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The Berkeley Evolution Site Teachers and students who browse the Berkeley site will find resources to aid in understanding and teaching evolution. The resources are arranged into different learning paths such as “What did T. rex taste like?” Charles Darwin's theory on natural selection describes how species that are better equipped to adapt to changes in their environments over time, and those that don't end up becoming extinct. Science is about this process of evolution. What is Evolution? The term “evolution” can be used to refer to a variety of nonscientific meanings. For instance, it can mean “progress” and “descent with modifications.” It is a scientific term that is used to describe the process of change of characteristics over time in organisms or species. In terms of biology the change is caused by natural selection and genetic drift. Evolution is one of the fundamental tenets of modern biology. It is a concept that has been proven by a myriad of scientific tests. Evolution does not deal with God's presence or spiritual beliefs in the same way as other theories of science, such as the Copernican or germ theory of diseases. Early evolutionists such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to change in a step-like fashion over time. They referred to this as the “Ladder of Nature” or the scala naturae. Charles Lyell first used this term in 1833 in his Principles of Geology. 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 an ancestry that can be proven through fossils and other lines of evidence. This is the modern view of evolution, which is supported by numerous lines of research in science which includes molecular genetics. While scientists don't know the exact mechanism by which organisms evolved, they are confident that the evolution of life on earth is the result of natural selection and genetic drift. People with advantages are more likely to live and reproduce. They then pass their genes to the next generation. As time passes the gene pool slowly changes and develops into new species. Some scientists also employ the term evolution to refer to large-scale evolutionary changes, such as the formation of the new species from an ancestral species. Some scientists, like population geneticists, define the term “evolution” in a broader sense by talking about the net variation in the frequency of alleles over generations. Both definitions are acceptable and accurate however some scientists believe that the definition of allele frequency is lacking important features of the evolutionary process. Origins of Life A key step in evolution is the appearance of life. The beginning of life takes place when living systems begin to develop at a micro level, such as within cells. The origins of life are an issue in a variety of disciplines, including geology, chemistry, biology and chemistry. The question of how living organisms began is of particular importance in science because it is an important challenge to the theory of evolution. It is often called “the mystery of life” or “abiogenesis.” Traditionally, the notion that life can arise from nonliving things is called spontaneous generation, or “spontaneous evolution.” This was a popular belief prior to Louis Pasteur's experiments showed that it was impossible for the creation of life to happen through a purely natural process. Many scientists believe it is possible to go from living to nonliving substances. The conditions necessary for the creation of life are difficult to replicate in a laboratory. Researchers who are interested in the origins and development of life are also eager to know the physical properties of the early Earth as well as other planets. The development of life is dependent on a number of complex chemical reactions that are not predicted by basic physical laws. These include the reading and re-reading of complex molecules, such as DNA or RNA, to create proteins that perform a particular function. These chemical reactions are often compared to the chicken-and-egg dilemma of how life came into existence in the first place. The emergence of DNA/RNA and protein-based cell machinery is essential for the onset of life, however, without the emergence of life the chemical reaction that is the basis for it does not appear to work. Abiogenesis research requires collaboration with researchers from different fields. This includes prebiotic chemists planet scientists, astrobiologists geophysicists and geologists. Evolutionary Changes The term “evolution” is typically used today to describe the accumulated changes in genetic characteristics of a population over time. These changes can result from adaptation to environmental pressures, as discussed in the entry on Darwinism (see the entry on Charles Darwin for background) or natural selection. This mechanism also increases the frequency of genes that provide the advantage of survival for a species, resulting in an overall change in the appearance of the group. The specific mechanisms responsible for these evolutionary changes are mutation, reshuffling of genes during sexual reproduction, and also gene flow between populations. Natural selection is the process that makes beneficial mutations more common. All organisms undergo changes and reshuffles of their genes. This is because, as noted above those with the beneficial trait tend to have a higher reproductive rate than those without it. Over the course of many generations, this difference in the number of offspring produced can result in a gradual shift in the average number of advantageous traits in a population. This is evident in the evolution of various beak shapes for finches from the Galapagos Islands. They have created these beaks to ensure that they can eat more easily in their new habitat. These changes in the shape and appearance of living organisms may also help create new species. Most of the changes that occur are caused by one mutation, however sometimes, several changes occur simultaneously. Most of these changes are not harmful or even detrimental to the organism, however, a small proportion of them can have an advantageous impact on the longevity and reproduction of the species, thus increasing their frequency in the population over time. Natural selection is a mechanism that could result in the accumulation of changes over time that lead to the creation of a new species. Some people confuse the notion of evolution with the notion that the traits inherited from parents can be altered through conscious choice, or through use and abuse, a notion called soft inheritance. This is a misinterpretation of the nature of evolution and of the actual biological processes that cause it. It is more precise to say that evolution is a two-step, independent process, that is influenced by the forces of natural selection and mutation. Origins of Humans Humans of today (Homo Sapiens) evolved from primates, which is a group of mammal species that includes chimpanzees and gorillas. The earliest human fossils indicate that our ancestors were bipeds, walking on two legs. 에볼루션 무료체험 and genetic similarities indicate that we share a close relationship with chimpanzees. In actual fact our closest relatives are the chimpanzees of the Pan genus. This includes pygmy and bonobos. The last common ancestor shared between modern humans and chimpanzees dated 8 to 6 million years old. Humans have evolved a variety of traits over time including bipedalism, the use of fire, and the development of advanced tools. But it's only in the past 100,000 years or so that most of the important characteristics that differentiate us from other species have emerged. These include language, a large brain, the ability to construct and use sophisticated tools, and a cultural diversity. Evolution happens when genetic changes allow individuals of a population to better adapt to their surroundings. This adaptation is driven by natural selection, a process that determines certain traits are favored over other traits. The more adjusted are more likely to pass on their genes to the next generation. This is the process that evolves all species, and it is the basis of the theory of evolution. Scientists call it the “law of Natural Selection.” The law states that species that have a common ancestor are more likely to develop similar traits over time. This is because those traits allow them to live and reproduce in their environment. All organisms possess a DNA molecule that contains the information needed to guide their growth. The DNA molecule consists of base pairs that are arranged in a spiral around phosphate molecules and sugar molecules. The sequence of bases in each strand determines the phenotype – the distinctive appearance and behavior of an individual. The variations in a population are caused by mutations and reshufflings in genetic material (known collectively as alleles). Fossils from the first human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia and Europe. These fossils, despite variations in their appearance, all support the hypothesis of modern humans' origins in Africa. The fossil and genetic evidence suggests that the first humans left Africa and migrated to Asia and Europe.