The Role of Tumors in the Origin of New Cell Types Tissues and Organs. Evolution by Tumor Neofunctionalization explores the possibility of the positive role of tumors in evolution of multicellular organisms. This unique perspective goes beyond recent publications on how evolution may influence tumors, to consider the possible role of tumors in evolution.Widespread in nature tumors represent a much broader category than malignant tumors only. The majority of tumors in humans and other animals may never undergo malignant transformation. Tumors may differentiate with the loss of malignancy, and malignant tumors may