oxygendance75

The Berkeley Evolution Site The Berkeley site has resources that can assist students and teachers understand and teach evolution. The resources are organized into optional learning paths like “What does T. rex look like?” Charles Darwin's theory of natural selection explains how in time, creatures more able to adapt to changing environments survive and those that are not extinct. This process of evolution in biology is the main focus of science. What is Evolution? The word evolution can 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 changing the characteristics of organisms (or species) over time. This change is based in biological terms on natural selection and drift. Evolution is the central tenet of modern biology. It is a theory that has been tested and confirmed by thousands of scientific tests. It does not address spiritual beliefs or God's presence, unlike many other scientific theories such as the Copernican or germ theory of diseases. Early evolutionists, such as Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical characteristics were predetermined to change in a step-like manner, as time passes. They called this 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 states that all species of organisms share an ancestry that can be traced through fossils and other evidence. This is the modern view of evolution that is supported by numerous lines of research in science that include molecular genetics. Scientists don't know how organisms have evolved but they are sure that natural selection and genetic drift are the primary reason for the evolution of life. Individuals with advantageous characteristics are more likely than others to live and reproduce. They then pass their genes on to the next generation. Over time the gene pool slowly changes and develops into new species. Some 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. Some scientists, like population geneticists, define evolution in a more broad sense by using the term “net change” to refer to the change in the frequency of alleles across generations. Both definitions are correct and acceptable, however certain scientists argue that allele frequency definitions omit important features of evolution. Origins of Life One of the most crucial steps in evolution is the development of life. This happens when living systems begin to develop at the micro level – within individual cells, for example. The origins of life are an issue in a variety of disciplines such as biology, chemistry and geology. The question of how living organisms began has a special place in science due to it being a major challenge to the theory of evolution. It is sometimes referred to “the mystery” of life or “abiogenesis.” The notion that life could be born from non-living objects was referred to as “spontaneous generation” or “spontaneous evolutionary”. This was a popular belief prior to Louis Pasteur's tests showed that the emergence of living organisms was not possible by a natural process. Many scientists still believe that it is possible to make the transition from nonliving materials to living. The conditions needed for the creation of life are difficult to reproduce in a lab. Researchers who are interested in the evolution and origins of life are also keen to know the physical properties of the early Earth as well as other planets. Furthermore, the growth of life depends on a sequence of very complex chemical reactions that cannot be predicted from the fundamental physical laws alone. This includes the conversion of long information-rich molecules (DNA or RNA) into proteins that perform some function, and the replication of these complex molecules to produce new DNA or sequences of RNA. These chemical reactions are often compared with the chicken-and-egg dilemma of how life began with the development of DNA/RNA as well as protein-based cell machinery is essential to the birth of life, but without the emergence of life the chemical process that allows it is not working. Abiogenesis research requires collaboration with scientists from various fields. This includes prebiotic scientists, astrobiologists and planet scientists. Evolutionary Changes The term “evolution” is commonly used to refer to the accumulated changes in the genetic characteristics of an entire population over time. These changes may result from adaptation to environmental pressures as explained in the article on Darwinism (see the entry on Charles Darwin for background), or from natural selection. This is a process that increases the frequency of those genes in a species which confer an advantage in survival over other species and causes an ongoing change in the appearance of a group. These evolutionary changes are caused by mutations, reshuffling of genes in the process of sexual reproduction, and also by the flow of genes. While reshuffling and mutation of genes happen in all living organisms and the process by which beneficial mutations become more common is known as natural selection. This is because, as noted above those who have the beneficial trait tend to have a higher reproduction rate than those without it. This difference in the number of offspring produced over many generations can result in a gradual change in the number of advantageous traits within a group. One good example is the growth of beak size on different species of finches in the Galapagos Islands, which have developed beaks with different shapes to allow them to more easily access food in their new environment. These changes in the shape and form of organisms could also aid in the creation of new species. The majority of changes are caused by one mutation, but sometimes several occur at once. The majority of these changes could be negative or even harmful, but a small number may have a positive effect on the survival of the species and reproduce with increasing frequency as time passes. Natural selection is a process that can produce the accumulating changes over time that lead to a new species. Some people confuse the idea of evolution with the notion that the traits inherited from parents can be altered through conscious choice or use and abuse, which is known as soft inheritance. This is a misinterpretation of the biological processes that lead up to the process of evolution. A more precise description is that evolution is a two-step process involving the independent and often conflicting forces of natural selection and mutation. 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 – walking on two legs. Genetic and biological similarities suggest that we are closely related to Chimpanzees. In reality, our closest relatives are the chimpanzees of the Pan genus. This includes pygmy as well as bonobos. The last common human ancestor as well as chimpanzees was between 8 and 6 million years ago. As time has passed humans have developed a number of characteristics, such as bipedalism and the use of fire. They also invented advanced tools. It's only within the last 100,000 years that we have developed the majority of our important characteristics. They include language, a large brain, the capacity to construct and use sophisticated tools, and a the ability to adapt to cultural differences. Evolution happens when genetic changes allow members of a population to better adapt to their environment. Natural selection is the process that triggers this adaptation. Certain traits are preferred over others. The ones who are better adjusted are more likely to pass their genes on to the next generation. This is how all species evolve, and it is the basis of the theory of evolution. Scientists refer to it as the “law of natural selection.” The law says that species that have a common ancestor are more likely to develop similar traits over time. This is because these traits make it easier to survive and reproduce within their environment. All organisms have a DNA molecule that contains the information needed to guide their growth and development. The DNA structure is made of base pairs which are arranged in a spiral, around phosphate and sugar molecules. The sequence of bases within each strand determines the phenotype which is the person's distinctive appearance and behavior. Different changes and reshuffling of genetic material (known as alleles) during sexual reproduction can cause variations in a population. 에볼루션 블랙잭 from the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. Although there are some differences the fossils all support the notion that modern humans first appeared in Africa. The evidence from fossils and genetics suggests that early humans left Africa and moved to Asia and Europe.