Why You Should Tip Your Bartender from an Evolutionary Perspective: How Reciprocal Altruism Can Get You Tipsy.

I’ll scratch your back if you scratch mine.” We all know this mantra.  Actually, when executed properly, it’s the most efficient way to get things done.

Let’s take a moment to think about our ancestors.  It wouldn’t make sense for someone to share all of the berries they found or the meat they hunted with someone else.  Why bother?  It’s going to help ME survive if I save it all for myself.  Right?  The problem is that evolution is not about survival – it’s about reproduction.  The name of the game is passing on your genes.  Because of the inherent nature of evolutionary processes, cooperating is actually beneficial.  Sharing my berries with my child will increase reproductive success.  My genes are passed on, and my offspring get to grow and be healthy and continue the pattern.  This is known as kin-selected altruism – helping out and cooperating with family members.  Cooperation among kin increases overall reproductive success (Hamilton, 1964).  Ants all equally benefit from a reproductive standpoint when they each work for the queen.  Humans do reproductively better when we cooperate with our kin as well.  Studies have found that we share food more with our own kin than with non-relatives (Ziker & Schnegg, 2005).  It’s probably no surprise that we tend to leave our will with a close relative compared to friends or strangers (Cartwright, 2000).  Okay, so helping out the family makes sense.  What about non-relatives?

Research has pointed out that helping out non-relatives may be selected for as well (Trivers, 1971).  Reciprocal altruism is a type of social interaction in which one individual pays some cost or sacrifice to another with the expectation (however unconscious) that the same sacrifice will be made for that individual.  Paying a cost to a non-related recipient (buying my friend a gift) may benefit me if/when that individual pays me back someday (she buys me a gift).  Scratching someone else’s back today might benefit you someday when you’ve got an itch and need to call in a favor from that same person.  But what if that person never comes back to scratch your back?  What if that person receives the benefit, but never returns the cost?  We would call this person a cheater, but let’s face it – they’re winning here.  They got their back scratched, AND they didn’t have to do anything for it!  The problem with cheaters is that ultimately, all their bridges get burned.  Think back to our ancestors – suppose one day a lion comes up Grog the Caveman’s cave, and he has a weapon to take care of the issue and save his friend, Thak.  If Thak was a cheater, you think Grog would save him?  Thak has been eating Grog’s meat, borrowing Grog’s tools, and hogging Grog’s fireplace for a long time, all without ever helping out Grog in return.  Lot of I.O.U.’s, that Thak… He does not have Grog’s back when he needs him.  Paying any cost to Thak will never benefit Grog.  It makes more sense to consider giving Thak over to the lion for dinner…

So, what’s a more modern and fast-paced example of reciprocal altruism?  Hanging out at the bar, of course!  I can’t think of a quicker way to display this in action.  Patrons do not HAVE to pay their bartender a tip.  It’s encouraged and expected, but not enforced.  Someone could order a Long Island Iced Tea, watch me make it, pay for the drink in exact change, and then walk away.  And many people often do.  Here’s the problem… After about 3 Long Islands, I no longer feel like making these for you for free…. You’re out of luck.  The nature of being a bartender, or any waitstaff, is that tips are what pay the bills.  And that’s fine, until someone cheats the system.  Let’s use Joe as an example.  Joe could be the cheater, and it would work out for him for a while.  He would get his buzz cheaper than other tipping patrons.  Ultimately, this runs out though.  After Joe has established himself at every watering hole in town as the non-tipper, no bartender is going to serve him.  On a lighter note, those who tip are likely to get unexpected benefits often.  I’d be lying if I didn’t admit that, as the bartender, I often buy a round for my regular tipping customers.  It’s nice to do.  I don’t do it in hopes that they’ll scratch my back later, but quite often this is what happens.  It ends up in a nicer tip at the end of the night.  At the very least, tipping your bartender will keep him/her happy and eager to serve you throughout the night.  Reciprocal altruism can get you tipsy.  Now, I’m not saying that the only reason people do nice things is because we’re selfishly all hoping and expecting nice things to come our way afterwards.  I’m merely pointing out how this type of altruism has been selected for through evolution.  It can be adaptive.

The bottom line here is that you should tip your bartender.  It keeps them happy, and that keeps your drink stiff.


Cartwright, J. (2000). Evolution and human behavior: Darwinian perspectives on human nature. Massachusetts: MIT Press.

Hamilton, W.D. (1964). The evolution of social behavior. Journal Theoretical Biology, 7(1–16).

Trivers, R.L. (1971). The evolution of reciprocal altruism. Quarterly Review of Biology, 46(35–57).

Ziker, J., & Schnegg, M. (2005). Food sharing at meals: kinship, reciprocity, and clustering in the Taimyr Autonomous Okrug, Northern Russia. Human Nature16(2), 178-211.

Nicole Wedberg

About Nicole Wedberg

Nicole Wedberg is a Master’s student in the Psychology Department at SUNY New Paltz. While working on her thesis, she is also heavily involved in the Evolutionary Psychology lab where she assists with several research projects and oversees lab activity. As the Evolutionary Studies Assistant, Nicole is involved with everything evolutionary at New Paltz, and loves every minute of it. Her goal for this blog is to explore human nature while applying Darwinian theory to everyday human experience.
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