US researchers have found that a certain area of the human brain is hard-wired by evolution to preferentially respond to images of animals over other objects.
Co-author Ralph Adolphs explained that this adds to existing evidence that humans and animals are closely connected at a basic, instinctive level.
"The reasons for this are probably several, but would likely include the need to avoid predators and catch prey," Discovery News quoted Adolphs, a professor of psychology, neuroscience and biology at the California Institute of Technology, as saying.
"These abilities are at once critically important to survival and yet very difficult to do.
"Both predator and prey detection requires fast, real-time detection of shapes that are often camouflaged in a cluttered environment," he added.
Adolphs, project leader Florian Mormann, and their colleagues recorded how the brains of 41 neurosurgical patients undergoing epilepsy monitoring responded to images of people, landmarks, animals, or objects.
The scientists found that neurons in the right amygdala responded preferentially to pictures of animals, whether they were of cute little critters or threatening big beasts.he amygdalae are two almond-shaped groups of neurons located deep within the brain.
"The right amygdala has previously been implicated in the processing both of stimuli that are aversive and of stimuli that are rewarding," Mormann said.
"During our evolutionary past, animals could have represented either predator (aversive) or prey (rewarding). In either case, their behavioural relevance was pretty high," Mormann added.
The study appeared in the latest issue of Nature Neuroscience.