Have you noticed the phenomenon of puppy dog eyes, the inner eyebrow raising movement of dogs? Do you believe ita result of41for dogs to appeal to humans? Researchers dissected dog and wolf heads and found that the facial muscleanatomy of both animals was almost identical --42an eyebrow muscle, found only in dogs. The inner eyebrow raisingmovement makes the dogs’ eyes appear larger and more infant like,43prompts a “nurturing” response in humans.When dogs make the movement, it seems to elicit a strong desire in humans to44them. This would give the dogsthat moved their eyebrows more a selection advantage over others, reinforcing the trait in45generations. The findingsshow how important faces can be in capturing our attention, and how powerful facial expression can be in social interaction.