Trying to determine how an animal thinks has been futile in most cases—especially efforts focused on how to translate their barks, chirps, and sundry other noises. Scientists realized that it would involve scanning the brain of the animal with instruments such as a functional Magnetic Resonance Imaging (fMRI) while performing a cognitive task. And while human brain studies using an MRI are common, such experiments on other animals are not as common. One main reason was because putting an animal under sedation defeats the purpose of checking out their brain in response to certain stimuli. In 2012, scientists reasoned that dogs that underwent extensive training—such as for the Navy Seals—would not be as “wild” as dogs that were not trained as rigorously. They were able to get two well-trained dogs into an MRI and monitor the animals’ reactions. They did find a human-canine “connection”: After training for specific signals to get a treat, when the dogs saw such a treat signal, the part of the brain called the caudate region showed activity—and in humans, this region is associated with rewards.

In the past decade, scientists have tried to understand how and why human babies and other animals develop language. For example, in one experiment, scientists compared language discrimination in human newborns and cotton-top tamarin monkeys. Each group was presented with twenty sentences in Japanese and twenty sentences in Dutch. Infant reactions were gauged by their interest in sucking on a pacifier; when infants first heard sentences in Dutch, they sucked rapidly on their pacifiers, but after a while they grew bored with the Dutch sentences and the rate of sucking slowed. When someone started speaking in Japanese, they showed increased interest by increasing their rate of sucking.

Language discrimination was studied in tamarin monkeys by changes in the facial orientation toward or away from the loudspeaker. Similar to the infant reactions, the monkeys looked at a loudspeaker broadcasting Dutch sentences and looked away when bored. When someone started speaking Japanese sentences, they looked back at the loudspeaker. Results indicate shared sensitivities between monkeys and humans in the ability to discriminate between languages.