There are various definitions for a human being. Biologically, they are classified as hominids of the species Homo sapiens, which are a primate species of mammal with a highly developed brain. Humans have the highest brain to body mass ratio of all large animals. They have a life expectancy approaching 80 years old in wealthy nations, walk on two feet and have opposable thumbs. Skin color ranges from almost back to pale pinkish-white. Height and weight varies, depending on locality, historical factors, environmental, and cultural factors such as diet.
Human beings are characterized by the ability to speak. They have a high capacity for abstract thinking and are commonly thought to possess a spirit or soul which transcends the physical body. The spiritual aspect of human beings is often defined in terms of rituals and religion. Theories involving the definition of the beginning of human life, evolution, and creationism are hotly debated topics in the law.
