A similar effect was seen when a several different tissues in adult humans were found to possess stem cells, cells that are theoretically immortal and could possibly be used to produce virtually any tissue in the body. Despite the flurry of articles written about the potential and ethics of these technologies, comparatively little has been written about the science they are based on. In this class we will look at the biology behind cloning and stem cells by examining the primary literature. Most people believe that animal cloning is a new technology. This is actually far from the truth.
Cloning occurs naturally and is widespread in both animals and plants.
It is also the primary means by which most unicellular organisms reproduce. The first experiments involving artificial cloning were carried out during the golden age of embryology in the 1800's. Even the modern techniques used to clone animals today were first carried out in the late 1940s. What is new is that our skill and technology has improved to the point where it is now possible to clone large mammals from adult cells. Since this implies that cloning could be applied to humans as well, this has generated a great deal of interest in the general public.