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Animals also vary in the degree of coupling between oxidative phosphorylation and ATP production, the amount of saturated fat in mitochondrial membranes, the amount of DNA repair, and many other factors that affect maximum life span. [9] Furthermore, a number of species with high metabolic rate, like bats and birds, are long-lived.
There are numerous plants and animals for which the mortality rate has been observed to actually decrease with age, for all or part of the life cycle. [2] Hydra were observed for four years without any increase in mortality rate. [3] If the mortality rate remains constant, the rate determines the mean lifespan.
Study of negligibly senescent animals may provide clues that lead to better understanding of the aging process and influence theories of aging. [ 1 ] [ 3 ] The phenomenon of negligible senescence in some animals is a traditional argument for attempting to achieve similar negligible senescence in humans by technological means.
Telomerase is expressed by most vertebrates during embryonic stages but is generally absent from adult stages of life. [25] However, unlike vertebrates, lobsters express telomerase as adults through most tissue, which has been suggested to be related to their longevity. [26] [27] [28] Contrary to popular belief, lobsters are not immortal.
The Gaia hypothesis (/ ˈ ɡ aɪ. ə /), also known as the Gaia theory, Gaia paradigm, or the Gaia principle, proposes that living organisms interact with their inorganic surroundings on Earth to form a synergistic and self-regulating complex system that helps to maintain and perpetuate the conditions for life on the planet.
The earliest evidence for life on Earth includes: 3.8 billion-year-old biogenic hematite in a banded iron formation of the Nuvvuagittuq Greenstone Belt in Canada; [30] graphite in 3.7 billion-year-old metasedimentary rocks in western Greenland; [31] and microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia.
By another definition, however, maximum life span corresponds to the age at which the oldest known member of a species or experimental group has died. Calculation of the maximum life span in the latter sense depends upon the initial sample size. [1] Maximum life span contrasts with mean life span (average life span, life expectancy), and longevity.
All hexactinellids have the potential to grow to different sizes, but the average maximum growth is estimated to be around 32 centimeters long. Some grow past that length and continue to extend their length up to 1 meter long. The estimated life expectancy for hexactinellids that grow around 1 meter is approximately 200 years (Plyes).