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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 ...
However, viruses are still poorly understood and may have arisen before "life" itself, or may be a more recent phenomenon. Major extinctions in terrestrial vertebrates and large amphibians. Earliest examples of armoured dinosaurs. 195 Ma First pterosaurs with specialized feeding (Dorygnathus). First sauropod dinosaurs.
The basic idea was that life was continuously created as a result of chance events. [17] In the 17th century, people began to question spontaneous generation, in works like Thomas Browne's Pseudodoxia Epidemica. His contemporary, Alexander Ross, erroneously rebutted him. [18] [19] In 1665, Robert Hooke published the first drawings of a ...
Prokaryote life, the first form of life, emerges at the very beginning of this eon, in a process known as abiogenesis. The continents of Ur, Vaalbara and Kenorland may have existed around this time. The atmosphere is composed of volcanic and greenhouse gases. Proterozoic: 2,500–538.8 The name of this eon means "early life".
[12] [13] Darwin noted that orchids have complex adaptations to ensure pollination, all derived from basic floral parts. Darwin gained extensive experience as he collected and studied the natural history of life forms from distant places. Through his studies, he formulated the idea that each species had developed from ancestors with similar ...
Research concerning the relationship between the thermodynamic quantity entropy and both the origin and evolution of life began around the turn of the 20th century. In 1910 American historian Henry Adams printed and distributed to university libraries and history professors the small volume A Letter to American Teachers of History proposing a theory of history based on the second law of ...
Rosen's posthumous work Essays on Life Itself (2000) as well as recent monographs [6] [7] by Rosen's student Aloisius Louie have clarified and explained the mathematical content of Rosen's work. Relational biology
Evolutionary thought, the recognition that species change over time and the perceived understanding of how such processes work, has roots in antiquity. With the beginnings of modern biological taxonomy in the late 17th century, two opposed ideas influenced Western biological thinking: essentialism, the belief that every species has essential characteristics that are unalterable, a concept ...