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The Berkeley Evolution Site Students and teachers who explore the Berkeley site will find resources to help them understand and teach evolution. The resources are organized into optional learning paths, such as “What does T. rex look like?” Charles Darwin's theory of natural selection explains how over time, animals that are better able to adapt biologically to changing environments survive and those that don't become extinct. This process of evolution is the basis of science. What is Evolution? The term “evolution” could be used to refer to a variety of nonscientific meanings. For example, it can mean “progress” and “descent with modifications.” Scientifically it refers to a process of changing the characteristics of organisms (or species) over time. This change is based in biological terms on natural selection and drift. Evolution is an important concept in the field of biology today. It is a well-supported theory that has stood up to the test of time and a multitude of scientific tests. Evolution doesn't deal with the existence of God or religious beliefs like other theories of science, such as 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 evolve in a step-like fashion over time. This was referred to as 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 published in the early 1800s. It states that all species of organisms share a common ancestry, which can be proven through fossils and other lines of evidence. This is the current view on evolution, and is supported in a wide range of areas of science that include molecular biology. Scientists do not know how organisms evolved however they are certain that natural selection and genetic drift are the primary reason for the development of life. People with advantages are more likely to survive and reproduce. They then pass their genes on to the next generation. Over time, this results in a gradual accumulation of changes to the gene pool, which eventually create new species and forms. Certain scientists use the term evolution in reference to large-scale change, such as the development of a species from an ancestral one. Certain scientists, such as population geneticists, define the term “evolution” in a broader sense by referring to the net change in allele frequency over generations. Both definitions are acceptable and accurate however some scientists believe that the allele-frequency definition is missing essential aspects of the evolution process. Origins of Life The emergence of life is a crucial step in the process of evolution. The emergence of life occurs when living systems start to evolve at a micro scale, for instance within cells. The origin of life is an important topic in a variety of areas that include biology and chemical. The question of how living things started is of particular importance in science because it is a major challenge to the theory of evolution. It is often described as “the mystery of life,” or “abiogenesis.” Traditionally, the notion that life can 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 be a result of a purely natural process. Many scientists believe that it is possible to go from nonliving substances to living. However, the conditions required are extremely difficult to reproduce in a laboratory. This is why scientists studying the origins of life are also keen to understand the physical properties of early Earth and other planets. The life-cycle of a living organism is dependent on a number of complex chemical reactions which are not predicted by basic physical laws. These include the reading of long, information-rich molecules (DNA or RNA) into proteins that carry out functions and the replication of these intricate molecules to create new DNA or sequences of RNA. These chemical reactions are often compared to the chicken-and-egg problem of how life began: The development of DNA/RNA as well as proteins-based cell machinery is vital for the beginning of life, but without the development of life, the chemistry that makes it possible is not working. Abiogenesis research requires collaboration among scientists from different fields. This includes prebiotic scientists, astrobiologists, and planetary scientists. Evolutionary Changes The term “evolution” is commonly used to describe the cumulative changes in genetic characteristics of populations over time. These changes can result from adaptation to environmental pressures, as explained in the article on Darwinism (see the entry on Charles Darwin for background) or may result from natural selection. The latter is a mechanism that increases the frequency of genes in a species that offer an advantage in survival over other species, resulting in a gradual change in the overall appearance of a population. These evolutionary changes are triggered by mutations, reshuffling of genes in the process of sexual reproduction, and also by the flow of genes. While reshuffling and mutations of genes happen in all living organisms and the process by which beneficial mutations become more common is referred to as natural selection. As noted above, 에볼루션 무료체험 with the beneficial characteristic have a higher reproduction rate than those who don't. Over the course of many generations, this differential in the number of offspring born could result in gradual changes in the average amount of desirable traits in a population. A good example of this is the increase in beak size on various species of finches on the Galapagos Islands, which have evolved different shaped beaks that allow them to easily access food in their new home. These changes in shape and form could also help create new organisms. Most of the changes that occur are caused by one mutation, however occasionally several will happen at the same time. The majority of these changes could be negative or even harmful, but a small number can have a beneficial impact on survival and reproduction, increasing their frequency as time passes. This is the way of natural selection and it can be a time-consuming process that produces the cumulative changes that eventually lead to an entirely new species. Some people think that evolution is a form of soft inheritance which is the notion that traits inherited from parents can be changed through conscious choice or abuse. This is a misinterpretation 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 is influenced by the forces of natural selection and mutation. Origins of Humans Modern humans (Homo sapiens) evolved from primates, a group of mammals that includes chimpanzees, gorillas, and bonobos. Our ancestral ancestors were walking on two legs, as evidenced by the first fossils. Biological and genetic similarities indicate that we share an intimate relationship with Chimpanzees. In actual fact, we are most closely related to the chimpanzees within the Pan genus which includes bonobos and pygmy chimpanzees. The last common human ancestor as well as chimpanzees was born between 8 and 6 million years ago. In the course of time, humans have developed a variety of characteristics, such as bipedalism and the use fire. They also invented advanced tools. However, it is only in the past 100,000 years or so that the majority of the characteristics that differentiate us from other species have developed. These include a large brain that is complex human ability to build and use tools, as well as cultural diversity. The process of evolution is when genetic changes allow members of the group to better adapt to their environment. This adaptation is triggered by natural selection, which is a process by which certain traits are favored over other traits. 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 foundation of the theory of evolution. Scientists call it the “law of Natural Selection.” The law says that species that have a common ancestor are more likely to develop similar characteristics over time. It is because these traits allow them to live and reproduce in their environment. Every organism has DNA molecules, which is the source of information that helps direct their growth and development. The structure of DNA is composed of base pairs that are arranged in a spiral around phosphate and sugar molecules. The sequence of bases within each strand determines phenotype, or the individual's characteristic appearance and behavior. A variety of mutations and reshufflings of the genetic material (known as alleles) during reproduction causes variations in a population. Fossils from the first human species, Homo erectus, as well as Homo neanderthalensis have been discovered in Africa, Asia and Europe. While there are some differences between them they all support the hypothesis that modern humans first came into existence in Africa. The fossil and genetic evidence suggests that early humans left Africa and moved to Asia and Europe.