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The Berkeley Evolution Site The Berkeley site has resources that can help students and teachers to understand and teach about evolution. The resources are organized into a variety of learning paths such as “What did T. rex taste like?” Charles Darwin's theory of natural selection explains that over time creatures that are more adaptable to changing environments survive and those that don't become extinct. Science is about this process of biological evolution. What is Evolution? 에볼루션사이트 can have many nonscientific meanings. For instance it could refer to “progress” and “descent with modifications.” It is scientifically based and refers to the process of change of characteristics in a species or species. This change is based in biological terms on natural drift and selection. Evolution is an important principle in the field of biology today. It is an established theory that has stood the tests of time and thousands of scientific tests. Unlike many other scientific theories like the Copernican theory or the germ theory of disease, the evolution theory does not address issues of religious belief or God's existence. Early evolutionists such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to evolve in a step-like fashion over time. They referred to this as 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 claims that different species of organisms have the same ancestry, which can be traced through fossils and other evidence. This is the current understanding of evolution that is supported by numerous research lines in science that include molecular genetics. While scientists don't know exactly how organisms evolved but they are certain that the evolution of life on earth is the result of natural selection and genetic drift. People with desirable traits are more likely to survive and reproduce, and these individuals pass their genes on to the next generation. As time passes this leads to gradual changes in the gene pool, which eventually create new species and forms. Certain scientists use the term”evolution” in reference to large-scale changes, like the formation 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 acceptable and precise, although some scientists argue that the allele-frequency definition is missing essential aspects of the evolution process. Origins of Life A key step in evolution is the emergence of life. This happens when living systems begin to evolve at a micro-level – within individual cells, for instance. The origins of life is one of the major topics in various disciplines, including biology, chemistry, and geology. The origin of life is a topic that is of immense interest to scientists because it is a challenge to the theory of evolution. It is often referred to “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 popular view before Louis Pasteur's experiments proved that it was impossible for the development of life to be a result of the natural process. Many scientists still believe that it is possible to make the transition from nonliving substances to living. The conditions needed to create life are difficult to replicate in a laboratory. Researchers interested in the evolution and origins of life are also keen to understand the physical properties of the early Earth as well as other planets. The development of life is dependent on a variety of complex chemical reactions that are not predicted by basic physical laws. These include the reading and replication of complex molecules, like DNA or RNA, in order to make proteins that perform a particular function. These chemical reactions are often compared with the chicken-and-egg issue of how life first appeared in the first place. The appearance of DNA/RNA and proteins-based cell machinery is vital for the beginning of life, but without the emergence of life the chemical reaction that is the basis for it isn't working. Abiogenesis research requires collaboration among scientists from various disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists. Evolutionary Changes The word evolution is usually used today to describe the accumulated changes in the genetic characteristics of a population over time. These changes could be the result of adaptation to environmental pressures as explained in Darwinism. This is a method that increases the frequency of genes in a species which confer an advantage in survival over others and causes an ongoing change in the overall appearance of a particular population. The specific mechanisms responsible for these evolutionary changes are mutation or reshuffling genes during sexual reproduction, and also gene flow between populations. While reshuffling and mutation of genes occur in all organisms and the process by which beneficial mutations are more prevalent is called natural selection. This occurs because, as we've mentioned earlier those with the advantageous trait are likely to have a higher reproduction rate than those with it. Over many generations, this difference in the number of offspring born could result in an inclination towards a shift in the number of beneficial 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 shape and form could also help create new organisms. Most of the changes that occur are the result of a single mutation, but occasionally, multiple mutations occur at the same time. Most of these changes are not harmful or even harmful to the organism, however a small portion of them could have a positive impact on survival and reproduction, thus increasing the frequency of these changes in the population over time. This is the mechanism of natural selection and it is able to eventually result in the accumulating changes that eventually lead to the creation of a new species. Some people confuse evolution with the idea of soft inheritance which is the notion that traits inherited from parents can be changed through conscious choice or abuse. This is a misunderstanding of the nature of evolution, and of the actual biological processes that trigger it. A more accurate description of evolution is that it involves a two-step process, which involves the separate, and often competing, forces of mutation and natural selection. Origins of Humans Modern humans (Homo Sapiens) evolved from primates, a species of mammal species that includes gorillas and chimpanzees. The earliest human fossils prove that our ancestors were bipeds. They were walkers with two legs. Biological and genetic similarities indicate that we have the same ancestry 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 was between 8 and 6 million years old. As time has passed, humans have developed a variety of characteristics, including bipedalism and the use of fire. They also developed advanced tools. It is only in the last 100,000 years or so that the majority of the essential traits that distinguish us from other species have developed. These include a big brain that is complex and the capacity of humans to build and use tools, as well as the diversity of our culture. Evolution occurs when genetic changes allow members of the group to better adapt to the environment. This adaptation is driven by natural selection, a process whereby certain traits are more desirable than other traits. The more adapted are more likely to pass on their genes to the next generation. This is the way all species evolve and is the basis for the theory of evolution. Scientists call this the “law of natural selection.” The law states that species which have an ancestor in common will tend to acquire similar traits in the course of time. This is because the characteristics make it easier for them to survive and reproduce in their environment. Every living thing 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 sugar molecules and phosphate molecules. The sequence of bases within each strand determines phenotype which is the person's distinctive appearance and behavior. Variations in a population are caused by mutations and reshufflings of genetic material (known collectively as alleles). Fossils from the earliest human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia, and Europe. Despite some differences the fossils all support the hypothesis that modern humans first appeared in Africa. The fossil and genetic evidence suggests that early humans left Africa and migrated to Asia and Europe.