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The Berkeley Evolution Site Teachers and students who visit the Berkeley site will find a wealth of 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 over time creatures that are more adaptable to changing environments do better than those that are not extinct. Science is about this process of biological evolutionary change. What is Evolution? The word evolution can have a variety of meanings that are not scientific. For instance, it can mean “progress” and “descent with modifications.” Scientifically, it is a term used to describe a changing the characteristics of living organisms (or species) over time. In terms of biology, this change is based on natural selection and genetic drift. Evolution is a central tenet of modern biology. It is a theory that has been tested and proven by thousands of scientific tests. Evolution does not deal with the existence of God or religious beliefs in the same way as 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 traits were predetermined to evolve in a stepped-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 idea in his Principles of Geology, first published in 1833. Darwin published his theory of evolution in his book On the Origin of Species which was written in the early 1800s. It asserts that all species of organisms have an ancestry that can be traced by fossils and other evidence. This is the current view of evolution, which is supported by a variety of areas of science, including molecular biology. Scientists do not know how organisms evolved, but they are confident that natural selection and genetic drift is responsible for the development of life. People with traits that are advantageous are more likely to survive and reproduce, and they pass their genes on to the next generation. Over time, the gene pool gradually changes and evolves into new species. Some scientists also use the term evolution to refer to large-scale changes in evolutionary processes such as the creation of a new species from an ancestral species. Some scientists, like population geneticists, define evolution in a broad sense, referring to the net change in allele frequency over generations. Both definitions are valid and acceptable, however some scientists argue that allele-frequency definitions miss important aspects of the evolution. Origins of Life The birth of life is an essential step in evolution. This occurs when living systems begin to evolve at a micro-level – within individual cells, for example. The origin of life is an issue in a variety of disciplines such as biology, chemistry and geology. The question of how living things started has a special place in science because it is an important challenge to the theory of evolution. It is often referred to “the mystery” of life or “abiogenesis.” Traditionally, the belief that life can arise from nonliving things is known as spontaneous generation or “spontaneous evolution.” This was a common belief before Louis Pasteur's research showed that it was impossible for the emergence of life to occur by an entirely natural process. Many scientists still believe it is possible to go from nonliving substances to life. However, the conditions required are extremely difficult to reproduce in the laboratory. Researchers studying the nature of life are also interested in determining the physical properties of early Earth and other planets. Furthermore, the growth of life is a sequence of very complex chemical reactions that cannot be predicted from the fundamental physical laws alone. These include the reading and the replication of complex molecules, such as DNA or RNA, to produce proteins that perform a particular function. These chemical reactions are often compared to the chicken-and-egg problem of how life began in the first place. The development of DNA/RNA as well as protein-based cell machinery is essential to the birth of life, however, without the appearance of life, the chemistry that makes it possible is not working. Research in the field of abiogenesis requires collaboration between scientists from a variety of fields. This includes prebiotic chemists the astrobiologists, the planet scientists geophysicists and geologists. Evolutionary Changes The term “evolution” is typically used today to refer to the accumulated changes in the genetic traits of an entire population over time. These changes can be the result of the adaptation to environmental pressures as explained in Darwinism. This is a process that increases the frequency of those genes in a species that offer an advantage in survival over others, resulting in a gradual change in the appearance of a particular population. These changes in evolutionary patterns are caused by mutations, reshuffling genes during sexual reproduction and the flow of genes. While reshuffling and mutations of genes occur in all living organisms, the process by which beneficial mutations are more prevalent is called natural selection. This happens because, as noted above, those individuals with the advantageous trait are likely to have a higher reproduction rate than those without it. This variation in the number of offspring that are produced over a number of generations could result in a gradual shift in the number of advantageous traits in the group. An excellent example is the growth of the size of the beaks on different species of finches in the Galapagos Islands, which have developed different beak shapes to enable them to more easily access food in their new home. These changes in the form and shape of living organisms may also help create new species. The majority of changes are caused by a single mutation, although sometimes multiple occur at once. The majority of these changes are not harmful or even detrimental to the organism, however, a small proportion of them can have a positive impact on survival and reproduction, 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 the notion of evolution with the notion that traits inherited can be changed through conscious choice, or through use and abuse, a concept known as soft inheritance. This is a misinterpretation of the biological processes that lead up to the process of evolution. It is more precise to say that evolution is a two-step, independent process that involves the forces of natural selection as well as mutation. Origins of Humans Humans of today (Homo sapiens) evolved from primates – a species of mammals that includes gorillas, chimpanzees, and bonobos. The earliest human fossils prove that our ancestors were bipeds, walkers with two legs. Biological and genetic similarities indicate that we share an intimate relationship with Chimpanzees. In actual fact our closest relatives are the chimpanzees from the Pan genus. This includes pygmy as well as bonobos. The last common ancestor of modern humans and chimpanzees dated 8 to 6 million years old. Humans have evolved a variety of characteristics over time, including bipedalism, the use of fire, and the development of advanced tools. But it's only in the past 100,000 years or so that most of the characteristics that differentiate us from other species have emerged. They include a huge brain that is sophisticated and the capacity of humans to construct and use tools, as well as cultural diversity. Evolution occurs when genetic changes allow members of a group to better adapt to their environment. Natural selection is the process that drives this adaptation. Certain characteristics are more desirable than others. The ones with the best adaptations are more likely to pass on their genes to the next generation. This is how all species evolve, and the foundation for the theory of evolution. 에볼루션바카라 call it the “law of natural selection.” The law states species that have a common ancestor are likely to develop similar traits as time passes. This is because those traits make it easier for them to live and reproduce in their environments. Every living thing has the DNA molecule, which contains the information necessary to direct their growth. The structure of DNA is composed of base pair that are arranged in a spiral around phosphate and sugar molecules. The sequence of bases within each strand determines phenotype which is the person's distinctive appearance and behavior. Different mutations and reshufflings of the genetic material (known as alleles) during sexual reproduction cause variations 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 variations in their appearance, all support the theory of modern humans' origins in Africa. Evidence from fossils and genetics suggest that early humans migrated from Africa into Asia and then Europe.