Many bird and reptile species use hissing as a threat device against potential predators. The way these species produ...

AndreaK on October 15, 2019

Hi @ali,

Here we have a question that asks us to help resolve the apparent discrepancy. Essentially, what this question stem means is that the information presented in the stimulus seems inherently contradictory, and our job is to choose an answer that helps repair the confusion and explain how two seemingly contradictory things could both be the case at the same time.

Let's take a minute to think about what this would mean in this question.

We know from the premises and birds and reptiles both use hissing as a threat device, and that this trait likely developed in an early common ancestor. However, at the time this common ancestor was around none of its predators could hear hissing.


Funny, right? That hissing would be a threat device against predators that can't even hear it?

We want our brain to be cranking out ideas of ways that hissing could still be a threat device even though it couldn't be heard. Remember our goal - to explain how two incompatible ideas could actually be compatible.

I'm picturing a bearded dragon that somebody pestered and made angry (If you aren't familiar, try giving it a Google!). Their "beards" are flaps of skin that spike out around their face and make them look bigger when they're hissing at something, which is what they do when they feel threatened.

What if just the sight of a bigger, spikier lizard is enough to scare a predator off?

Even if you don't know what a bearded dragon looks like, we see lots of examples of this in the animal kingdom. For hikers in bear country, the rule of thumb if you ever encounter a bear in the wild is to stand up tall, make loud noises, wave your arms and try to make yourself look as big and threatening as possible to scare the bear off.

Even if a predator couldn't hear, it could still see a bigger, angrier looking you (or bearded dragon!). Maybe that's enough to serve as a defense mechanism against threats.

Answer choice C gets at this idea and reconciles these two seemingly incompatible traits.

Hope this helps you understand the right answer better!