Good hair days have long been known to govern the emotions of angst-ridden teenagers as well as adults, but what really goes into the science of a good hair day? While it would be easy to dismiss a good hair day as something fleeting and superficial, it turns out that good hair may well go quite a bit deeper than that.

Science has long taught us that our physical appearance matters. Visible evidence of youth, cleanliness, and health signal fertility and vitality to our potential mates. Healthy, beautiful hair has always played an important role in the mating game. After all, where would Samson be were it not for his long locks, shorn prematurely, or the vixen Cleopatra without her lustrous black mane? Hair has undeniably been a crucial part of our physical appearance, so it’s no wonder that it continues to be so today.

The health of a newborn is often judged by the thickness and luster of his or her hair. Women with shiny, vibrant hair are considered more sensual and attractive. As we age, our hair naturally thins and loses shine, and that hair loss is associated with a decrease of virility, fertility and health. Dull, thin hair is just not considered desirable or sexy.

A full head of shiny, healthy hair can also be aesthetically pleasing as it frames our faces. Studies show us that babies are naturally drawn to faces, and humans seek faces all around them. Hair is often a basic descriptive factor when we are describing ourselves or others, and taking care of it can be an essential part of taking care of ourselves.

When it comes right down to it, having healthy, shiny, beautiful hair can be tightly interwoven with our self-esteem. We can play with our hair, style it, cut it, dye it, and alter its texture to create a look we feel is more flattering to our overall appearance. Our hair can give us more confidence and provide us with a sense of control, even in the face of aging. Today’s beauty products can even challenge the inevitable changes associated with aging, such as hair loss or graying, and we can fight back, maintaining thick, gorgeous hair well into our golden years.

What does a good hair day mean to you? While it may not necessarily be healthy to let a bad hair day ruin your entire outlook, it is perfectly fine and even biologically normal to have a little extra bounce in your step on good hair days. Now let your hair down, and strut your stuff. You know you look amazing.

What has science done for the beauty industry lately, you ask?

Well, for one, scientists in Australia have recently discovered a “curly hair gene,” AKA the trichohyalin gene. This gene, discovered by scientists at the Queensland Institute of Medical Research (QIMR), is the one responsible for creating straight or curly locks.

Based on research done in Europe by Professor Nick Martin and Dr. Sarah Medland of the QIMR, 45 percent of Europeans have straight hair, 40 percent have wavy hair and only 15 percent have curly hair. As a curly-haired guy, himself, Professor Martin wondered what genetic variations were responsible for hair texture.

To learn more about these genetic processes, the team analyzed data collected from a 30-year study of 5,000 twins in Australia. When the twins’ genome maps were compared, twins exhibited the same types of variations in the trichohyalin gene depending on if they shared either curly hair or straight hair.

What else has Professor Martin concluded? Because the trichohyalin gene creates an amino acid change, which in turn influences the hair’s texture, it may be possible to develop treatments to make hair straighter or curlier as an alternative to heated hair straighteners or chemical hair treatments like perms. Maybe someday soon, we’ll all be popping pills instead of ironing out those curls every day or heading to the salon for a perm. (Of course, you could always embrace your natural curl instead!)

Science. What will they think of next?

My diet is crappy, but it helps my girlfriend’s hair look sassy.

Being a guy bound to a beauty merchandiser at a local high-end salon means that I am constantly serving as resident guinea pig. My life is a tumultuous parade of trial sizes, courtesy of my buy-curious girlfriend who’s obsessed with beauty products.

So when she brought home some news along with her over-stuffed goodie bag from a day’s work, my interest was piqued (mainly because my bad habits would actually help for once). “Digame Por qué?” says I, in broken Spanish.

My girlfriend answered that Kayla Fioravanti RA, Chief Formulator and co-founder of Essential Wholesale had shared some insight with her about everyday items in our kitchens that may be used for adding softness, control and shine to our hair.

Even better news is the fact that I am a normal slob of a man who over-consumes all of these hairstylist helpers on a regular basis. And now I have an excuse to over-indulge even more in the interest of keeping the sassy do of my domestic goddess shiny and sheer.

What are the top three tasty kitchen items that can help work wonders on your head and shoulders?

1. Real Mayonnaise. It’s a conditioner that’s not just for sloppy sandwiches. All you do is dampen your hair, apply a thick layer of mayonnaise from your scalp to the ends of your hair. Comb it until you have lots of creamy coverage and then sit back and let it dry for 20 minutes. Be sure to keep your hungry domestic partner at bay until you’re ready to wash it out. All you have to do after that is rinse and shampoo.

2. Salt. It’s the favorite non-liquid flavor of sports fans everywhere. It’s also a great ingredient to giving your hair amazing volume and control. You can boost the body in your hair by adding a tablespoon of salt to 4 oz of water in an empty spray bottle. After washing and conditioning, spray this mixture over your hair and allow some time for it to air dry.

3. Beer. Obviously the thought of having more beer in the house just so my girlfriend could retain some shine made me extremely happy. The fact that the best conditions to use it are when it’s warm and flat (meaning, my leftovers) is glorious news indeed. So I started donating my leftovers of flat, warm beer into her shower container. It worked amazingly. Now that’s what I call synergy.

When Chris Rock’s daughter, Lola, came to him crying and asked, “Daddy, how come I don’t have good hair?” the bewildered comic committed himself to figuring out the complex answer to his daughter’s simple, but profound question.

In the documentary film, Good Hair, Rock takes us on a fascinating journey through the international business trade of hair weaves, the science behind relaxers and the surprising question of how much black women spend on their hair.

During a press junket for a film festival in Salt Lake City, Rock discussed with Salon Magazine journalist Andrew O’Hehir how the initial idea for the film expanded the further he investigated.

“It kind of blew my mind, the idea that in an African-American household you got this Porsche that nobody can see, these working-class and middle-class black women spending thousands of dollars… buying a Porsche that nobody sees.” He adds, “There is a whole economic realm to this that I didn’t know about at all.”

One unexpected turn in the economic story comes when Rock learns that much of the hair used for creating extensions for black women comes from India. Human hair is India’s single largest export. He also sees how the culture has adapted to make harvesting the hair easy and profitable for the industry. Many Hindu temples conduct “hair sacrifices” during religious ceremonies that allow members of the temple a few moments of cultural distinction (and no money) in exchange for hair that can later be worth thousands of dollars. This “sacrificed” hair is processed and sold to hair dealers around the world who, in turn, sell it to local dealers who, in turn, sell it to salons and hair vendors at a huge profit.

How does Rock view this suspicious economic angle? He tells O’Hehir a different cut of the movie exists where Rock treats the hair trade as a problem for black females. He later calls on women to reject this international cartel of exploitation. But, he says, in the end that version simply wasn’t as fun to watch. He said he would rather inform and entertain rather than divide and mobilize.

On that tip, Rock succeeds. The movie is a serious, yet non-confrontational look at how cultural norms can make us do and believe some crazy things. It’s entertaining, but not angry. Celebrities such as Ice-T, Nia Long, Paul Mooney, Raven Symoné, Maya Angelou, and Reverend Al Sharpton all candidly offer their stories and observations that add much more entertainment to what could have become a sobering, but impersonal look into the culture of beauty in the world.

For anyone involved in cosmetology, hairstyling or ethnic beauty marketing, this film is a must. Good Hair is playing in select cities right now. It opens nationally on October 23.