In The Call of the Wild, it is demonstrated many times that animals, specifically dogs, have human-like emotions.
For example, "During the four years since... (Buck's) puppyhood, he had lived the life of a sated aristocrat; he had a fine pride in himself, was ever a trifle egotistical, as country gentlemen sometimes become because of their insular situation" (London 3). This quote compares Buck, a dog, to a human, specifically an aristocrat, in how he lives as a young dog. Being prideful and egotistical are complex emotions, often thought to be found solely in humans. The Call of the Wild shows that this is not the case.
Buck's experiences also show us that dogs, and potentially other animals show negative emotions as well. For instance, "Buck had accepted the rope with quiet dignity...But when the ends of rope were placed in the stranger's hands, he growled menacingly"(London 4). Buck shows a large range of emotions in this moment, changing from humility and acceptance to open hostility in a few seconds. This, however, pales in comparison to the reason for this change of emotion. Buck has no quarrel with the rope being in a familiar person's hands; it was only once a stranger held it that he grew upset. This shows that dogs also have very different feelings towards separate people based on familiarity, a human characteristic.
Another example of Buck's emotions is displayed when a large group of dogs brutally attack and kill Curly, another dog. "So sudden was it, and so unexpected, that Buck was taken aback" (London 15). This quotation shows clearly that dogs experience surprise.
Dogs also show loneliness and hopelessness. This is shown when Buck can not find the other dogs. "Miserable and disconsolate, he wandered about"(18). Because the other dogs are seemingly missing, Buck experiences the feeling of desolation.
One trait that we often consider a defining human characteristic is fear, particularly of that which we know little or nothing of. Surprisingly, Buck demonstrates this in The Call of the Wild. "Something wriggled under his feet. He sprang back, bristling and snarling, fearful of the unseen and unknown"(18). This is so startlingly similar to that which we define as human that civilized feelings are easily distinguishable in The Call of the Wild. We must, therefore, conclude that animals are capable of common human thoughts and emotions.