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.
A vein is an elastic blood vessel that transports blood from various regions of the body to the heart. Veins can be categorized into four main types: pulmonary, systemic, superficial, and deep veins.Pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart.Systemic veins return deoxygenated blood from the rest of the body to the right atrium of the heart. Superficial veins are located close to the surface of the skin and are not located near a corresponding artery.Deep veins are located deep within muscle tissue and are typically located near a corresponding artery with the same name (for example coronary arteries and veins). vein can range in size from 1 millimeter to 1-1.5 centimeters in diameter. The smallest veins in the body are called venules. They receive blood from the arteries via the arterioles and capillaries.