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.
Rating Newest Oldest. Best Answer: A Tissue is an aggregation of cells more or less similar morphologically and functionally. The animal body is composed of four primary tissues, namely, epithelium, connective tissue (including bone, cartilage, and blood), muscle, and nervous tissue.- Blood is a tissue comprised of four components: plasma, red and white blood cells and platelets.It is connective tissue. (i.e. cells of connective tissue (blood) separated by an inorganic material (plasma). Plasma is the extracellular matrix that includes everything but the red/white blood cells.-.ating Newest Oldest. Best Answer: A Tissue is an aggregation of cells more or less similar morphologically and functionally. The animal body is composed of four primary tissues, namely, epithelium, connective tissue (including bone, cartilage, and blood), muscle, and nervous tissue.