Mammals Some creatures in the world are classified as mammals due to the fact that they all have certain characteristics in common. All of them have vertebrae along their back and their spine. This helps to keep them safe and to be able to have a good chance of survival after an injury. This is known as their skeletal system even though some mammals only have a few bones while others have hundreds in their body. All mammals have sweat glands, the females can produce milk, and they have hair on their bodies. They have lungs that they use for breathing in and exhaling. The size of the lungs will vary depending on the size of the mammal. Yet they all operate in the same way. Mammals have bones for their middle ear which affects hearing, and the brain has a neocortex. It is believed the neocortex region is what allows many forms of mammals including humans and primates to have the intelligence that they do. It is believed this is the area of the brain that allows for personal development and reasoning so that a person can make their own choices rather than having a mechanical response. Not all of the actions of mammals have to do with survival. The most important element of being a mammal is the ability to give birth to live offspring instead of laying eggs. Most mammals will feed their baby off of the milk they produce when they are born. This means most mammals have offspring that are dependent upon them for a period of time. They also have a circulatory system that allows their blood to flow due to the activity of a heart with four chambers associated with it. As you may have already guessed humans are classified as mammals. Being a mammal though is just a general classification. There are many more details that are broken down to determine where they fit into the scheme of things. The number of mammals out there has dropped over time though due to many of them becoming extinct. This is often due to their natural environment being destroyed. These animals are gone and they will never again walk the Earth. Others are endangered which means if efforts aren’t taken to protect them they too will one day be all gone from this Earth as well.