Human

Humans (Homo sapiens) are bipedal sapient mammals native to planet Earth. They are omnivorous and generally believed to have descended from arboreal ancestors.

Biology
Humans have an erect posture, with two legs, two arms and a head which comprises the brain and most of the sense organs. Extraterrestrial species showing this same body plan, or a very similar one, are collectively known as humanoids. Although some humanoid races look almost exactly like humans, as is the case with Vulcans, they are often very different internally. Vulcans, for example, have green blood containing copper, while the Human blood is red and contains iron.

Humans are carbon-based lifeforms, and have an internal skeleton containing calcium, which gives the bones strength and durability. More than 60% of the Human body is composed of liquid water. Their circulatory system is closed and they have a heart and two lungs (though they are able to survive with only one lung), located in the chest area. They have five fingers on their hands and five toes on their feet.

Despite having evolved as a predatory species, Humans are generally considered weak and not well adapted to hunt without the aid of tools. Their canine teeth, for example, are not sharp like those of their evolutionary relatives, the other Earth primates, and their fingers and toes have nails, rather than claws.