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Ecological systems theory is a broad term used to capture the theoretical contributions of developmental psychologist Urie Bronfenbrenner. [1] Bronfenbrenner developed the foundations of the theory throughout his career, [2] published a major statement of the theory in American Psychologist, [3] articulated it in a series of propositions and hypotheses in his most cited book, The Ecology of ...
There is no single generally accepted model for the origin of life. Scientists have proposed several plausible hypotheses which share some common elements. While differing in details, these hypotheses are based on the framework laid out by Alexander Oparin (in 1924) and John Haldane (in 1929), that the first molecules constituting the earliest ...
The PAH world hypothesis is a speculative hypothesis that proposes that polycyclic aromatic hydrocarbons (PAHs), known to be abundant in the universe, [178] [179] [180] including in comets, [181] and assumed to be abundant in the primordial soup of the early Earth, played a major role in the origin of life by mediating the synthesis of RNA ...
They were able to produce statistical models of population genetics that included Darwin's concept of natural selection as the driving force of evolution. [ 44 ] Developments in genetics persuaded field naturalists such as Bernhard Rensch and Ernst Mayr to abandon neo-Lamarckian ideas about evolution in the early 1930s. [ 45 ]
Erasmus was an early proponent of what we now refer to as "adaptations", albeit through a different transformist mechanism – he argued that sexual reproduction could pass on acquired traits through the father’s contribution to the embryon. These changes, he believed, were mainly driven by the three great needs of life: lust, food, and security.
The Asymmetry, also known as ' the Procreation Asymmetry ', [1] is the idea in population ethics that there is a moral or evaluative asymmetry between bringing into existence individuals with good or bad lives. [2] It was first discussed by Jan Narveson in 1967, and Jeff McMahan coined the term 'the Asymmetry' in 1981. [3]
Another database, TimeTree, helps biologists to evaluate phylogeny and divergence times. [31] In 2016, a new tree of life (unrooted), summarising the evolution of all known life forms, was published, illustrating the latest genetic findings that the branches were mainly composed of bacteria. The new study incorporated over a thousand newly ...
In the 1928 book The Nature of the Physical World, which helped to popularize the concept, Eddington stated: . Let us draw an arrow arbitrarily. If as we follow the arrow we find more and more of the random element in the state of the world, then the arrow is pointing towards the future; if the random element decreases the arrow points towards the past.