Programmed aging

In 2002, Severin and Hyman showed that a natural signal molecule (yeast pheromone) sex-specifically kills S. cerevisiae cells [3]. I suggested that this phenomenon can be regarded as a precedent of programmed death of a unicellular organism [4]. Later it was found in our group that the mechanism of such death strikingly resembles apoptosis of higher organisms [5]. To explain the pheromone effect on yeast in terms of the traditional concept of non-programmed death of organisms, Kirkwood and Melov [1] assumed that yeast cells form in fact a multicellular organism. Such an explanation is hardly sufficient since (i) programmed death phenomena are now also described in bacteria [6-9] and (ii) an additional function of a pheromone as an inducer of the organism's death program was discovered in a mammal, the small marsupial Antechinus stuartii.Male of this rodent uses pheromone to attract females and then to kill himself after run [10]. To define all cases of programmed death of organisms, in 1997 I suggested the term "phenoptosis" [11] (for discussion, see [7,9,12]).-link

Article on programmed aging theories.   In the above snippet, we see that in unicellular organisms and in some multicellular organisms programmed death can occur, strengthening the case for aging being programmed.