Evolution
hideIn biology, evolution is change in the genetic material of a population of organisms from one generation to the next. Though changes produced in any one generation are small, differences accumulate with each generation and can, over time, cause substantial changes in the population, a process that can culminate in the emergence of new species. Indeed, the similarities amongst species suggest that all known species are descended from a common ancestor (or ancestral gene pool) through this process of gradual divergence .
The basis of evolution is the genes that are passed on from generation to generation; these produce an organism's inherited traits. These traits vary within populations, with organisms showing heritable differences (variation) in their traits. Evolution itself is the product of two opposing forces: processes that constantly introduce variation, and processes that make variants either become more common or rare. New variation arises in two main ways: either from mutations in genes, or from the transfer of genes between populations and between species. In species that reproduce sexually, new combinations of genes are also produced by genetic recombination, which can increase variation between organisms.
Two major mechanisms determine which variants will become more common or rare in a population. One is natural selection, a process that causes helpful traits (those that increase the chance of survival and reproduction) to become more common in a population and causes harmful traits to become more rare. This occurs because individuals with advantageous traits are more likely to reproduce, meaning that more individuals in the next generation will inherit these traits. Over many generations, adaptations occur through a combination of successive, small, random changes in traits, and natural selection of the variants best-suited for their environment. The other major mechanism driving evolution is genetic drift, an independent process that produces random changes in the frequency of traits in a population. Genetic drift results from the role that chance plays in whether a given trait will be passed on as individuals survive and reproduce.
Evolutionary biologists document the fact that evolution occurs, and also develop and test theories that explain its causes. The study of evolutionary biology began in the mid-nineteenth century, when studies of the fossil record and the diversity of living organisms convinced most scientists that species changed over time. However, the mechanism driving these changes remained unclear until the theories of natural selection were independently discovered by Charles Darwin and Alfred Wallace. Darwin's landmark work On the Origin of Species of 1859 brought the new theories of evolution by natural selection to a wide audience. Darwin's work soon led to overwhelming acceptance of evolution among scientists. In the 1930s, Darwinian natural selection was combined with Mendelian inheritance to form the modern evolutionary synthesis, which connected the units of evolution (genes) and the mechanism of evolution (natural selection). This powerful explanatory and predictive theory directs research by constantly raising new questions, and it has become the central organizing principle of modern biology, providing a unifying explanation for the diversity of life on Earth.
For more information about Evolution, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with evolution
Termite creates sustainable monoculture fungus-farming
Nov 20, 2009 |
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(PhysOrg.com) -- Food production of modern human societies is mostly based on large-scale monoculture crops, but it now appears that advanced insect societies have the same practice. Our societies took just ...
PLoS Genetics 2009 maize genome collection
Nov 19, 2009 |
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Maize is an important crop in many countries of the world. It is widely used for human consumption, animal feed, and industrial materials. It also is considered an exemplar plant species for studying domestication, molecular ...
Darwin's mockingbirds DNA research may help species recovery
Nov 18, 2009 |
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(PhysOrg.com) -- New research could help protect the future of a rare bird in the Galapagos Islands that was an inspiration for Darwin’s theory of evolution by natural selection, scientists report in a paper ...
Slowing evolution to stop drug resistance
Nov 16, 2009 |
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Infectious organisms that become resistant to antibiotics are a serious threat to human society. They are also a natural part of evolution. In a new project, researchers at the University of Gothenburg are attempting to find ...
Two Earth-sized bodies with oxygen rich atmospheres found -- but they're stars not planets
Nov 12, 2009 |
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(PhysOrg.com) -- Astrophysicists at the University of Warwick and Kiel University have discovered two earth sized bodies with oxygen rich atmospheres - however there is a bit of a disappointing snag for anyone ...
Why can't chimps speak? Study links evolution of single gene to human capacity for language
Nov 11, 2009 |
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(PhysOrg.com) -- If humans are genetically related to chimps, why did our brains develop the innate ability for language and speech while theirs did not?
NASA's Great Observatories Celebrate International Year of Astronomy
Nov 10, 2009 |
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(PhysOrg.com) -- A never-before-seen view of the turbulent heart of our Milky Way galaxy is being unveiled by NASA on Nov. 10. This event will commemorate the 400 years since Galileo first turned his telescope ...
Ancient penguin DNA raises doubts about accuracy of genetic dating techniques
Nov 10, 2009 |
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Penguins that died 44,000 years ago in Antarctica have provided extraordinary frozen DNA samples that challenge the accuracy of traditional genetic aging measurements, and suggest those approaches have been ...
Book by UC Riverside biologist explains Darwin's 'Origin of Species'
Nov 09, 2009 |
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Many people have tried to read Charles Darwin's "Origin of Species," whose publication celebrates its 150th anniversary this month, but gave up.
Bacteria expect the unexpected: Scientists observe the emergence of a new adaptation strategy
Nov 04, 2009 |
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Organisms ensure the survival of their species by genetically adapting to the environment. If environmental conditions change too rapidly, the extinction of a species may be the consequence. A strategy to ...
Stars Fueled by Dark Matter Could Hold Secrets to the Universe
Nov 03, 2009 |
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(PhysOrg.com) -- The first stars in the universe may have been very different from the stars we see today, yet they may hold clues to understanding some of the mysterious features of the universe. These "dark ...
There's a speed limit to the pace of evolution, biologists say
Nov 02, 2009 |
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Researchers at the University of Pennsylvania have developed a theoretical model that informs the understanding of evolution and determines how quickly an organism will evolve using a catalogue of "evolutionary speed limits." ...
Snail fossils suggest semiarid eastern Canary Islands were wetter 50,000 years ago
Space & Earth / Earth Sciences
Oct 27, 2009 |
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Fossil land snail shells found in ancient soils on the subtropical eastern Canary Islands show that the Spanish archipelago off the northwest coast of Africa has become progressively drier over the past 50,000 years.
Study Shows Time Traveling May Not Increase Computational Power
Oct 22, 2009 |
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(PhysOrg.com) -- For more than 50 years, physicists have been intrigued by the concept of closed time-like curves (CTCs). Because a CTC returns to its starting point, it raises the possibility of traveling backward in time. ...
Ancient 'Lucy' Species Ate A Different Diet Than Previously Thought
Other Sciences / Archaeology & Fossils
Oct 22, 2009 |
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(PhysOrg.com) -- Research examining microscopic marks on the teeth of the "Lucy" species Australopithecus afarensis suggests that the ancient hominid ate a different diet than the tooth enamel, size and sh ...
