Abstracts (first author)
Change of paradigm: aging is selected for, adaptive and programmed
It is shown that the so-called “evolutionary theories of aging” are based on circular reasoning and that their basic assumptions are flawed. A non-group-selective, evolutionary mechanism is elaborated that explains the co-selection and programming of reproduction and aging/death [Heininger K (2012) The germ-soma conflict theory of aging and death: Obituary to the “evolutionary theories of aging”. WebmedCentral AGING 3: WMC003275] Death of the soma is identified as the ultimate cost of reproduction. Importantly, germline cells control the longevity of the soma from ‘within’ by a variety of signals, e.g. sexual hormones. These signals limit the reproductive potential of the parent organism and drive a variety of aging pacemakers, particularly the senescene of the immune system. The transgenerational conflict between germline cells and soma over utilization of limited resources is the evolutionary rationale of postreproductive aging/death, semelparous organisms being a particularly drastic witness of the link between reproduction and death. Although the cost of reproduction, e.g. in terms of impaired immunocompetence and survival, still shapes the life history trade-offs of iteroparous organisms, the temporal uncoupling of reproduction and death concealed their evolutionary co-selection. In contrast to unitary organisms, modular organisms (e.g. plants, benthic aquatic invertebrates) that have no segregated germline and in which the adult body itself is a reproductive unit, may evade senescence. However, they are subject to territorial, density-dependent mortality patterns, due to e.g. self-thinning or chemical warfare, and density-limited seed recruitment driven by interindividual competition for resources. The germ-soma conflict shaped the different bauplans of unitary and modular organisms, is the motor driving animal coevolutionary Red Queen dynamics and fuelled the Cambrian explosion of animals.