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The Berkeley Evolution Site Teachers and students who browse the Berkeley site will find resources to help them understand and teach evolution. The resources are organized into different learning paths for example “What does T. rex look like?” Charles Darwin's theory of natural selection explains that over time creatures that are better able to adapt biologically to changing environments thrive, and those that don't become extinct. This process of evolution is the basis of science. What is Evolution? The term “evolution” can have many nonscientific meanings. For instance “progress” or “descent with modification.” Scientifically, it is a term used to describe a changing the characteristics of organisms (or species) over time. This change is based in biological terms on natural selection and drift. Evolution is a central tenet of modern biology. It is a well-supported theory that has withstood the test of time and thousands of scientific studies. Evolution does not deal with spiritual beliefs or God's presence like other theories of science, such as the Copernican or germ theory of diseases. Early evolutionists like Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to evolve in a gradual manner over time. They called this the “Ladder of Nature” or scala naturae. Charles Lyell first used this term in 1833 in his Principles of Geology. Darwin revealed his theory of evolution in his book On the Origin of Species which was written in the early 1800s. It states that all species of organisms have a common ancestry, which can be traced through fossils and other lines of evidence. This is the current perspective on evolution, which is supported in many areas of science which include molecular biology. While scientists do not know the exact mechanism by which organisms evolved however they are sure that the evolution of life on earth is a result of natural selection and genetic drift. People with traits that are advantageous are more likely to survive and reproduce, and they transmit their genes to the next generation. As time passes, this results in a gradual accumulation of changes to the gene pool, which eventually lead to new species and types. Some scientists employ the term”evolution” to refer to large-scale change, such as the formation of a species from an ancestral one. Other scientists, such as population geneticists, define evolution more broadly by referring a net change in the frequency of alleles across generations. Both definitions are acceptable and precise, although some scientists argue that the allele-frequency definition is missing crucial aspects of the evolutionary process. Origins of Life The emergence of life is a crucial step in evolution. This occurs when living systems begin to evolve at a micro-level – within individual cells, for example. The origins of life are an important issue in a variety of disciplines that include biology and the field of chemistry. The question of how living organisms began 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.” The notion that life could emerge from non-living things was called “spontaneous generation” or “spontaneous evolutionary”. This was a common belief prior to Louis Pasteur's tests showed that the creation of living organisms was not possible by a natural process. Many scientists still believe that it is possible to go from nonliving substances to life. However, the conditions that are required are extremely difficult to replicate in the laboratory. This is why researchers studying the nature of life are also interested in understanding the physical properties of the early Earth and other planets. The development of life is also dependent on a series of complex chemical reactions, which are not predicted by the basic physical laws. This includes the conversion of long information-rich molecules (DNA or RNA) into proteins that carry out a function as well as the replication of these intricate molecules to produce new DNA or sequences of RNA. These chemical reactions can be compared with a chicken-and egg problem which is the development and emergence of DNA/RNA, the protein-based cell machinery, is required for the onset life. However, without life, the chemistry required to enable it is working. Abiogenesis research requires collaboration among researchers from different fields. This includes prebiotic chemists planet scientists, astrobiologists, geologists and geophysicists. Evolutionary Changes The word evolution is usually used to refer to the accumulated changes in the genetic characteristics of a population over time. These changes may result from adaptation to environmental pressures, as explained in the article on Darwinism (see the entry on Charles Darwin for background) or may result from natural selection. This is a process that increases the frequency of genes in a species which confer an advantage in survival over other species which results in a gradual change in the appearance of a population. These evolutionary changes are triggered by mutations, reshuffling genes during sexual reproduction, and gene flow. 에볼루션 바카라 무료체험 is the process that makes beneficial mutations more common. All organisms undergo changes and reshuffles of genes. As noted above, individuals who have the advantageous trait have a higher reproductive rate than those who don't. This difference in the number of offspring produced over a long period of time can result in a gradual shift in the average number of beneficial characteristics in the group. This is evident in the evolution of different beak shapes for finches from the Galapagos Islands. They have developed these beaks so they can get food more easily in their new environment. These changes in the form and shape of organisms can also aid in the creation of new species. The majority of the changes that occur are the result of a single mutation, but occasionally several will happen at once. Most of these changes are neither harmful nor even harmful to the organism however, a small proportion of them can be beneficial to the longevity and reproduction of the species, thus increasing their frequency in the population over time. Natural selection is a mechanism that causes the accumulating change over time that eventually leads to a new species. Many people confuse the concept of evolution with the idea that inherited characteristics can be changed through conscious choice or by use and abuse, which is called soft inheritance. This is a misunderstanding of the biological processes that lead up to the process of evolution. A more accurate description of evolution is that it is a two-step procedure involving the independent and often antagonistic forces of natural selection and mutation. Origins of Humans Modern humans (Homo Sapiens) evolved from primates, a group of mammal species that includes chimpanzees and gorillas. Our ancestral ancestors were walking on two legs, as evidenced by the earliest fossils. Genetic and biological similarities suggest that we share an intimate relationship with Chimpanzees. In actual fact, we are most closely with chimpanzees in the Pan genus that includes pygmy and pygmy chimpanzees and bonobos. The last common human ancestor as well as chimpanzees was between 8 and 6 million years ago. Humans have developed a range of traits throughout time such as bipedalism, use of fire, and the development of advanced tools. However, it is only in the last 100,000 years or so that the majority of the traits that distinguish us from other species have developed. These include language, a large brain, the ability to create and utilize sophisticated tools, and a cultural diversity. The process of evolution occurs when genetic changes allow members of the group to better adapt to their environment. Natural selection is the process that drives this adaptation. Certain characteristics are more desirable than others. Those with the better adaptations are more likely to pass their genes to the next generation. This is the way that all species evolve, and it is the basis of the theory of evolution. Scientists call this the “law of natural selection.” The law says that species that share a common ancestor tend to develop similar characteristics over time. This is because these characteristics make it easier for them to live and reproduce in their environment. All organisms have DNA molecules, which contains the information needed to guide their growth and development. The DNA molecule consists of base pairs arranged spirally around phosphate molecules and sugar molecules. The sequence of bases within each strand determines the phenotype which is the person's distinctive appearance and behavior. Different mutations and reshufflings of the genetic material (known as alleles) during reproduction causes variations in a population. Fossils from the earliest human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia, and Europe. Despite some differences they all support the hypothesis that modern humans first came into existence in Africa. The fossil evidence and genetic evidence suggest that early humans came from Africa into Asia and then Europe.