The species theory, polygenism, held that human races were of different lineages and suggested a hierarchy outlined in the Chain of Being that positioned Africans between man and lower primates.
No, they are involved in the Circulatory System which is responsible for pumping and channelling blood to and from the body and lungs with heart, blood and blood vessels. no veins are not considered an organ because they are a grouping of different tissues like a organ.
There are many different types of cells, but all have the same basic structure. Tissues are layers of similar cells that perform a specific function. The different kinds of tissues group together to form organs. There are four basic types of tissue: Connective tissue supports other tissues and binds them together.ome tissues become lumpy (nodular) or more rigid. Because of cell and tissue changes, your organs also change as you age. Aging organs slowly lose function. Most people do not notice this loss, because you rarely need to use your organs to their fullest ability.