeared in print in Chaucer’s poem “Troilus and Criseyde.” The phrase in the singular is crow’s-foot, but it is most often used in the plural, as in crow’s-feet.
It can also mean “an embroidery stitch with three points, used as a finish at the end of a seam or opening,” or “an arrangement of ropes in which one main rope exerts pull at several points simultaneously through a group of smaller ropes, as in balloon or airship rigging.” These other definitions are much less frequently used, and when they are, it is usually in the singular crow’s-foot.
Worry lines : a crease or wrinkle on the forehead or between the eyebrows, (while crow's feet develop at the outer corners of the eyes)
This expression has been used since the beginning of last century but has become popular since the 60's probably with the development of the beauty industry.
To supplement @Sel and Josh61's answers.
For some reason, the highly unflattery term, crow's feet are wrinkles normally associated with women. The tiny fan-like lines at the outer corners of eyes occur over time when a person repeatedly squints or laughs, in fact a more complimentary term to describe the marked lines on someone's face would be laughter lines or character lines.
On the other hand, worry lines are caused by the repeated raising of eyebrows which in turn lead to the furrowing of the forehead, they are said to represent the expressions of worry and concern. The term is used indifferently between men and women and according to Merriam & Webster it was first used in 1972.
One of the first written instances of worry lines I found online which contradicts with the M&W claim is in the book titled: Are We All Deceivers?: The Lover's Blue Book (1896)