For those of you keeping track, that's two goodbyes apiece for friends and strangers, plus more planning than took place before the Yalta Conference. Finally, 20 or 30 minutes after my wife and I had the "Ready to go?" conversation that all couples have before leaving parties, we go.

When I'm at a party with my friends, I do the polite thing: I thank the host and leave. I do not say goodbye to anyone else unless they meet one of the following requirements: 1) They have been my best friend since we were 5 years old 2) They are dying and if I say goodbye now it will save me a trip to the hospital later.

I then drive home safely.

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Passing out at parties is harder when you have to find couch space for a second person.

When I leave a party with my wife I get in the car and mash the pedal so hard our windshield looks like the Millennium Falcon making the jump to light speed because I was ready to leave an hour ago and want to get the hell home now. Meanwhile she's in the passenger seat on the phone calling all of the people from the party she didn't get a chance to say goodbye to.

There might be a very good scientific reason for our diametrically opposed goodbye techniques.

In research published by Daniel Balliet, Norman P. Li, Shane J. Macfarlan and Mark Van Vugt of the American Psychological Association in Psychological Bulletin, men cooperate better with other men than women cooperate with other women. Researchers reviewed 272 studies containing 31,642 participants in 18 countries. Each study contained one social dilemma. In a social dilemma experiment, two or more people must choose between short-term self-interest and long-term group interest. The research revealed that women were more likely to cooperate when men were involved and women were less cooperative than men in same-sex situations.

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"We'll get right back to those Q3 numbers once Sandra closes her giant,
gaping vagina to every man in a three-block radius."

This reminds me of the BBC's Walking with Cavemen, a documentary that featured a shocking amount of caveman dong and also explained how cavemen lived. The men walked together. They hunted together. They scouted together. They fought in war together. It was in their interests to get along. The cavemen from the documentary were just like the guys from Entourage, with the main exception being that Vincent Chase is the only caveman dong on that show.

In the documentary, when a female named "Lucy" joined the group, she took a fancy to the alpha male in the group. The females, naturally, hated her guts and said things like "oog" (translation: "She's fat") and "ghuh" ("I hear she is on drugs") and "pit" ("Slut") and "pit-pit" ("Total slut").

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You don't even want to know what "sloog" means.

Lucy was ostracized by the females until the alpha female took Lucy under her wing in an attempt to keep her away from the alpha male. Because things like convents and boarding schools and Cheaters had yet to be invented, the alpha female eventually discovered Lucy and the alpha male overcoming their third-date jitters next to a boulder.

Eventually Lucy would die of random bludgeoning (random bludgeoning being the No. 1 cause of death in those days), but not before she gave birth to the alpha male's baby, forcing the females in the group to choose between legitimizing the baby by raising it or leaving it to die with its slutty mother, therein providing the inspiration for the first Lifetime original movie.

Lucy would go on to have a lucrative career as a corpse.

Evolutionary psychologists believe we are at least partly who we are today because of who we were on the savannah thousands of years ago. They say men are wired to accumulate resources and procreate and women are wired to compete for men. Of course, in the civilized world, we're beyond that now. Women don't depend on men solely for resources and can have a child without one. But their internal wiring was put in back when being labeled a bitch might be a death sentence.

So why do women take forever to leave parties? Maybe it's because, deep down, they have evolutionary trust issues. A woman isn't just saying goodbye at parties. She's subconsciously saying, "We're cool, right?" "We don't hate each other, right?" She's covering her bases because she knows that if she slights even one woman in the room, that woman could spend the rest of the party calling her a "pit-pit."

Of course. Reproductive decisions are more costly for females; they pay the higher costs of pregnancy and nursing.

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We're not sure what's going on here, but we know it's easier than a C-section.

When researchers put subjects in a more "self-protective" frame of mind, men and women became more loss averse. This could explain why so many people do not spend money in a bad economy even when they have money to spend.

According to evolutionary researchers, natural selection has endowed modern humans with a psychology that encourages us to make decisions that increase the likelihood that our genes will survive, thrive and replicate.

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Which is why you don't see so many pocket protectors these days.

What does that mean, in terms of money? It means men are more likely to spend money when sex is on the mind. Women are less loss averse when mating is not a factor; think of the older, married woman on a shopping spree. Fewer people invest in the stock market during hard times, even though that's when they should. Also, all of the hot young staffers chasing congressmen around Capitol Hill could explain why the country is broke.

If pop culture is to be believed, the bachelor party has evolved. A generation ago it represented the final opportunity for a man to sow his oats. Now it's a weekend of dude activities centered more on male bonding than on women. The bachelor party is no longer about sex. It's a going-away party. The unacknowledged in all this is that the friend you had when he was single will not be the same friend when he is married.

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"It's weird. For some reason, I hate beer pong and fight clubbing now."

A team of Michigan State researchers led by S. Alexandra Burt revealed that nice guys who don't exhibit antisocial (bad) behavior tend to marry more often than their wilder counterparts. On top of that, marriage reduces bad behavior.

Burt said it is unlikely that marriage inhibits antisocial behavior directly. She believes marriage leads to better social bonding and less time spent with idiot friends (my words, not hers). Another factor that seems important is marriage quality. Better marriages produce less antisocial behavior. This is why Fire Steve no longer sets things on fire with you in the woods since he got married.

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He sets things in the city on fire sometimes, but you can tell his heart isn't in it.

Why is there no good music on the radio? There are many reasons. Here's one you might not have thought of. Every song on the radio is about the same thing.

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Friday night and liquor-based oral hygiene, if we've been listening to the right stuff.

Research by University at Albany evolutionary psychologist Gordon Gallup and his student Dawn Hobbs shows that most popular songs are about getting it on (my words, not theirs). The study found that "Approximately 92 percent of the 174 songs that made it into the Top Ten in 2009 contained one or more reproductive messages, with an average of 10.49 reproductive phrases per song ... the most popular/bestselling songs contained significantly more reproductive messages."

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There's a reason he was the king of pop.

Why so many variations on the afternoon delight? Gallup writes, "Evolution is not about survival. It's about reproductive competition and the perpetuation of genes."

The lyrics are music to a gene's ears.

This is nothing new. An analysis of the lyrics of opera arias and art songs revealed many of the same reproductive messages extending back more than 400 years. A twisted variation of this phenomenon was explored in-depth in the excellent South Park Season 15 episode "Bro Down."

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We want to attend the shit out of some opera right now.

For more much-needed explanations, check out 6 Slacker Behaviors That Science Says Are Good For You and 6 Obnoxious Old People Habits (Explained by Science).