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The Berkeley Evolution Site Teachers and students who browse the Berkeley site will find a wealth of resources to assist them in understanding and teaching evolution. The materials are organized into optional learning paths like “What did T. rex taste like?” Charles Darwin's theory of natural selection explains how animals that are better equipped to adapt biologically to a changing environments survive longer and those that don't become extinct. Science is concerned with this process of evolutionary change. 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 changing 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 well-supported theory that has withstood the tests of time and thousands of scientific studies. Evolution doesn't deal with God's presence or spiritual beliefs, unlike many other theories in science, like the Copernican or germ theory of disease. Early evolutionists such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to change in a stepped-like manner over time. They called this the “Ladder of Nature” or scala naturae. Charles Lyell used the term to describe this concept 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 asserts that different species of organisms have a common ancestry, which can be traced through fossils and other evidence. This is the modern view of evolution, which is supported in a wide range of areas of science that include molecular biology. While scientists don't 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 live and reproduce, and these individuals pass their genes on to the next generation. Over time the gene pool gradually changes and develops into new species. Some scientists also use the term”evolution” to refer to large-scale changes in evolutionary processes such as the creation of the new species from an ancestral species. Certain scientists, such as population geneticists, define the term “evolution” in a broader sense by referring to the net variation in the frequency of alleles over generations. Both definitions are valid and reliable however some scientists believe that the allele-frequency definition is missing crucial aspects of the evolutionary process. Origins of Life One of the most crucial steps in evolution is the appearance of life. The emergence of life happens when living systems start to develop at a microscopic scale, for instance within individual cells. The origin of life is an issue in a variety of disciplines such as geology, chemistry, biology and chemistry. The nature of life is a subject that is of immense interest to scientists because it is a challenge to the theory of evolution. It is sometimes referred to “the mystery” of life or “abiogenesis.” The idea that life could emerge from non-living matter was known as “spontaneous generation” or “spontaneous evolutionary”. This was a common belief prior to Louis Pasteur's experiments proved that the emergence of living organisms was not possible through an organic process. Many scientists believe it is possible to transition from living to nonliving substances. The conditions required for the creation of life are difficult to replicate in a laboratory. Researchers who are interested in the origins and evolution of life are also eager to learn about the physical characteristics of the early Earth as well as other planets. Additionally, the evolution of life is dependent on a sequence of very complex chemical reactions that cannot be predicted from the fundamental physical laws on their own. These include the reading and replication of complex molecules, such as DNA or RNA, to produce proteins that perform a specific function. These chemical reactions can be compared with the chicken-and-egg problem that is the emergence and growth of DNA/RNA, a protein-based cell machinery, is necessary for the onset life. Although, without life, the chemistry required to enable it appears to be working. Abiogenesis research requires collaboration between researchers from different disciplines. This includes prebiotic scientists, astrobiologists and planet scientists. Evolutionary Changes The word evolution is usually used to describe the accumulated changes in the genetic traits of populations over time. These changes may be the result of adaptation to environmental pressures as discussed in Darwinism. This process increases the frequency of genes that confer a survival advantage in a species, resulting in an overall change in the appearance of the group. The specific mechanisms that cause these evolutionary changes include mutation or reshuffling genes during sexual reproduction, as well as gene flow between populations. While mutation and reshuffling of genes happen in all living organisms The process through which beneficial mutations become more common is called natural selection. This occurs because, as we've mentioned earlier those with the advantageous trait are likely to have a higher fertility rate than those without it. This difference in the number of offspring produced over a long period of time can result in a gradual change in the number of advantageous traits within a group. One good example is the increase in the size of the beaks on different species of finches in the Galapagos Islands, which have developed beaks with different shapes to enable them to more easily access food in their new home. These changes in form and shape can also aid in the creation of new species. Most of the changes that occur are caused by one mutation, however occasionally several will happen simultaneously. The majority of these changes could be neutral or even harmful, but a small number can have a beneficial impact on the survival of the species and reproduce with increasing frequency over time. Natural selection is a mechanism that can produce the accumulating changes over time that lead to a new species. Many people mistakenly associate evolution with the concept of soft inheritance which is the notion that inherited traits can be altered by conscious choice or abuse. This is a misunderstanding of the biological processes that lead to evolution. It is more accurate to say that evolution is a two-step independent process, that is influenced by the forces of natural selection as well as mutation. Origins of Humans Modern humans (Homo sapiens) evolved from primates – a group of mammals that also includes chimpanzees, gorillas, and bonobos. The earliest human fossils show that our ancestors were bipeds – walkers on two legs. Biological and genetic similarities indicate that we share the same ancestry with chimpanzees. In fact our closest relatives are chimpanzees of the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor between modern humans and chimpanzees dated between 8 and 6 million years old. Humans have evolved a wide range of traits throughout time such as bipedalism, use of fire and advanced tools. It is only within the last 100,000 years that we have developed the majority of our key characteristics. They include a huge brain that is sophisticated human ability to create and use tools, and cultural diversity. The process of evolution occurs when genetic changes enable members of a group to better adapt to their environment. Natural selection is the process that drives this change. 에볼루션 무료체험 are more desirable than others. Those with the better adaptations are more likely to pass their genes to the next generation. This is how all species evolve and forms the basis of the theory of evolution. Scientists call it the “law of Natural Selection.” The law says that species that have a common ancestor, tend to develop similar characteristics over time. This is because the traits allow them to survive and reproduce in their environment. Every organism has a DNA molecule, which contains the information needed to control their growth and development. The DNA structure is made of base pairs arranged in a spiral around sugar and phosphate molecules. The sequence of bases found in each string determines the phenotype or the distinctive appearance and behavior of a person. Variations in changes and reshuffling of genetic material (known as alleles) during sexual reproduction can cause variation in a group. Fossils of the first human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. These fossils, despite a few differences in their appearance all support the theory of modern humans' origins in Africa. The evidence from fossils and genetics suggests that early humans left Africa and moved to Asia and Europe.