Having covered paleo hair, let's move on to how to get great skin and keep it that way by using some simple biology. Clearly girls will benefit from this, but guys too will continue to enjoy solid mental health and a big fat smile on their face as long as they still get attention from young girls. And to point out the obvious, the men who adorn the walls and ceilings of nubile babes look more like Johnny Depp than Clint Eastwood.
Even if your genes don't predispose you to competing based on dreaminess, compare Berlusconi to other powerful men of the same age -- his skin looks like that of a man at least 20 years younger. The reason we find youthful looks attractive especially in middle or old age is that they are a signal of good genes. If you're 20 years old, male or female, you have to try to look repulsive. That's an easy task when you're 60, though. So if you've managed to prove how resistant you are to the aging process, even if you still don't look as youthful as you did in your 20s, everyone nevertheless infers that you've got some powerful set of genes to have pulled it off.
There is less error behind this inference than a similar inference of good genes based on good looks in a 20 year-old. Thus, risk-averse females will be even more receptive to sleeping with a dreamy, youthful looking 40 year-old than his 20 year-old counterpart. A sex-only relationship is a strategy to just get the guy's good genes. If she were trying to get greater parental investment, she'd go after someone with more control over resources. If she were after someone with shared interests and a desire to go steady, she'd pick someone closer to her own age. So you probably won't develop a sustained relationship with any young girl when you're in your 40s -- but it's a nice consolation prize to still get wildly fucked by them.
Moving onto what builds and maintains healthy skin, most of the story is vitamin A. Vitamins C and E also help, and of course you need to eat plenty of fat since most cells in your body are fat-dependent and because vitamins A and E are fat-soluble (they need to be taken with fat in order to be absorbed). But as long as you focus on vitamin A, you'll pretty much be set. You may already know that it's involved in vision, but its more important role is in the epithelial cells -- any cell on the "surface" of your body. That includes all of your skin but also the "inner surfaces" like the lining of your respiratory tract and digestive tract. Get low on vitamin A, and you're more likely to get a respiratory infection or to not properly digest your food and absorb its nutrients.
Not getting the flu is nice, and strengthening your skin will also help to keep out pathogens that would enter that way. But we don't live in an environment where measles, leprosy, etc., are rampant, so this probably won't persuade too many people to start getting enough vitamin A. Rather, do it because you won't have disgusting Jabba the Hut skin that, being hard to conceal, will tend to turn away all sorts of people who see you -- not just total strangers, but also love interests and potential allies. ("I don't know how trustworthy he is -- just look at how much he's let himself go.") Well into middle age, Cary Grant and Bryan Ferry still had firm, bouncy, glowing skin, and continued to date beautiful women decades younger than they were.
Where do you get vitamin A from? Only one place -- liver. That is where it is overwhelmingly stored. It is also stored in far smaller amounts in other animal fats, so dairy products and even the fat on muscle meat has some in it, but not that much at all. Vitamin A does not exist in any non-animal food, although the building blocks called caretinoids do. However, the conversion of these building blocks into the real deal is not free and perfectly efficient -- it takes a lot of the building blocks to make a single unit of vitamin A. That's why grazing animals who make their own vitamin A from plant foods, rather than eat another animal's liver, must munch on the stuff all day long. It's like trying to squeeze blood from a stone. Predators like humans pursue a riskier strategy of killing another animal and eating the liver, although this risk is balanced by the far easier job of obtaining vitamin A once we've acquired the food source.
Fortunately, liver is available in all kinds of forms and at all price levels. You don't have to import pate de foie gras -- even Oscar Mayer makes a great liver cheese that only costs around $4 for 8 one-ounce slices. I just have one slice a day, and that alone gets me far more than the RDA. I take a slice of salami, then a slice of liver cheese, then a slice of pepperoni, a tiny bit of mustard, some hard-boiled egg, and a little fire-roasted tomato from the can on top. It tastes wonderful. Then there's liverwurst and braunschweiger, unprocessed liver from calves, chickens, etc., and cod liver oil. I don't find the taste of liver bad, but it's not great on its own. Still, given how many forms it comes in, and how simple it is to work it into the rest of your meal, there's no excuse to exclude it from your diet.
Aside from getting it through your food, you can also apply vitamin A topically. It's the basis for many acne treatments and for creams that are clinically shown to reduce the appearance of fine lines and wrinkles. Just as with your diet, though, you have to apply it every day to maintain the effect. In lotions and sunscreens, it will be listed under the inactive ingredients as "retinyl palmitate." I looked over every skin lotion at my mega-supermarket, and only one brand had vitamin A -- the Gold Bond "Ultimate" line (I prefer the "softening" variety). I've also found only one face moisturizer that has vitamin A -- Neutrogena "healthy skin anti-wrinkle cream" (they call it by its technical name retinol). I found three sunscreens with vitamin A -- the cheapest was Banana Boat "Sport Performance Active Dry Protect," and I recall Aveeno and Hawaiian Tropic having some as well. These products aren't very expensive considering how long they last, and they don't take long to apply either. After eating some liver to fight aging from the inside, take a minute to send in reinforcements from the outside.
Lastly, it goes without saying that sugar is poison to the skin, and so is anything that turns into sugar in your bloodstream, like high levels of carbohydrates in your diet. There are two proteins responsible for giving skin its elasticity (elastin) and bounciness (collagen), and as with any protein they can get screwed up by a sugar smacking into them. Some proteins and sugars are meant to join together to form a more complex object, but you have to have the right protein, the right sugar, and an enzyme that carefully orchestrates the process to make sure things join in the right place. With lots of sugar flowing around, a protein and sugar that aren't meant to join could very well join, and even a pair meant to be together may get stuck in the wrong configuration, like putting a car's wheel where the gearshift should be.
These freak protein-sugar combinations can't do the jobs they were meant to do, and even worse, they can became tangled (or cross-linked) with each other. (This whole process is called glycation if glucose is the culprit and fructation if fructose is. The freak combinations are called AGEs -- Advanced Glycation End-products.) That's bad news for all proteins in your body, but the ones that keep your skin firm and bouncy are especially susceptible to getting screwed up by sugar. That's why a sugary diet ruins your skin, and why vegans always look dessicated. They eat a ton more fruit than the average person (who already eats a lot of carbs to begin with), and fructose is a stronger and faster destroyer of proteins than is glucose. It's no good to work liver into your diet if you're just going to sabotage its effects by wolfing down carbs and sugars or starches in particular.
In the end, it's a very simple and cheap formula to follow -- eat a slice of liver every day, take a few minutes to apply vitamin A topically, and go easy on carbs. You'll thank me when young girls continue to smile at you when you're in your 40s, rather than get grossed out by "old guy skin."