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The two theories; non-adaptive, and adaptive, are used to explain the evolution of senescence, which is the decline in reproduction with age. [8] The non-adaptive theory assumes that the evolutionary deterioration of human age occurs as a result of accumulation of deleterious mutations in the germline. [8]
Arrows show the vestigial structure called Darwin's tubercle. In the context of human evolution, vestigiality involves those traits occurring in humans that have lost all or most of their original function through evolution. Although structures called vestigial often appear functionless, they may retain lesser functions or develop minor new ones.
Vestigial structures are often homologous to structures that are functioning normally in other species. Therefore, vestigial structures can be considered evidence for evolution, the process by which beneficial heritable traits arise in populations over an extended period of time. The existence of vestigial traits can be attributed to changes in ...
The activity theory and the disengagement theory were the two major theories that outlined successful aging in the early 1960s. [4] The theory was developed by Robert J. Havighurst in 1961. [ 1 ] In 1964, Bernice Neugarten asserted that satisfaction in old age depended on active maintenance of personal relationships and endeavors.
A psychological adaptation is a functional, cognitive or behavioral trait that benefits an organism in its environment. Psychological adaptations fall under the scope of evolved psychological mechanisms (EPMs), [2] however, EPMs refer to a less restricted set. Psychological adaptations include only the functional traits that increase the ...
(a) The survival rate within a population decreases with age, while the reproduction rate remains constant.(b) The reproduction probability peaks early in life, at sexual maturity, and then steadily decreases as an individual ages, with the remaining share of the population decreasing with age as they enter the selection shadow.
Catarrhines lost the vomeronasal organ (or possibly reduced it to vestigial status). Proconsul was an early genus of catarrhine primates. They had a mixture of Old World monkey and ape characteristics. Proconsul's monkey-like features include thin tooth enamel, a light build with a narrow chest and short forelimbs, and an arboreal quadrupedal ...
Erik Erikson and Carl Jung proposed stage theories [2] [3] of human development that encompass the entire life span, and emphasized the potential for positive change very late in life. The concept of adulthood has legal and socio-cultural definitions. The legal definition [4] of an adult is a person