Experts tell us whether animals cry when they are sadScience and technology05:15 | 05 March 2024

Tears are beneficial for our eyes and those of many other animals. Most mammals, reptiles and birds have lacrimal glands that secrete a watery fluid. The exact concentrations of the biochemical components of tears vary between animal species, and they have also evolved to adapt to their environments.

There are three types of tears. These are basal tears (the glands secrete them spontaneously and form a protective nutrient film on the cornea), reflex tears (formed in response to external stimuli: for example, eye injury), emotional tears (caused by a mental state).

There are many hypotheses about why we cry. A good cry can help us cope by signaling emotional pain, stress, or vulnerability. Our tears can influence those around us by strengthening social relationships, encouraging cooperation and suppressing aggression, or by making others feel caring, helpful or protective.

Today, scientists agree that emotional tears are truly unique to humans. Although there are scientific facts that show that animals have something similar, but in a different form. For example, although many adult animals see no benefit in showing weakness, many young animals cry without tears as a signal to their mothers. When young bucks are stressed and hungry, they produce a secretion from a gland just below the eye to which their mothers respond.

In a 2022 study, researchers found that dogs shed tears when reunited with their owners. The oxytocin hormone, which is responsible for maintaining communication, triggers this reaction.

Researchers have also documented domestic pigs “crying” in poor farm conditions. This is especially noticeable in the form of a strong red spot under the eyes. In pigs, this discharge also occurs as a result of stress. Rats exhibit the same phenomenon, sometimes referred to as “blood tears.” This reaction intensifies under stress.