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Earth remains the only place in the universe known to harbor life. Geochemical and fossil evidence from the Earth informs most studies of abiogenesis. The Earth was formed at 4.54 Gya, and the earliest evidence of life on Earth dates from at least 3.8 Gya from Western Australia.
Direct evidence of this is an experimental procedure in molecular biology known as alanine scanning. A hypothetical "Proline World" would create a possible alternative life with the genetic code based on the proline chemical scaffold as the protein backbone.
Biology is the overall natural science that studies life, with the other life sciences as its sub-disciplines. Some life sciences focus on a specific type of organism. For example, zoology is the study of animals, while botany is the study of plants. Other life sciences focus on aspects common to all or many life forms, such as anatomy and ...
Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from matter that does not. It is defined descriptively by the capacity for homeostasis, organisation, metabolism, growth, adaptation, response to stimuli, and reproduction.
Alternatives to Darwinian evolution have been proposed by scholars investigating biology to explain signs of evolution and the relatedness of different groups of living things. The alternatives in question do not deny that evolutionary changes over time are the origin of the diversity of life, nor that the organisms alive today share a common ...
Concluding that evidence of an extraterrestrial life form (past or present) has been discovered requires proving that a possible biosignature was produced by the activities or remains of life. [1] As with most scientific discoveries, discovery of a biosignature will require evidence building up until no other explanation exists.
Over a 45-years span — between 1975 and 2020 — improvements in cancer screenings and prevention strategies have reduced deaths from five common cancers more than any advances in treatments ...
Social-science methodologist Donald T. Campbell, who emphasized hypothesis testing throughout his career, later increasingly emphasized that the essence of science is "not experimentation per se" but instead the iterative competition of "plausible rival hypotheses", a process that at any given phase may start from evidence or may start from ...