5.3 Behavior as a Cognitive Signal

Often, when we think about evolution, convergence, or homology, we use examples that are physiological – arm shape, flight, etc. But can convergence or homology apply to behavior?

Of course! Ultimately, behavior is the outward expression of an internal state. It might be a reflex to being touched by surprise, a look of fear when startled, or an expression of affection – even love. To do so, scientists ask, “What does [love] look like?” Once a behavior has been operationalized it becomes like any other trait to be studied.

If we think about Tinbergen’s Four Questions, we can create hypotheses about emotion. Let’s take anxiety. This is an emotion that nearly every species experiences to some degree. How is that possible? It’s quite simple, anxiety rooted in our fight or flight system. Something nearly every species possesses. After all, it is better to panic and run unnecessarily than be eaten, right?

Let’s consider how we might operationalize anxiety using Tinbergen.

• Mechanism (biology): Anxiety activates the stress response, also known as the HPA axis. This results in a release of epinephrine and cortisol, initiating the fight or flight system. The sensitivity of an individual organism’s fight or flight system is often tied to their baseline stress level.
• Ontogeny (development/culture): Different cultures and different homes perceive anxiety in different ways. The response to being anxious is often shaped by these outside pressures. Likewise, an animal, even us, raised in a high stress environment will often develop a higher baseline for cortisol and other hormones in their system. As a result, they may be prone to more overwhelming anxiety than others.
• Adaptive Value (persistence of the trait): As mentioned above, it is adaptive to run if you are stressed, frightened, or under attack. The benefit of survival outweighs any tendency to be laid back in the face of a threat. The exception to this might be species who have evolved strong defenses to common threats – animal or environmental.
• Phylogeny (evolutionary history): Because of its connection to the fight or flight system, anxiety is incredibly ancestral. Every mammal is prone to it, as are many other species. Dogs, horses, elephants, parrots – all can experience anxiety if their fight or flight is triggered without relief.

We could continue this exercise with any emotional or cognitive trait. The key to unpacking behavior in this way is to start by operationalizing the trait, then making sure to understand the EEA of the species whom you are addressing.

Communication

One of the most important emotional and cognitive signals for any animal is communication. That’s a big umbrella, right? There are so many potential ways to communicate, and even more reasons to do so.

It is important to understand why communication is such an important trait; and what happens if communication between individuals or groups fails.

Communication is at the core of everything! Mating strategies, raising offspring, cooperation, foraging in groups, you name it. Therefore, it makes sense that every species (even bacteria according to evolutionary biologist and primatologist Robert Sapolsky) evolves a way to communicate. More so, being able to communicate different internal states via one’s behavior provides important information to others in one’s environment. For example, if humans only had one form of communication, how would we distinguish ourselves as friend or foe? How does a dog mark their territory and communicate their reproductive status in one bodily fluid? The answer is in the mechanism. The answer is in variable communication.

Many species work cooperatively with conspecifics and heterospecifics. While there are many hypotheses on cooperation, the truth is that cooperation would not be possible without some way to share information about internal states. For this reason, communication as a trait is also incredibly ancestral. The varied ways it manifests depend upon the species.