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The Berkeley Evolution Site Students and teachers who explore the Berkeley site will find resources to aid in understanding and teaching evolution. The materials are organized into a variety of learning paths such as “What did T. rex taste like?” Charles Darwin's theory of natural selection explains how in time, creatures better able to adapt biologically to changing environments survive and those that do not become extinct. Science is about this process of evolutionary change. What is Evolution? The term “evolution” can have a variety of meanings that are not scientific. For instance, it can mean “progress” and “descent with modifications.” It is an academic term that refers to the process of change of traits over time in organisms or species. This change is based in biological terms on natural selection and drift. Evolution is the central tenet of modern biology. It is a well-supported theory that has stood up to the test of time and thousands of scientific tests. It does not address God's presence or spiritual beliefs like other theories in science, like the Copernican or germ theory of diseases. 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 way, over time. This was called the “Ladder of Nature”, or scala Naturae. Charles Lyell used the term to describe this idea 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 claims that different species of organisms share the same ancestry, which can be proven through fossils and other evidence. This is the modern view of evolution that is supported by a variety of lines of scientific research that include molecular genetics. Scientists don't know how organisms have evolved, but they are confident that natural selection and genetic drift are the reason for the development of life. Individuals with advantageous characteristics are more likely than others to survive and reproduce. These individuals pass on their genes to the next generation. As time passes the gene pool gradually changes and evolves into new species. Some scientists also use the term”evolution” to refer to large-scale evolutionary changes, such as the formation of an entirely new species from an ancestral species. Certain scientists, including population geneticists, define 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 correct and acceptable, but certain scientists argue that allele frequency definitions omit important features of evolution. Origins of Life One of the most crucial steps in evolution is the appearance of life. This occurs when living systems begin to develop at the micro level – within cells, for example. The origins of life are an important issue in a variety of disciplines such as biology and chemical. The origin of life is a subject of interest in science because it challenges the theory of evolution. It is sometimes referred to as “the mystery” of life or “abiogenesis.” The notion that life could arise from non-living things was called “spontaneous generation” or “spontaneous evolutionary”. It was a popular belief prior to Louis Pasteur's experiments proved that the creation of living organisms was not possible by a natural process. Many scientists still believe it is possible to go from nonliving substances to living. The conditions needed to create life are difficult to reproduce in a lab. This is why researchers investigating the origins of life are also interested in determining the physical properties of early Earth and other planets. The life-cycle of a living organism is dependent on a variety of complex chemical reactions which cannot be predicted by simple physical laws. These include the transformation 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 are often compared to the chicken-and-egg problem of how life first appeared: The appearance of DNA/RNA and protein-based cell machinery is essential for the beginning of life, but without the development of life, the chemical reaction that is the basis for it does not appear to work. Abiogenesis research requires collaboration between scientists from various fields. This includes prebiotic chemists, the astrobiologists, the planet scientists geophysicists and geologists. Evolutionary Changes The term “evolution” is typically used to describe the accumulated changes in the genetic characteristics of a population over time. These changes could be the result of the adaptation to environmental pressures as explained in Darwinism. 에볼루션 룰렛 increases the frequency of genes that provide a survival advantage in a species, resulting in an overall change in the appearance of a group. These changes in evolutionary patterns are caused by mutations, reshuffling genes during sexual reproduction and gene flow. While reshuffling and mutation of genes occur in all living things and the process by which beneficial mutations are more frequent is known as natural selection. This is because, as mentioned above those with the advantageous trait are likely to have a higher reproductive rate than those who do not have it. Over many generations, this differential in the number of offspring born could result in an inclination towards a shift in the number of advantageous traits in a population. This is evident in the evolution of various beak designs on finches that are found in the Galapagos Islands. They have created these beaks to ensure that they can access food more quickly in their new home. These changes in the form and shape of organisms could also help create new species. The majority of changes are caused by a single mutation, however sometimes multiple occur at the same time. Most of these changes are not harmful or even detrimental to the organism, but a small percentage can be beneficial to the survival of the organism and its reproduction, thereby increasing their frequency 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 think that evolution is a form of soft inheritance that is the belief that inherited traits can be changed through deliberate choice or misuse. This is a misunderstood understanding of the nature of evolution and of the actual biological processes that trigger it. It is more accurate to say that evolution is a two-step independent process that involves the forces of natural selection as well as mutation. Origins of Humans Modern humans (Homo Sapiens) evolved from primates, which is a group of mammal species which includes chimpanzees and gorillas. Our ancestral ancestors were walking on two legs, as shown by the oldest fossils. Genetic and biological similarities suggest that we are closely related to Chimpanzees. In actual fact, we are most closely connected to chimpanzees belonging to the Pan Genus that includes pygmy and bonobos and pygmy-chimpanzees. The last common ancestor of humans and chimpanzees was 8 to 6 million years old. As time has passed humans have developed a number of characteristics, such as bipedalism and the use fire. They also invented advanced tools. It is only in the past 100,000 years or so that the majority of the traits that distinguish us from other species have developed. These include a big brain that is complex human ability to construct and use tools, as well as cultural diversity. Evolution occurs when genetic changes allow members of a group to better adapt to the environment. Natural selection is the mechanism that drives this adaptation. Certain traits are preferred over others. People with better adaptations are more likely to pass their genes to the next generation. This is how all species evolve, and it is the basis of the theory of evolution. Scientists call it the “law of natural selection.” The law states species that have a common ancestor are likely to develop similar characteristics as time passes. This is because these traits allow them to survive and reproduce in their natural environment. Every organism has DNA molecules, which is the source of information that helps guide their growth and development. The DNA molecule consists of base pairs that are arranged in a spiral around sugar molecules and phosphate molecules. The sequence of bases in each strand determines the phenotype – 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 population. Fossils from the earliest human species Homo erectus, and Homo neanderthalensis have been discovered in Africa, Asia and Europe. These fossils, despite differences in their appearance, all support the hypothesis of modern humans' origins in Africa. Evidence from fossils and genetics suggest that early humans came out of Africa into Asia and then Europe.