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The Berkeley Evolution Site Teachers and students who browse the Berkeley site will find resources to aid in understanding and teaching evolution. The resources are organized into optional 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 adaptable to changing environments survive and those that are not extinct. 에볼루션 사이트 is concerned with the process of biological evolution. What is Evolution? The term “evolution” has a variety of nonscientific meanings. For instance “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 biological terms the change is caused by natural selection and genetic drift. Evolution is an important principle in modern biology. It is a well-supported theory that has withstood the tests 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 such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to change 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. 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 share an ancestry that can be traced using fossils and other evidence. This is the modern view of evolution, which is supported by a variety of research lines in science, including molecular genetics. Scientists don't know how organisms have evolved however they are certain that natural selection and genetic drift is the primary reason for the development of life. People with desirable traits are more likely to survive and reproduce. They pass on their genes on to the next generation. As time passes, the gene pool gradually changes and develops into new species. Some scientists also employ the term evolution to refer to large-scale evolutionary changes like the creation of a new species from an ancestral species. Some scientists, like population geneticists, define evolution in a broader sense by talking about the net change in allele frequency over generations. Both definitions are acceptable and precise, although some scientists argue that the definition of allele frequency is lacking essential aspects of the evolution process. Origins of Life A key step in evolution is the development of life. This happens when living systems begin to develop at the micro level, within cells, for instance. The origins of life are an important subject in a variety of fields such as biology and the field of chemistry. The origin of life is a subject of interest in science because it is a challenge to the theory of evolution. It is sometimes referred to as “the mystery” of life or “abiogenesis.” Traditionally, the idea that life can arise from nonliving things is called spontaneous generation, or “spontaneous evolution.” This was a popular view before Louis Pasteur's experiments proved that it was impossible for the development of life to occur by a purely natural process. Many scientists still believe it is possible to go from nonliving substances to living. However, the conditions required are extremely difficult to replicate in the laboratory. Researchers interested in the origins and evolution of life are also keen to learn about the physical characteristics of the early Earth as well as other planets. The growth of life is dependent on a variety of complex chemical reactions, which are not predicted by basic physical laws. These include the reading and replication of complex molecules, such as DNA or RNA, to produce proteins that serve a specific function. These chemical reactions can be compared to the chicken-and-egg problem that is the emergence and growth of DNA/RNA, the protein-based cell machinery, is essential for the onset life. Although without life, the chemistry needed to make it possible appears to be working. Abiogenesis research requires collaboration among scientists from various disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists. Evolutionary Changes Today, the word evolution is used to describe the cumulative changes in genetic characteristics over time. These changes could be the result of adaptation to environmental pressures as explained in Darwinism. This process increases the frequency of genes that confer the advantage of survival for a species, resulting in an overall change in the appearance of a group. These evolutionary changes are caused by mutations, reshuffling genes during sexual reproduction, and gene flow. While reshuffling and mutation of genes happen in all organisms The process through which beneficial mutations are more prevalent is called natural selection. As previously mentioned, those with the beneficial characteristic have a higher reproduction rate than those that do not. Over many generations, this differential in the number of offspring born can result in gradual changes in the average number of beneficial characteristics in a particular population. This is evident in the evolution of various beak shapes for finches from the Galapagos Islands. They have developed these beaks in order they can get food more easily in their new environment. These changes in shape and form can also aid in the creation of new species. Most of the changes that occur are the result of one mutation, however sometimes, several changes occur simultaneously. The majority of these changes could be harmful or neutral however, a few could have a positive impact on the survival of the species and reproduce, increasing their frequency as time passes. 에볼루션 사이트 is a mechanism that could result in the accumulation of changes over time that lead to a new species. Some people confuse the idea of evolution with the idea that the traits inherited from parents can be changed through conscious choice, or through use and abuse, which is known as soft inheritance. This is a misinterpretation of the biological processes that lead up to evolution. It is more accurate to say that the process of evolution is a two-step, separate process that involves the forces of natural selection and mutation. Origins of Humans Humans of today (Homo Sapiens) evolved from primates, which is a group of mammal species that includes chimpanzees and gorillas. The earliest human fossils show that our ancestors were bipeds – walkers with two legs. Genetic and biological similarities show that we share the same ancestry with 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 human ancestor and chimpanzees was born between 8 and 6 million years ago. Humans have evolved a wide range of characteristics over time, including bipedalism, the use of fire and advanced tools. But it's only in the last 100,000 years or so that most of the important traits that distinguish us from other species have been developed. They include a huge brain that is complex, the ability of humans to construct and use tools, as well as the diversity of our culture. Evolution happens when genetic changes allow members of a population to better adapt to their environment. Natural selection is the mechanism that triggers this adaptation. Certain traits are preferred over others. The ones with the best adaptations are more likely to pass on their genes to the next generation. This is the way all species evolve and the basis for the theory of evolution. Scientists refer to it as the “law of Natural Selection.” The law states that species which have a common ancestor are likely to develop similar characteristics as time passes. This is because these traits allow them to live and reproduce in their environment. Every organism has a DNA molecule that provides the information necessary to direct their growth and development. The DNA molecule consists of base pairs arranged spirally around phosphate molecules and sugar molecules. The sequence of bases found in each strand determines the phenotype – the appearance and behavior of an individual. Variations in mutations and reshufflings of the genetic material (known as alleles) during reproduction causes variation in a group. Fossils of the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. Despite some differences the fossils all support the notion that modern humans first came into existence in Africa. The fossil and genetic evidence suggests that early humans left Africa and migrated to Asia and Europe.