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.
An organ can be as small as a lymph node, but a tissue may be as big as a muscle. So, tâ¦he more complex it is, being made of more than one type of tissue classifies it as an organ, whereas the similarity of all the cells being the same categorizes it as a tissue. Organs are things like hearts, lung, livers, etc.