Probably the most popular bealife about the cause of wrinkles is to blame them on a protein deficiency.
There is one theory that states that old people get wrinkles because they have weaker acid in the stomach, which diminishes their ability to break down protein into amino acids, and because of this they run out of protein necessarily to repair the skin.
The other common misconception about wrinkles is that if you eat collagen containing foods or take collagen supplements somehow that collagen is going to go to your skin and make it more elastic, preventing wrinkles and sagging skin.
Well this two theories are dead wrong, wrinkles are a biomechanical problem not a deficiency one.
You can do a little observational experiment, and pay attention to the people around you. It is very likely that you are going to observe the fallowing relationship, the people who have the worst posture also have the most amount of wrinkles and sagging skin, while the people who have good posture even if they are older don't have to many wrinkles or sagging skin.
The more deformed your spine is going to be, the more deformed the rest of the body is also going to be including your face. When you start correcting the posture you are also going to notice the skin on your body tighten and normalize.
Think of it like this, the skin is attached to the muscles. If the muscle becomes tight and shortens the skin on top of the muscle is going to buckle and crease.
And if the muscle doesn't have enough tension in it is going to fall under the force of gravity and hang loose, and the skin with it.
Generally people get wrinkles and sagging skin in a similar pattern. They get to much tension around their forehead and eyes, and everything underneath, like the check bones, corners of the mouth, jaw line and front of the neck sag.
This happens because of the reverse curve in the neck most people have. Under normal circumstances your neck should be curved backwards, this will create the tendency for your head to fall back.
In order to prevent it from falling you would have to engage the muscles in the front of your neck, for as long as you are vertical the front of your neck should be under constant tension to prevent your head from falling back.
But if you have a reversed curve in the neck, or if your neck curves forward and your head hangs in front of your shoulders. You now have to hold your head up with the muscles in the back of your neck, in order to prevent it from falling forward.
The entire chain of muscles that starts from the back of your shoulders continues over the back of the neck, over your skull, forehead and around your eyes is going to work harder than it should and become tight.
And the muscles underneath, that should actually stabilise your head, atrophy, stretch and start to sag.
Which is why not only people get wrinkles, but all of them get them in a similar way!