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The Berkeley Evolution Site The Berkeley site has resources that can help students and teachers to understand and teach about evolution. The materials are organized in various learning paths that can be used in a variety of ways for example “What does T. rex look like?” Charles Darwin's theory of natural selection explains how over time creatures that are more able to adapt to changing environments do better than those that are not extinct. Science is concerned with this process of biological evolution. What is Evolution? The word evolution has many nonscientific meanings, such as “progress” or “descent with modification.” It is an academic term that refers to the process of change of characteristics over time in organisms or species. In biological terms this change is caused by natural selection and genetic drift. Evolution is a key concept in the field of biology today. It is a theory that has been confirmed by thousands of scientific tests. Contrary to other theories of science like the Copernican theory or the germ theory of disease, the evolution theory does not address issues of religion or the existence of God. Early evolutionists, such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to change in a gradual manner over time. This was referred to as the “Ladder of Nature” or scala naturae. Charles Lyell used the term to describe this idea in his Principles of Geology, first published in 1833. In the early 1800s, Darwin formulated his theory of evolution and published it in his book On the Origin of Species. It states that all species of organisms have common ancestors that can be traced by fossils and other evidence. This is the current view of evolution that is supported by numerous research lines in science that include molecular genetics. While scientists don't know exactly how organisms evolved, they are confident that the evolution of life on earth is the result of natural selection and genetic drift. 에볼루션바카라사이트 with desirable traits are more likely to live and reproduce, and they transmit their genes to the next generation. Over time this leads to a gradual accumulation of changes in the gene pool that gradually lead to new species and forms. Certain scientists also use the term evolution to refer to large-scale evolutionary changes such as the creation of a new species from an ancestral species. Other scientists, like population geneticists, define it more broadly by referring to a net variation in the frequency of alleles over generations. Both definitions are valid and acceptable, however certain scientists argue that allele frequency definitions miss important aspects of the evolutionary process. Origins of Life One of the most crucial steps in evolution is the appearance of life. The beginning of life takes place when living systems begin to evolve at a micro level, like within individual cells. The origin of life is an important topic in a variety of fields, including biology and chemistry. The question of how living things got their start has a special place in science because it is an important challenge to the theory of evolution. It is often described as “the mystery of life” or “abiogenesis.” Traditionally, the notion that life can emerge from nonliving things is called spontaneous generation, or “spontaneous evolution.” This was a common belief before Louis Pasteur's experiments proved that it was impossible for the development of life to be a result of a purely natural process. Many scientists believe it is possible to move from living to nonliving substances. The conditions required for the creation of life are difficult to replicate in a laboratory. This is why researchers investigating the beginnings of life are also keen to understand the physical properties of the early Earth and other planets. The growth of life is dependent on a variety of complex chemical reactions which cannot be predicted by simple physical laws. These include the reading and the replication of complex molecules, like DNA or RNA, in order to make proteins that perform a specific function. These chemical reactions are often compared to the chicken-and-egg issue of how life came into existence with the emergence of DNA/RNA and protein-based cell machinery is crucial to the birth of life, but without the emergence of life, the chemistry that makes it possible isn't working. Research in the field of abiogenesis requires collaboration among scientists from various disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists. Evolutionary Changes The term “evolution” today is used to describe the gradual changes in genetic traits over time. These changes can result from adaptation to environmental pressures, as explained in the article on Darwinism (see the entry on Charles Darwin for background) or natural selection. The latter is a mechanism that increases the frequency of genes that offer an advantage in survival over other species which results in an ongoing change in the overall appearance of a particular population. These evolutionary changes are triggered by mutations, reshuffling genes during sexual reproduction and the flow of genes. While mutation and reshuffling of genes occur in all living things, the process by which beneficial mutations are more frequent is called natural selection. As noted above, individuals who possess the desirable trait have a higher reproduction rate than those who don't. Over many generations, this differential in the number of offspring born can result in gradual changes in the number of advantageous characteristics in a particular population. One good example is the growing the size of the beaks on different species of finches found on the Galapagos Islands, which have evolved different shaped beaks that allow them to easily access food in their new environment. These changes in the shape and appearance of organisms could also help create new species. Most of the changes that take place are caused by one mutation, however occasionally several will happen simultaneously. Most of these changes can be harmful or neutral, but a small number can have a beneficial impact on survival and reproduction, increasing their frequency as time passes. Natural selection is a mechanism that could result in the accumulation of change over time that eventually leads to a new species. Some people confuse the notion of evolution with the notion that traits inherited can be changed through conscious choice or by use and abuse, a notion known as soft inheritance. This is a misunderstanding of the nature of evolution, and of the actual biological processes that lead to it. It is more accurate to say that evolution is a two-step, separate process, that is influenced by the forces of natural selection and mutation. Origins of Humans Modern humans (Homo Sapiens) evolved from primates, a group of mammal species that includes gorillas and chimpanzees. The earliest human fossils show that our ancestors were bipeds – walkers on two legs. Genetic and biological similarities suggest that we have the same ancestry with Chimpanzees. In actual fact our closest relatives are chimpanzees of the Pan genus. This includes pygmy as well as bonobos. The last common human ancestor and chimpanzees lived between 8 and 6 million years ago. Humans have evolved a variety of traits over time such as bipedalism, use of fire, and the development of advanced tools. It's only in the last 100,000 years that we have developed the majority of our important characteristics. These include a large brain that is sophisticated human ability to construct and use tools, and cultural variety. Evolution occurs when genetic changes allow individuals of a population to better adapt to their surroundings. This adaptation is triggered by natural selection, a process whereby certain traits are more desirable than others. The ones who are better adapted are more likely to pass on their genes to the next generation. This is the way all species evolve, and the basis for the theory of evolution. Scientists call this the “law of natural selection.” The law states species that have an ancestor in common will tend to develop similar traits in the course of time. This is because these traits help them to live and reproduce in their environment. Every living thing has DNA molecules, which is the source of information that helps guide their growth and development. The DNA molecule is made up of base pairs arranged spirally around sugar molecules and phosphate molecules. The sequence of bases in each string determines the phenotype or the distinctive appearance and behavior of a person. A variety of changes and reshuffling of genetic material (known as alleles) during sexual reproduction cause variation in a population. Fossils of the earliest human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. Despite some differences the fossils all support the idea that modern humans first appeared in Africa. The genetic and fossil evidence suggests that the first humans left Africa and moved to Asia and Europe.