Sheep belong to the Ovis subfamily, Mammalia, Artiodactyla, Bovidae, and are commonly raised as livestock by humans. Their wool is typically white in color. Originally native to the mountains in the northern hemisphere, sheep are closely related to goats.

Humans and many animals have pupils that adjust to the intensity of light entering their eyes through the pupillary reflex. We tend to think of pupils as round, as most eyes have round pupils like ours. However, the pupils of ungulates, such as goats and sheep, are almost rectangular.

This shape provides them with a field of vision of up to 340 degrees, compared to humans' 160-210 degree field of vision, enabling them to see almost everything around them without turning their heads.

The rectangular shape also helps them to see better at night due to larger pupils and sleep more soundly during the day.

Sheep have a long history of coexisting with humans and are one of the first animals raised by humans. They are ideal hunting targets due to their moderate size and low attack power. Sheep are docile, easy to tame, and have the ability to produce milk, meat, wool, and skin.

While often regarded as unintelligent animals, sheep have demonstrated surprising intelligence. They can identify and eat foods that can treat diseases when they are sick, and they have an excellent memory and can recognize and remember human faces and distinguish between emotions.

In Portland, USA, locals like to hire a flock of sheep to graze in the park as "live weed mowers." These animals do not make noise, and they do not cause environmental damage by spraying pesticides.

Sheep are also being labeled as sources of greenhouse gas emissions in today's world of global warming. Artiodactyls such as sheep and cattle produce 90% of the methane from the rumen and excrete it in the form of belches.

To combat climate change, Australian scientists are working to breed "green" sheep that burp less by identifying the genes that cause some sheep to burp less often than others.

Despite being proven to be intelligent animals, sheep are still commonly thought of as "weeding machines" or livestock. However, they are much more than that. For example, scientists have found that sheep have unique personalities, much like humans.

Sheep have been shown to express emotions such as joy, anger, and even jealousy. They also exhibit traits such as playfulness and curiosity. By understanding the complexities of sheep behavior, humans can better care for them and improve their well-being.

Furthermore, sheep are used in scientific research and are helping researchers better understand the mechanisms behind various diseases. For example, researchers are studying the causes of scrapie, a disease that affects the nervous system of sheep and goats and is similar to mad cow disease.

Sheep have also been used in the development of insulin, a hormone used to treat diabetes. Scientists discovered that sheep pancreases produce insulin, leading to the production of insulin for human use.

Sheep are fascinating animals that have been closely associated with humans for thousands of years. They exhibit a range of behaviors and intelligence that we are only just beginning to understand.

As we continue to learn about sheep, we can find ways to better care for them and use them to improve human health and well-being.