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The Berkeley Evolution Site Teachers and students who browse the Berkeley site will find resources to help them understand and teach evolution. The materials are arranged in optional learning paths, such as “What does T. rex look like?” Charles Darwin's theory of natural selection explains that over time creatures that are more adaptable to changing environments thrive, and those that don't become extinct. Science is about this process of evolution. What is Evolution? The term “evolution” has a variety of nonscientific meanings, such as “progress” or “descent with modification.” Scientifically it refers to a process of changing the characteristics of living organisms (or species) over time. In biological terms the change is based on natural selection and genetic drift. Evolution is a central tenet of modern biology. It is a well-supported theory that has stood up to the test of time and thousands of scientific studies. Unlike many other scientific theories like the Copernican theory or the germ theory of disease, the evolution theory is not a discussion of spiritual belief or the existence of God. 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. They called this 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. In the early 1800s, Darwin formulated his theory of evolution and published it in his book On the Origin of Species. It asserts that different species of organisms share a common ancestry, which can be proven through fossils and other evidence. This is the current view of evolution, which is supported in many scientific fields, including molecular biology. While scientists do not know exactly how organisms developed 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 than others to live and reproduce. They transmit their genes on to the next generation. Over time this leads to a gradual accumulation of changes to the gene pool which gradually result in new species and forms. Certain scientists also use the term”evolution” to refer to large-scale changes in evolutionary processes, such as the formation of the new species from an ancestral species. 에볼루션 무료체험 , like population geneticists, define it more broadly by referring the net variation in the frequency of alleles over generations. Both definitions are acceptable and accurate however, some scientists claim that the definition of allele frequency is lacking important features of the evolutionary process. Origins of Life One of the most crucial steps in evolution is the development of life. The emergence of life occurs when living systems start to develop at a micro scale, for instance within cells. The origin of life is a topic in many disciplines, including biology, chemistry, and geology. The question of how living things got their start is of particular importance in science because it is an enormous challenge to the theory of evolution. It is sometimes referred to as “the mystery” of life or “abiogenesis.” Traditionally, the belief 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 showed that it was impossible for the emergence of life to be a result of a purely natural process. Many scientists still believe it is possible to make the transition from nonliving substances to life. However, the conditions required are extremely difficult to replicate in the laboratory. Researchers studying the origins of life are also interested in determining the physical properties of the early Earth and other planets. The development of life is also dependent on a series of complex chemical reactions which cannot be predicted by simple physical laws. These include the transformation of long, information-rich molecules (DNA or RNA) into proteins that carry out some function and the replication of these intricate molecules to produce new DNA or RNA sequences. These chemical reactions are often compared to the chicken-and-egg issue of how life first appeared: The development of DNA/RNA as well as protein-based cell machinery is essential for the beginning of life, however, without the emergence of life, the chemical reaction that is the basis for it isn't working. Research in the field of abiogenesis requires collaboration among scientists from various disciplines. This includes prebiotic chemists astrobiologists, planetary scientists geophysicists and geologists. Evolutionary Changes The term “evolution” is commonly used today to describe the cumulative changes in the genetic characteristics of an entire population over time. These changes can be the result of adaptation to environmental pressures as discussed in Darwinism. The latter is a mechanism that increases the frequency of genes in a species that confer an advantage in survival over others and causes a gradual change in the appearance of a group. The specific mechanisms that cause these changes in evolutionary process include mutation or reshuffling genes during sexual reproduction, and gene flow between populations. While reshuffling and 에볼루션 코리아 of genes occur in all organisms and the process by which beneficial mutations become more common is referred to as natural selection. This happens because, as we've mentioned earlier those who have the advantageous trait are likely to have a higher reproduction rate than those who do not have it. This differential in the number of offspring produced over a number of generations could cause a gradual change in the number of advantageous traits in the group. This is evident in the evolution of different beak shapes on finches from the Galapagos Islands. They have developed these beaks so that they can access food more quickly in their new home. These changes in the shape and form of organisms can also help create new species. The majority of changes are caused by a single mutation, however sometimes multiple occur at the same time. Most of these changes can be negative or even harmful, but a small number can have a beneficial impact on the survival of the species and reproduce, increasing their frequency as time passes. Natural selection is a process that can produce the accumulating change over time that eventually leads to a new species. Some people confuse the notion of evolution with the notion that the traits inherited from parents can be altered through conscious choice or by use and abuse, a concept called soft inheritance. This is a misunderstanding of the biological processes that lead to evolution. A more precise description is that evolution is a two-step process involving the independent, and often competing, forces of natural selection and mutation. Origins of Humans Humans of today (Homo sapiens) evolved from primates – a species of mammals that also includes gorillas, chimpanzees, and bonobos. The earliest human fossils indicate that our ancestors were bipeds – walkers on two legs. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In actual fact our closest relatives are chimpanzees belonging to the Pan genus. This includes pygmy, as well as bonobos. The last common human ancestor as well as chimpanzees was born between 8 and 6 million years ago. Over time humans have developed a number of characteristics, such as bipedalism as well as the use of fire. They also invented advanced tools. It is only within the last 100,000 years that we have developed the majority of our essential traits. They include a huge, complex brain and the capacity of humans to create and use tools, as well as the diversity of our culture. Evolution occurs when genetic changes allow members of an organization to better adapt to their environment. Natural selection is the process that triggers this adaptation. Certain characteristics are more desirable than others. The better adjusted are more likely to pass their genes on to the next generation. This is the way all species evolve and is the basis for the theory of evolution. Scientists refer to this as the “law of natural selection.” The law states that species that have an ancestor in common will tend to develop similar characteristics over time. It is because these traits allow them to reproduce and survive within their environment. Every living thing has a DNA molecule, which contains the information needed to control their growth and development. The DNA molecule is made up of base pairs that are arranged in a spiral around phosphate molecules and sugar molecules. The sequence of bases within each strand determines phenotype or the individual's unique appearance and behavior. The variations in a population are caused by mutations and reshufflings in 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. These fossils, despite a few variations in their appearance, all support the theory of the origins of modern humans in Africa. The fossil and genetic evidence suggests that early humans left Africa and moved to Asia and Europe.