India, Nov. 15 -- It is one of the world's oldest cosmetics. For thousands of years, people have tinted their lips as part of a beauty regimen. In Ancient Egypt, such mixes were made with henna, crushed ants and natural dyes. Today's "kiss-proof" variants really do stay on for hours.

Before we dive into the massive global lipstick industry (worth an estimated $17.4 billion in 2024), let's take a closer look at the features they were made for: the lips themselves.

Human lips are extraordinary in both form and function. They help us eat, speak and express emotion. They form a seal for sucking, which is vital for breastfeeding infants. Packed with thousands of nerve endings, they are among the body's most sensitive areas, helping us detect...