In one sentence, describe what the following article is about:

In a study on empathy in pigs, researchers looked at how pigs responded when their pen mates were placed in stressful or potentially harmful situations. When one group of pigs were in danger or experiencing a threat, the other group responded with stress signals like pushing their ears back and becoming more alert. This indicates that pigs have the ability to show emotional contagion, where they share the emotional response that another pig is having, which is a key part to having the capacity for empathy. While you may not want to conduct your own test on animals, you can observe if the animal reacts when another animal appears in danger or under stress. The animal may respond with stress related noises or actions, such as a more alert or rigid body movements, cries or howls, and moving towards the animal under stress. In a study on empathy in elephants, a researcher observed an elephant mother who gave birth to a stillborn baby. The mother then guarded her dead calf for two days and tried several times to revive the dead calf's body. When the researcher offered the elephant mother water, the elephant drank the water and then touched her chest as if in a sign of mourning. Though elephants have been one of the more studied animals in terms of empathy, an animal may display empathy by trying to protect an injured animal from a predator. The animal may also respond to a dead animal by displaying signs of mourning over their body or to others, such as the elephant mother touching her chest. Often, animals of the same species will protect each other and respond to the needs of their herd or pack. You may observe animals working together to build a habitat, such as a den, or you may observe animals working as a team to capture a prey or elude a predator. These group related activities can be a sign of empathy among the animals, as they must focus on how their fellow animals are thinking and feeling and respond to it in kind.
Look to see if the animal reacts to another animal when they are stressed or in danger. Note if the animal responds to an injured animal or a dead animal in the area. Check if the animal works together with other animals.