For all of humanity's achievements — and for all the perks of supersized brains and opposable thumbery — we still have a lot to learn from some of this planet's tiniest residents.

For instance, we still can't wrap our heads around the modern traffic jam — while, no matter how many ants share the road, they never get stuck in bumper-to-antennae traffic.

And now, it seems ants are schooling us on civilization's most elementary building block: how to get along with others.

Let's face it. We've never been very good at it. We're quick to wax indignant. We're in a perennial state of outrage. And our knee-jerk reactions to newcomers are often catastrophically wrong.

For the humble ant, on the other hand, things are much more black and white.

That's because, according to a new study from Vanderbilt University, an ant's interpersonal skills are hardwired to its DNA.

The research, published this month in the Journal of Experimental Biology, suggests that ants determine whether a newcomer is a friend or foe based on how certain chemical markers are decoded in their brain.

And it's a key factor in whether an ant goes to war or keeps the peace. For colony-dwelling, or eusocial, creatures it's crucial that they get it right.

"Eusocial ants are one of the biggest success stories in evolutionary biology, thanks in no small part to their advanced organizational behaviors and complex social interactions," senior author and biologist Laurence Zwiebel explains in a news release. "For years, researchers have hypothesized that ants have specific chemical markers which play key roles in their interactions. What surprised us is that ants not only have these markers, but require these signals be very precisely decoded by specific receptors to trigger aggression."

Ants working as a team to send worms to each other. Ant civilization was built (mostly) on cooperation. (Photo: Pattarapong phulom/Shutterstock)

While we may rely on our wobbly prejudices or gut feeling to determine if a newcomer means us harm, ants make it a strictly biological affair. They can literally sniff out trouble. And trouble-makers generously leave a specific odorant in their wake to make it even more convenient.

The newcomer ant may be a nestmate. Or a nest marauder. The complex blend of scents it bears — what Zwiebel calls a "coat of many odors" — will reveal its intentions. The ant takes a sniff, decodes those chemical compounds and makes a snap, but accurate, decision: Either issue a call to arms or a high-five and welcome home.

And the best part about that lock-and-key system? The researchers found the ants they studied — from nine distinct colonies collected across the Florida Keys — had to be specifically triggered to be aggressive.

Their default setting was acceptance.

"Accepting friends and rejecting foes is one of the most important decisions an ant worker must make," lead author Stephen Ferguson explains in the release. "Our study finds that unless there is a clear and unambiguous threat, ants are more likely to be accepting than they are to be aggressive. This process may have contributed to the evolutionary success of these insects, and there may be important lessons about tempering aggression for other social beings such as humans."

Ants have a brilliant strategy for determining friend from foe
Ants determine if a newcomer is a friend or foe based on how certain chemical markers are decoded in their brain — and getting along is the default setting.