The programmed death phenomena, aging, and the Samurai law of biology

Analysis of the programmed death phenomena from mitochondria (mitoptosis) t o whole organisms (phenoptosis) clearly shows that suicide programs are inh erent at various levels of organization of living systems. Such programs pe rform very important functions, purifying (i) cells from damaged (or unwant ed for other reasons) organelles, (ii) tissues from unwanted cells, (iii) o rganisms from organs transiently appearing during ontogenesis, and (iv) com munities of organisms from unwanted individuals. Defence against reactive o xygen species species (ROS) is probably one of primary evolutionary functio ns of programmed death mechanisms. So far, it seems that ROS play a key rol e in the mito-, apo-, organo- and phenoptoses. Here a concept is described which tries to unite Weismann's concept of aging as an adaptive programmed death mechanism and the alternative point of view considering aging as an i nevitable result of accumulation in an organism of occasional injuries. It is suggested that injury accumulation is monitored by special system sendin g a death signal to actuate a phenoptotic program when the number of injuri es reaches some critical level. The system in question is organized in such a way that the lethal case appears to be a result of phenoptosis long befo re occasional injuries make the functioning of the organism impossible. Thi s strategy is supposed to prevent the appearance of asocial monsters capabl e to ruining kin, community and entire population. These relationships are regarded as an example of the Samurai law of biology: 'It is better to die than to be wrong'. It is stressed that for humans these cruel regulations l ook like an atavism that should be overcome to prolong the human life span. (C) 2001 Elsevier Science Inc. All rights reserved.