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The Berkeley Evolution Site Students and teachers who explore the Berkeley site will find a wealth of resources to aid in understanding and teaching evolution. The materials are organized in optional learning paths for example “What does T. rex look like?” Charles Darwin's theory of natural selection explains that over time, animals that are more adaptable to changing environments thrive, and those that are not extinct. This process of evolution in biology is what science is all about. What is Evolution? The term “evolution” can have a variety of meanings that are not scientific. For example, it can mean “progress” and “descent with modifications.” Scientifically, it refers to a process of changes in the traits of organisms (or species) over time. In biological terms the change is based on natural selection and genetic drift. Evolution is one of the fundamental tenets of modern biology. It is a theory that has been confirmed by thousands of scientific tests. Contrary to other theories of science, such as the Copernican theory or the germ theory of disease, evolution is not a discussion of religion or God's existence. Early evolutionists, such as Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical traits were predetermined to change, in a gradual manner, as time passes. This was called 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. Darwin published his theory of evolution in his book On the Origin of Species, written in the early 1800s. It states that all species of organisms share an ancestry that can be traced using fossils and other evidence. This is the modern view of evolution that is supported by a variety of lines of scientific research which includes molecular genetics. Scientists aren't sure how organisms have evolved however they are certain that natural selection and genetic drift is the reason for the evolution of life. Individuals with advantageous characteristics are more likely to survive and reproduce. They pass on their genes to the next generation. Over time, the gene pool gradually changes and develops into new species. 에볼루션 게이밍 employ the term”evolution” to refer to large-scale changes, like the evolution of an animal from an ancestral one. Certain scientists, including population geneticists define evolution in a broad sense, talking about the net change in the frequency of alleles across generations. Both definitions are valid and reliable however some scientists believe that the allele-frequency definition omits essential aspects of the evolution process. Origins of Life The birth of life is a key step in evolution. The emergence of life happens when living systems begin to develop at a microscopic level, such as within individual cells. The origins of life is an issue in a variety of disciplines such as biology, chemistry, and geology. The origin of life is a subject that is of immense interest to scientists because it challenges the theory of evolution. It is often referred to as “the mystery of life,” or “abiogenesis.” Traditionally, the belief that life could emerge from nonliving objects is known as spontaneous generation, or “spontaneous evolution.” This was a common belief before Louis Pasteur's experiments proved that it was impossible for the development of life to happen through the natural process. Many scientists still think it is possible to transition from nonliving substances to living ones. However, the conditions that are required are extremely difficult to replicate in a laboratory. Researchers studying the nature of life are also keen to understand the physical properties of the 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 basic physical laws. These include the reading of long information-rich molecules (DNA or RNA) into proteins that perform some function, and the replication of these intricate molecules to create new DNA or RNA sequences. These chemical reactions can be compared with a chicken-and egg problem which is the development and emergence of DNA/RNA, the protein-based cell machinery, is necessary to begin the process of becoming a living organism. But, without life, the chemistry needed to enable it does appear to work. Research in the area of abiogenesis requires collaboration among scientists from various fields. This includes prebiotic scientists, astrobiologists, and planetary scientists. Evolutionary Changes The term “evolution” is used to describe cumulative changes in genetic characteristics over time. These changes may be the result of adapting to environmental pressures, as described in Darwinism. This latter mechanism increases the frequency of genes that confer an advantage for survival in a species, resulting in an overall change in the appearance of an entire group. These evolutionary changes are caused by mutations, reshuffling genes during sexual reproduction and the flow of genes. While mutation and reshuffling of genes happen in all living organisms, the process by which beneficial mutations become more common is known as natural selection. As noted above, individuals who possess the desirable trait have a higher reproductive rate than those who don't. This difference in the number of offspring produced over a long period of time can result in a gradual change in the number of advantageous traits within a group. This is evident in the evolution of different beak designs on finches that are found in the Galapagos Islands. They have developed these beaks so they can get food more easily in their new environment. 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 once. Most of these changes are neutral or even harmful to the organism, however a small portion of them could have a positive impact on survival and reproduction, thus increasing their frequency in the population over time. Natural selection is a process that causes the accumulating change over time that eventually leads to the creation of a new species. Many people confuse evolution with the idea of soft inheritance, which is the idea that traits inherited from parents can be altered by deliberate choice or misuse. This is a misunderstanding of the biological processes that lead to evolution. It is more precise to say that evolution is a two-step, independent process, that is influenced by the 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. The earliest human fossils prove that our ancestors were bipeds – walkers on two legs. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In reality we are the most closely with chimpanzees in the Pan Genus, which includes bonobos and pygmy chimpanzees. The last common ancestor between humans and chimpanzees was 8 to 6 million years old. Humans have evolved a variety of characteristics 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 emerged. These include language, a large brain, the capacity to construct and use complex tools, and the diversity of our culture. The process of evolution occurs when genetic changes allow individuals in a group to better adapt to their environment. Natural selection is the process that drives this adaptation. Certain traits are preferred over others. The ones who are better adapted are more likely to pass their genes on to the next generation. This is how all species evolve and is the foundation for 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 traits in the course of time. It is because these traits help them to survive and reproduce within their environment. Every organism has the DNA molecule, which contains the information necessary to direct their growth. The DNA structure is composed of base pairs that are arranged in a spiral around phosphate and sugar molecules. The sequence of bases within each strand determines the phenotype, the characteristic appearance and behavior of an individual. Variations in changes and reshuffling of genetic material (known as alleles) during reproduction causes variation in a group. Fossils from the early human species Homo erectus, and Homo neanderthalensis have been found in Africa, Asia and Europe. These fossils, despite a few differences in their appearance all support the hypothesis that modern humans' ancestors originated in Africa. The evidence from fossils and genetics suggests that the first humans left Africa and moved to Asia and Europe.