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
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 ...
Two-million-year-old evidence shows tool-making hominins inhabited grassland environments
Other Sciences / Archaeology & Fossils
Oct 21, 2009 |
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In an article published in the open-access, peer-reviewed journal PLoS ONE on October 21, 2009, Dr Thomas Plummer of Queens College at the City University of New York, Dr Richard Potts of the Smithsonian Institution Nation ...
Evolution axe goes on display
Other Sciences / Archaeology & Fossils
Oct 19, 2009 |
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(PhysOrg.com) -- A flint hand axe that helped reveal the very ancient age of humankind goes on display at the Natural History Museum October 2009.
Are humans still evolving? Absolutely, says new analysis of long-term survey of human health
Oct 19, 2009 |
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Although advances in medical care have improved standards of living over time, humans aren't entirely sheltered from the forces of natural selection, a new study shows.
Misuse of antibiotics not the only cause of resistance says report
Oct 15, 2009 |
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The perception that antibiotic resistance is primarily the undesirable consequence of antibiotic abuse or misuse is a view that is simplistic and inaccurate, according to a recent report by the American Academy of Microbiology. ...
A Serious Question: Why Do We Laugh?
Other Sciences / Social Sciences
Oct 14, 2009 |
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(PhysOrg.com) -- Not surprisingly, Robert Lynch begins his research paper "It's Funny Because We Think It's True: Laughter is Augmented by Implicit Preferences" with a joke. Not his joke, but one taken from a ...
Science wins fight over evolution in schools, says Case Western Reserve University author
Other Sciences / Social Sciences
Oct 08, 2009 |
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If you want to understand how evolution has challenged the constitutionality of the separation of church and state, Mano Singham from Case Western Reserve University provides a concise and chronological history in his new ...
Homebound Termites Answer 150-Year-Old Evolution Question
Oct 05, 2009 |
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(PhysOrg.com) -- Staying at home may have given the very first termite youngsters the best opportunity to rule the colony when their parents were killed by their neighbors. This is according to new research ...
Using synthetic evolution to study the brain: Researchers model key part of neurons
Oct 02, 2009 |
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The human brain has evolved over millions of years to become a vast network of billions of neurons and synaptic connections. Understanding it is one of humankind's greatest pursuits.
UAB professor's book promises solution for teaching evolution without conflict
Other Sciences / Social Sciences
Sep 30, 2009 |
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University of Alabama at Birmingham (UAB) Associate Professor Lee Meadows, Ph.D., is author of a new book that claims it's possible to teach evolution without offending students who have strong religious convictions against ...
