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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.
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
In biology, evolution is the process of change in all forms of life over generations, and evolutionary biology is the study of how evolution occurs. Biological populations evolve through genetic changes that correspond to changes in the organisms' observable traits.
Edward Hitchcock's fold-out paleontological chart in his 1840 Elementary Geology. Although tree-like diagrams have long been used to organise knowledge, and although branching diagrams known as claves ("keys") were omnipresent in eighteenth-century natural history, it appears that the earliest tree diagram of natural order was the 1801 "Arbre botanique" (Botanical Tree) of the French ...
So far, empirical research from a life course perspective has not resulted in the development of a formal theory. [8] Glen Elder theorized the life course as based on five key principles: life-span development, human agency, historical time and geographic place, timing of decisions, and linked lives. As a concept, a life course is defined as "a ...
Today, scientists agree that all current life descends from earlier life, which has become progressively more complex and diverse through Charles Darwin's mechanism of evolution by natural selection. Darwin wrote to J.D. Hooker on 29 March 1863 stating that "It is mere rubbish, thinking at present of the origin of life; one might as well think ...
A life history strategy is the "age- and stage-specific patterns" [2] and timing of events that make up an organism's life, such as birth, weaning, maturation, death, etc. [3] These events, notably juvenile development, age of sexual maturity, first reproduction, number of offspring and level of parental investment, senescence and death, depend ...
Generational change drives the cycle of turnings and determines its periodicity. As each generation ages into the next life phase (and a new social role) society's mood and behavior fundamentally change, giving rise to a new turning. Therefore, a symbiotic relationship exists between historical events and generational personas. Historical ...