The idea that all life on Earth has a common origin became well established only in the twentieth century. Early ideas on the evolution of life were most clearly expressed by Lamarck, who described the process as one of progression from simpler to more complex and advanced forms (see EVOLUTION...
Such genetic studies lead to other interesting conclusions as well. For example, it appears that the earliest surviving terrestrial life-forms were all adapted to live at high temperatures. Some biologists think that life might actually have begun in locations on our planet that were extremely hot....
This has revived interest in the prospect that terrestrial life originated in an extraterrestrial environment. The idea that life on Earth has an extraterrestrial origin is not controversial. Carbon, nitrogen, oxygen, sulfur, and phosphorus, the chemical elements on which life is based, formed ...
2.2. Hydrothermal origin of life The discovery of thermophilic organisms in association with deep-sea hydrothermal systems in the late 1970s (Corliss et al., 1979) led to a new idea that life might have originated in hydro- thermal systems on the primitive Earth (Takai et al., 2006; ...
"I also think the idea of a 'War of the Worlds' on Mars between life forms that originated there and those that arrived from Earth is a serious possibility," Farmer said. And that prospect, he continued, raises some key questions: Who would win? Is there the possibility for a competitiv...
At the time it was widely agreed that stromatolites were the oldest known lifeforms on Earth which had left a record of its existence. Therefore, if life originated on Earth, this happened sometime between 4.4 billion years ago, when water vapor first liquefied, and3.5 billion years ago. ...
Life may involve certain engineering problems that have only a finite number of possible solutions. Other engineering problems may have a variety of possible solutions, including many that have not been used by any familiar life forms. Our procedure will be to review some of the definitions that...
environmentalism, political andethicalmovement that seeks to improve and protect the quality of the naturalenvironmentthrough changes to environmentally harmfulhumanactivities; through the adoption of forms of political, economic, and social organization that are thought to be necessary for, or at leastcon...
Using tests such as carbon dating, genetic evidence, and fossil records, scientists have gradually charted out a timeline of life on Earth. Great biologists such as Charles Darwin, Louis Pasteur, and Richard Dawkins have pushed forward new theories on how life on Earth originated, developed, and...
flask by introducing an electrical discharge into an atmosphere of water vapor and some simple compounds thought to have been present naturally at the time when life first developed on earth. A more recent theory now widely held is that life originated in a volcanic setting more than 3.5 ...