Physical Appearance and Structure
Typical adult Humans are approximately 2 meters tall, and have two arms and two legs. They are warm-blooded omnivores with internal skeletons. Both hands have four fingers and one opposable thumb, which allows them to grip and use tools. Their arms are jointed at the shoulder, elbow and wrist. Their legs are similar, being jointed at the hip, knee and ankle. Humans walk upright. Human skin color varies over a wide range, including pale white and pink, tan, pale yellow, red, brown and black. This color does not change as the Human matures. Most Humans have hair covering the top and back of the head, and males also have hair on their chins and throats. Hair color varies from white and yellow to red, brown and black, gradually changing to gray as the Human ages. Human females have only one pair of memories which they use to nurse their young.
Humans have color vision, sensing the spectrum between infrared and ultraviolet wavelengths. They have good depth and motion perception. Their hearing covers a range from 16 to 27,000 cycles per second, with good separation and direction-sensing qualities. Their skin is touch-sensitive. Their senses of taste and smell are not as highly developed as their sight.