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The Berkeley Evolution Site Teachers and students who visit the Berkeley site will find resources to help them understand and teach evolution. The resources are arranged into different learning paths, such as “What did T. rex taste like?” Charles Darwin's theory of natural selection states that over time creatures that are more able to adapt to changing environments do better than those that are not extinct. This process of evolution is the basis of science. What is Evolution? The word evolution has many nonscientific meanings. For instance “progress” or “descent with modification.” Scientifically it refers to a process of changes in the traits of living organisms (or species) over time. The reason for this change is biological terms on natural drift and selection. Evolution is a key tenet in modern biology. It is a theory that has been proven through 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 spiritual belief or God's existence. Early evolutionists, including Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical traits were predetermined to change in a step-like manner, as time passes. This was referred to as 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 all species of organisms have common ancestors that can be traced by fossils and other evidence. This is the modern view on evolution, which is supported in many disciplines which include molecular biology. While scientists do not know exactly how organisms developed however they are sure that the evolution of life on earth is the 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. Over time the gene pool slowly changes and develops into new species. Some scientists use the term”evolution” to refer to large-scale changes, like the formation of one species from an ancestral one. Certain scientists, such as population geneticists, define the term “evolution” in a more broad sense by using the term “net change” to refer to the change in allele frequency over generations. Both definitions are acceptable and accurate, although some scientists argue that the allele-frequency definition is missing important features of the evolutionary process. Origins of Life A key step in evolution is the development of life. The emergence of life occurs when living systems begin to develop at a microscopic scale, for instance within cells. The origin of life is an important topic in a variety of areas, including biology and the field of 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 often called “the mystery of life” or “abiogenesis.” Traditionally, the notion that life can emerge from nonliving things is known as spontaneous generation, or “spontaneous evolution.” This was a common belief before Louis Pasteur's experiments showed that it was impossible for the emergence of life to happen through an entirely natural process. Many scientists still believe that it is possible to transition from nonliving substances to life. The conditions needed to make life are not easy to replicate in a laboratory. Researchers interested in the origins and development of life are also eager to learn about the physical characteristics of the early Earth as well as other planets. The growth of life is dependent on a number of complex chemical reactions, which are not predicted by basic physical laws. These include the reading of long information-rich molecules (DNA or RNA) into proteins that perform functions as well as the replication of these complex molecules to create new DNA or RNA sequences. These chemical reactions are comparable to a chicken-and egg problem: the emergence and development of DNA/RNA, the protein-based cell machinery, is necessary to begin the process of becoming a living organism. However without life, the chemistry required to enable it appears to be working. Abiogenesis research requires collaboration with scientists from different fields. This includes prebiotic chemists, astrobiologists, planetary scientists geophysicists and geologists. Evolutionary Changes The term “evolution” is typically used to describe the cumulative changes in genetic characteristics of an entire population over time. These changes could be the result of adaptation to environmental pressures as described in Darwinism. This is a process that increases the frequency of those genes that confer a survival advantage over others, resulting in an ongoing change in the overall appearance of a particular population. These evolutionary changes are caused by mutations, reshuffling genes in the process of sexual reproduction, and also by the flow of genes. Natural selection is the process that makes beneficial mutations more common. All organisms undergo changes and reshuffles of their genes. As mentioned above, those who possess the desirable characteristic have a higher reproduction rate than those who do not. Over many generations, this variation in the numbers of offspring born can result in a gradual shift in the average number of advantageous characteristics in a particular population. An excellent example is the increase in beak size 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 home. These changes in shape and form can aid in the creation of new organisms. The majority of changes are caused by one mutation, but sometimes several occur at the same time. The majority of these changes are not harmful or even harmful to the organism however, a small proportion of them can have a positive impact on survival and reproduction, thus increasing their frequency in the population over time. This is the way of natural selection and it can, over time, produce the accumulating changes that ultimately lead to the creation of a new species. Many people mistakenly associate evolution with the concept of soft inheritance that is the belief that inherited traits can be changed through conscious choice or by abuse. This is a misunderstanding of the biological processes that lead to the process of evolution. A more accurate description of evolution is that it is a two-step process that involves the distinct and often conflicting forces of natural selection and mutation. Origins of Humans Modern humans (Homo Sapiens) evolved from primates, which is a group of mammal species which includes gorillas and chimpanzees. The earliest human fossils show that our ancestors were bipeds, walkers with two legs. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In actual fact we are the most closely connected to chimpanzees belonging to the Pan genus, which includes pygmy chimpanzees and bonobos. The last common ancestor of modern humans and chimpanzees was between 8 and 6 million years ago. In the course of time, humans have developed a variety of characteristics, such as bipedalism as well as the use of fire. They also created advanced tools. However, it is only in the past 100,000 years or so that the majority of the essential traits that distinguish us from other species have developed. These include a large, complex brain human ability to create and use tools, as well as cultural variety. Evolution occurs when genetic changes allow individuals of a population to better adapt to their environment. This adaptation is driven by natural selection, a process whereby certain traits are preferred over others. Those with the better adaptations 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 says that species that have a common ancestor are more likely to develop similar traits over time. It is because these traits help them to survive and reproduce within their environment. 에볼루션 코리아 has a DNA molecule, which is the source of information that helps 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 phenotype or the individual's unique appearance and behavior. The variations in a population are caused by reshufflings and mutations of genetic material (known collectively as alleles). Fossils of the first human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. Although there are some differences the fossils all support the notion that modern humans first came into existence in Africa. The fossil evidence and genetic evidence suggest that early humans moved from Africa into Asia and then Europe.