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In biology, an identification key, taxonomic key, or frequently just key, is a printed or computer-aided device that aids in the identification of biological organisms. Historically, the most common type of identification key is the dichotomous key, a type of single-access key which offers a fixed sequence of identification steps, each with two ...
Extraterrestrial life, or alien life (colloquially, alien), is life which does not originate from Earth. No extraterrestrial life has yet been scientifically conclusively detected. Such life might range from simple forms such as prokaryotes to intelligent beings, possibly bringing forth civilizations that might be far more advanced than humans.
The cultural impact of extraterrestrial contact is the corpus of changes to terrestrial science, technology, religion, politics, and ecosystems resulting from contact with an extraterrestrial civilization. This concept is closely related to the search for extraterrestrial intelligence (SETI), which attempts to locate intelligent life as opposed ...
Nucleic acids may not be the only biomolecules in the universe capable of coding for life processes. [1]Astrobiology (also xenology or exobiology) is a scientific field within the life and environmental sciences that studies the origins, early evolution, distribution, and future of life in the universe by investigating its deterministic conditions and contingent events. [2]
Single-access key. In phylogenetics, a single-access key (also called dichotomous key, sequential key, analytical key, [1] or pathway key) is an identification key where the sequence and structure of identification steps is fixed by the author of the key. At each point in the decision process, multiple alternatives are offered, each leading to ...
The Three-Body Problem (Chinese: 三体; lit. 'three body') is a 2008 novel by the Chinese science fiction author Liu Cixin. It is the first novel in the Remembrance of Earth's Past trilogy. [1] The series portrays a fictional past, present, and future wherein Earth encounters an alien civilization from a nearby system of three Sun-like stars ...
Communication with extraterrestrial intelligence (CETI) is a branch of the search for extraterrestrial intelligence that focuses on composing and deciphering messages that could theoretically be understood by another technological civilization. The best-known CETI experiment was the 1974 Arecibo message composed by Frank Drake and Carl Sagan.
Category. v. t. e. Darwin's finches. Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth. It is also defined as the study of the history of life forms on Earth.