Related topics: genes , birds , mutations , natural selection
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
Vampires and collisions rejuvenate stars
6 hours ago |
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Stars in globular clusters are generally extremely old, with ages of 12-13 billion years. However, a small fraction of them appear to be significantly younger than the average population and, because they ...
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 ...
Researchers reveal ancient origins of modern opossum
Other Sciences / Archaeology & Fossils
Dec 16, 2009 |
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A University of Florida researcher has co-authored a study tracing the evolution of the modern opossum back to the extinction of the dinosaurs and finding evidence to support North America as the center of ...
Researchers find reproductive germ cells survive and thrive in transplants, even among species
Dec 15, 2009 |
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Reproductive researchers from the University of Pennsylvania and The Children's Hospital of Philadelphia have succeeded in isolating and transplanting pure populations of the immature cells that enable male ...
Scientists suggest certain genes boost chances for distributing variety of traits, drive evolution
Dec 14, 2009 |
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Genes that don't themselves directly affect the inherited characteristics of an organism but leave them increasingly open to variation may be a significant driving force of evolution, say two Johns Hopkins scientists.
Ancient pygmy sea cow discovered
Other Sciences / Archaeology & Fossils
Dec 14, 2009 |
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(PhysOrg.com) -- The discovery of a Middle Eocene (48.6-37.2 million years ago) sea cow fossil by McGill University professor Karen Samonds has culminated in the naming of a new species. This primitive "dugong" ...
Fossils shake dinosaur family tree
Other Sciences / Archaeology & Fossils
Dec 10, 2009 |
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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 ...
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 ...
Earliest toothless bird found
Other Sciences / Archaeology & Fossils
Dec 10, 2009 |
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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 ...
How Did Evolution Begin?
Sep 28, 2009 |
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(PhysOrg.com) -- Life's ability to replicate itself is essential for evolution, yet even the simplest kind of replication requires a relatively complex system. So what kind of non-replicating system might ...
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, ...
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. ...
Robots Reveal Insights into Evolution
Sep 16, 2009 |
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(PhysOrg.com) -- In an ironic twist to our understanding of life, robots may offer a greater degree of realism for studying some of the intricacies of natural selection and evolution than real organisms offer. ...
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 ...
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 ...
