Altruism and Phenoptosis as Programs Supported by Evolution

Evolution of Longevity as a Species-Specific Trait in Mammals

From the evolutionary point of view, the priority problem for an individual is not longevity, but adaptation to the environment associated with the need for survival, food supply, and reproduction. We see two main vectors in the evolution of mammals. One is a short lifespan and numerous offspring ensuring reproductive success (r-strategy). The other one is development of valuable skills in order compete successfully (K-strategy). Species with the K-strategy should develop and enhance specific systems (anti-aging programs) aimed at increasing the reliability and adaptability, including lifespan. These systems are signaling cascades that provide cell repair and antioxidant defense. Hence, any arbitrarily selected long-living species should be characterized by manifestation to a different extent of the longevity-favoring traits (e.g., body size, brain development, sociality, activity of body repair and antioxidant defense systems, resistance to xenobiotics and tumor formation, presence of neotenic traits). Hereafter, we will call a set of such traits as the gerontological success of a species. Longevity is not equivalent to the evolutionary or reproductive success. This difference between these phenomena reaches its peak in mammals due to the development of endothermy and cephalization associated with the cerebral cortex expansion, which leads to the upregulated production of oxidative radicals by the mitochondria (and, consequently, accelerated aging), increase in the number of non-dividing differentiated cells, accumulation of the age-related damage in these cells, and development of neurodegenerative diseases. The article presents mathematical indicators used to assess the predisposition to longevity in different species (including the standard mortality rate and basal metabolic rate, as well as their derivatives). The properties of the evolution of mammals (including the differences between modern mammals and their ancestral forms) are also discussed.

Tracing Slow Phenoptosis to the Prenatal Stage in Social Vertebrates

Vladimir Skulachev's coining of the term "phenoptosis" 25 years ago (Skulachev, V. P., Biochemistry (Moscow), 62, 1997) highlighted the theoretical possibility that aging is a programmed process to speed the exit of individuals posing some danger to their social group. While rapid "acute phenoptosis" might occur at any age (e.g., to prevent spread of deadly infections), "slow phenoptosis" is generally considered to occur later in life in the form of chronic age-related disorders. However, recent research indicates that risks for such chronic disorders can be greatly raised by early life adversity, especially during the prenatal stage. Much of this research uses indicators of biological aging, the speeding or slowing of natural physiological deterioration in response to environmental inputs, leading to divergence from chronological age. Studies using biological aging indicators commonly find it is accelerated not only in older individuals with chronic disorders, but also in very young individuals with health problems. This review will explain how accelerated biological aging equates to slow phenoptosis. Its occurrence even in the prenatal stage is theoretically supported by W. D. Hamilton's proposal that offsprings detecting they have dangerous mutations should then automatically speed their demise, in order to improve their inclusive fitness by giving their parents the chance to produce other fitter siblings.