While lower levels of collagen, increased inflammation, and a decrease in hydration-enhancing molecules in the skin all contribute to aging, there's one other factor that might surprise you. You know that sun isn't great for your skin, but as it turns out, it's really not great for your skin. Shockingly, skin that had not been exposed to the sun had around 3,000 genetic mutations, but skin with exposure had — are you ready for this? — nearly 10,000 genetic mutations. So if that's not another reason for you to run and grab the sunscreen, I don't know what is.