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The Berkeley Evolution Site Teachers and students who visit the Berkeley site will find a wealth of resources to help them understand and teach evolution. The materials are organized in different learning paths like “What does T. rex look like?” Charles Darwin's theory of natural selection explains how creatures who are better able to adapt to changes in their environments over time, and those who do not become extinct. This process of biological evolution is what science is all about. What is Evolution? The word evolution can have a variety of meanings that are not scientific. For example, it can mean “progress” and “descent with modifications.” It is a scientific term that is used to describe the process of changing characteristics in a species or species. In biological terms the change is caused by natural selection and genetic drift. Evolution is one of the fundamental tenets of modern biology. It is an established theory that has withstood the tests of time and thousands of scientific tests. Evolution doesn't deal with the existence of God or religious beliefs like other scientific theories such as the Copernican or germ theory of disease. Early evolutionists, including Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical characteristics were predetermined to change, in a step-like manner, over time. They referred to this as the “Ladder of Nature” or the scala naturae. Charles Lyell used the term to describe this concept in his Principles of Geology, first published in 1833. Darwin revealed his theory of evolution in his book On the Origin of Species, written in the early 1800s. It claims that different species of organisms have the same ancestry, which can be proven through fossils and other lines of evidence. This is the current perspective on evolution, and is supported in many scientific fields which include molecular biology. Scientists aren't sure how organisms have evolved, but they are confident that natural selection and genetic drift are the primary reason for the development of life. People with desirable traits are more likely to live and reproduce, and they transmit their genes to the next generation. Over time the gene pool slowly changes and evolves into new species. Some scientists also use the term evolution to describe large-scale evolutionary changes such as the creation of an entirely new species from an ancestral species. Certain scientists, such as population geneticists define evolution in a broader sense by referring to the net variation in the frequency of alleles over generations. Both definitions are valid and acceptable, but certain scientists argue that allele frequency definitions do not include important aspects of evolutionary process. 에볼루션게이밍 of Life One of the most crucial steps in evolution is the emergence of life. This happens when living systems begin to evolve at the micro level, within cells, for example. The origin of life is an important issue in many areas that include biology and the field of chemistry. The origin of life is a subject that is of immense interest to scientists because it is a challenge to the theory of evolution. It is often referred to as “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 occur by the natural process. Many scientists still believe it is possible to make the transition from nonliving materials to living. 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 understand the physical properties of the early Earth as well as other planets. The growth of life is dependent on a variety of complex chemical reactions, which cannot be predicted by basic physical laws. These include the reading of long information-rich molecules (DNA or RNA) into proteins that carry out a function as well as the replication of these complex molecules to produce new DNA or RNA sequences. These chemical reactions can be compared to a chicken-and egg problem which is the development and emergence of DNA/RNA, protein-based cell machinery, is required for the onset life. Although without life, the chemistry needed to make it possible is working. Abiogenesis research requires collaboration among scientists from different disciplines. This includes prebiotic chemists astrobiologists, planetary scientists, geologists and geophysicists. Evolutionary Changes The term “evolution” today is used to describe the cumulative changes in genetic characteristics over time. These changes could be the result of adapting to environmental pressures, as explained in Darwinism. This is a process that increases the frequency of genes in a species that confer a survival advantage over others and causes gradual changes in the appearance of a group. The specific mechanisms behind these evolutionary changes include mutation and reshuffling of genes in sexual reproduction, and gene flow between populations. Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo changes and reshuffles of genes. As previously mentioned, those who possess the desirable characteristic have a higher reproduction rate than those who do not. Over many generations, this difference in the numbers of offspring produced can result in an inclination towards a shift in the number of advantageous characteristics in a particular population. This can be seen in the evolution of different beak designs on finches that are found in the Galapagos Islands. They have developed these beaks in order they can get food more quickly in their new home. These changes in shape and form could aid in the creation of new organisms. The majority of changes are caused by a single mutation, however sometimes multiple occur at once. The majority 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 the frequency of these changes in the population over time. Natural selection is a process that causes the accumulating change over time that eventually leads to a new species. Some people confuse evolution with the idea of soft inheritance, which is the idea that traits inherited from parents can be changed by conscious choice or by abuse. This is a misinterpretation of the biological processes that lead to the process of evolution. A more accurate description of evolution is that it involves a two-step process, that involves the distinct and often antagonistic forces of natural selection and mutation. Origins of Humans Humans today (Homo sapiens) evolved from primates, a group of mammals that includes chimpanzees, gorillas, and bonobos. Our ancestral ancestors were walking on two legs, as demonstrated by the earliest fossils. Genetic and biological similarities suggest that we have an intimate relationship with chimpanzees. In reality, our closest relatives are the chimpanzees belonging to the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor shared between humans and chimpanzees was between 8 and 6 million years old. Humans have developed a range of traits over time such as bipedalism, use of fire and advanced tools. It is only in the last 100,000 years or so that most of the important traits that distinguish us from other species have developed. They include language, a large brain, the ability to create and utilize sophisticated tools, and a cultural diversity. Evolution happens when genetic changes allow individuals in a group 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 adapted are more likely to pass on their genes to the next generation. This is the way that all species evolve and forms the foundation of the theory of evolution. Scientists call this the “law of natural selection.” The law states that species which have an ancestor in common will tend to develop similar traits in the course of time. This is because the traits allow them to survive and reproduce in their environment. Every living thing has a DNA molecule, which provides the information necessary to direct their growth and development. The DNA structure is composed of base pair that are arranged in a spiral around sugar and phosphate molecules. The sequence of bases within each string determines the phenotype or the characteristic 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 of the earliest human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia, and Europe. These fossils, despite some variations in their appearance, all support the hypothesis of the origins of modern humans in Africa. Evidence from fossils and genetics suggest that early humans migrated from Africa into Asia and then Europe.