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
Earliest toothless bird found
Other Sciences / Archaeology & Fossils
8 hours ago |
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(PhysOrg.com) -- A new species of bird from the Cretaceous period in China has been identified. It had toothless upper and lower jaws, and provides significant information on the diversification in the evolution ...
Fossils shake dinosaur family tree
Other Sciences / Archaeology & Fossils
3 hours ago |
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(PhysOrg.com) -- Paleontologists have unearthed a previously unknown meat-eating dinosaur in New Mexico, settling a debate about early dinosaur evolution, revealing a period of explosive diversification and ...
Social scientists build case for 'survival of the kindest'
Other Sciences / Social Sciences
Dec 08, 2009 |
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(PhysOrg.com) -- Researchers at the University of California, Berkeley, are challenging long-held beliefs that human beings are wired to be selfish. In a wide range of studies, social scientists are amassing ...
Brains versus brawn: Study finds there's more to the Noisy Miner than just being a backyard bully
Dec 08, 2009 |
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(PhysOrg.com) -- Some consider the Noisy Miner bird a badly-behaved backyard bully - an avian aggressor that moves into the neighbourhood and quickly takes over.
New technology helps scientists understand ancient fossils
Other Sciences / Archaeology & Fossils
Dec 07, 2009 |
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Some of the world's oldest human bones and other ancient relics are studied here using some of the world's newest technologies.
Male and female shopping strategies show evolution at work in the mall
Other Sciences / Social Sciences
Dec 02, 2009 |
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Male and female shopping styles are in our genes---and we can look to evolution for the reason. Daniel Kruger, research faculty at the University of Michigan School of Public Health, says it's perfectly natural that men often ...
Supervolcano eruption -- in Sumatra -- deforested India 73,000 years ago
Space & Earth / Earth Sciences
Nov 23, 2009 |
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A new study provides "incontrovertible evidence" that the volcanic super-eruption of Toba on the island of Sumatra about 73,000 years ago deforested much of central India, some 3,000 miles from the epicenter, ...
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 ...
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 ...
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?
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 ...
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 ...
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 ...
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 ...
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