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.
Introduction A tissue is a group of similar cells that function together to perform a specialized activity. There are four kinds of tissues: 1  Epithelial tissue = covers body surfaces; lines body cavities, hollow organs, and ducts; and forms glands.2  Connective tissue = protects and supports the body and its organs; binds organs together, stores energy reserves as fat, and provides immunity. A gland may consist of one cell or a group of highly specialized epithelial cells that secrete substances into: ducts. 2  onto a surface. 3  into the blood. 4  Exocrine glands-The secretions of exocrine glands flow onto the free surface of covering and lining epithelia, usually by way of tubelike ducts.