Full, rosy lips are associated with high levels of estrogen, which decreases with age, meaning that lips become thinner and paler as you get older. And this is why lip gloss was invented. Playing up the pinkness is a way to scientifically appear more youthful. Other surefire signs of health and youthfulness include thick hair and eyebrows, and skin with a dewy glow. (Fortunately, there’s dry shampoo, brow pencil and face oil when you need an extra kick of those.)

READ MORE: Play Up Your Sexy Features With Science