66 Therapeutic Cloning ence had uncovered the force of immortal renewal. It was an invisible thread that connected the generations, a lineage of microscopic primordial cells. The German scientist August Weismann clearly understood the implications of this observation. The cell theory implied that life on our planet today likely originated many millions of years ago from single-celled animals that were immortal. By immortal Weismann did not mean to imply that they could not be killed. Indeed, the struggle of the fittest implied that their less-fit cousins did indeed die. By ‘immortal’ Weismann meant only that they need not die – that given proper nutri- tion,  and  barring  some  accident,  any  particular  cell  could continue dividing, leaving no dead ancestors in its wake. Weismann then suggested that these original immortal cells may have clung to their daughter cells after dividing, thereby forming a small cluster of identical cells. It is then easy to imagine that these cells simply surrounded themselves with daughter  cells  to  aid  in  their  competition  for  immortality. One  could  imagine,  for  instance,  that  by  “holding  hands” in this manner, they were better able to move through the water, or perhaps better able to avoid being eaten by some other animal. SPECIALIZATION OF CELLS But  complex,  multicellular  animals  like  you  and  me  do leave dead ancestors behind. When and why did that happen? Here  is  where  Weismann  made  a  revolutionary  proposal. He surmised that some of the cells in this cluster changed in a profound manner. When the largest animal was still a small cluster of cells – perhaps something like the ball of cells called Volvox, the microscopic pond water animal – some of these primordial and immortal cells specialized in a subtle way