brokertuna55

The Berkeley Evolution Site Teachers and students who browse the Berkeley site will find resources to assist them in understanding and teaching evolution. The materials are organized in optional learning paths like “What does T. rex look like?” Charles Darwin's theory of natural selection states that over time creatures that are more adaptable to changing environments do better than those that don't become extinct. This process of evolution is what science is all about. What is Evolution? The term “evolution” 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 changing characteristics in a species or species. The reason for this change is biological terms on natural drift and selection. Evolution is the central tenet of modern biology. It is a well-supported theory that has withstood the test of time and thousands of scientific experiments. In contrast to other theories in science such as the Copernican theory or the germ theory of disease, the evolution theory does not address questions of religious belief or God's existence. Early evolutionists like Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to change in a gradual manner over time. This was known as the “Ladder of Nature” or 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 claims that different species of organisms have an ancestry that can be determined through fossils and other lines of evidence. This is the modern view of evolution, and is supported by many lines of scientific research that include molecular genetics. Scientists don't know how organisms have evolved, but they are confident that natural selection and genetic drift is the primary reason for the evolution of life. Individuals with advantageous traits are more likely to survive and reproduce, and these individuals transmit their genes to the next generation. As time passes the gene pool gradually changes and evolves into new species. Some scientists use the term”evolution” in reference to large-scale change, such as the evolution of a species from an ancestral one. Some scientists, like population geneticists, define evolution in a broad sense, referring to the net change in the frequency of alleles across generations. Both definitions are valid and acceptable, but some scientists believe that allele-frequency definitions do not include important aspects of evolutionary process. Origins of Life The most important step in evolution is the development of life. This occurs when living systems begin to develop at the micro level, within cells, for instance. The origin of life is an important subject in many areas such as biology and chemistry. The nature of life is a topic of great interest in science, as it is a challenge to the theory of evolution. It is sometimes referred to “the mystery” of life or “abiogenesis.” Traditionally, the belief that life can arise from nonliving things is called spontaneous generation or “spontaneous evolution.” This was a common belief before Louis Pasteur's experiments showed that it was impossible for the creation of life to be a result of an entirely natural process. Many scientists still believe it is possible to make the transition from nonliving materials to living. The conditions needed to create life are difficult to replicate in a laboratory. Researchers interested in the origins and evolution of life are also keen to learn about the physical characteristics of the early Earth as well as other planets. Furthermore, the growth of life is dependent on an intricate sequence of chemical reactions that can't be predicted from the fundamental physical laws on their own. These include the transformation of long information-rich molecules (DNA or RNA) into proteins that carry out functions, and the replication of these intricate molecules to produce new DNA or sequences of RNA. These chemical reactions can be compared with the chicken-and-egg problem that is the emergence and growth of DNA/RNA, a protein-based cell machinery, is necessary for the beginning of life. But without life, the chemistry needed to enable it does appear to work. Abiogenesis research requires collaboration with scientists from different fields. This includes prebiotic chemists, planet scientists, astrobiologists geophysicists and geologists. Evolutionary Changes The term “evolution” is typically used to describe the accumulated changes in the genetic traits of populations over time. These changes could result from adaptation to environmental pressures as discussed in the entry on Darwinism (see the entry on Charles Darwin for background) or natural selection. This is a method that increases the frequency of genes in a species that offer an advantage in survival over others and causes a gradual change in the appearance of a group. The specific mechanisms responsible for these evolutionary changes include mutation, reshuffling of genes during sexual reproduction, as well as gene flow between populations. While reshuffling and mutation of genes occur in all living things and the process by which beneficial mutations are more prevalent is known as natural selection. As previously mentioned, those with the beneficial characteristic have a higher reproduction rate than those who don't. Over the course of many generations, this difference in the number of offspring produced can result in a gradual shift in the average number of beneficial characteristics in a particular population. An excellent example is the growing the size of the beaks on different species of finches in the Galapagos Islands, which have developed different beak shapes to allow them to more easily access food in their new home. These changes in the form and shape of organisms could also be a catalyst for the creation of new species. The majority of the changes that occur are the result of one mutation, but sometimes, several changes occur at once. Most of these changes are not harmful or even detrimental to the organism, however a small portion of them could be beneficial to the survival of the organism and its reproduction, thereby increasing their frequency in the population over time. Natural selection is a process that could result in the accumulation of changes over time that lead to a new species. Some people confuse the notion of evolution with the idea that inherited characteristics can be changed through conscious choice or by use and abuse, which is called soft inheritance. This is a misunderstanding of the biological processes that lead to evolution. It is more accurate to say that the process of evolution is a two-step independent process that involves the forces of natural selection as well as mutation. Origins of Humans Humans of today (Homo Sapiens) evolved from primates, a group of mammal species that includes chimpanzees and gorillas. Our ancestral ancestors were walking on two legs, as shown by the oldest fossils. Genetic and biological similarities suggest that we have an intimate relationship with the chimpanzees. In fact, our closest relatives are chimpanzees belonging to the Pan genus. This includes pygmy and bonobos. The last common human ancestor and chimpanzees was born between 8 and 6 million years ago. Over time, humans have developed a variety of characteristics, including bipedalism and the use of fire. They also developed advanced tools. It's only within the last 100,000 years that we have developed the majority of our key traits. They include a huge brain that is sophisticated, the ability of humans to create and use tools, and cultural variety. Evolution occurs when genetic changes allow members of a group to better adapt to the environment. Natural selection is the process that triggers this adaptation. Certain traits are preferred over others. Those with the better adaptations are more likely to pass their genes to the next generation. This is the way that 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 states species that have an ancestor in common will tend to develop similar characteristics in the course of time. our homepage is because these traits allow them to survive and reproduce within their environment. Every living thing has an molecule called DNA that holds the information needed to guide their growth. The DNA molecule consists of base pairs that are arranged in a spiral around sugar molecules and phosphate molecules. The sequence of bases within each strand determines the phenotype, the distinctive appearance and behavior of an individual. Variations in a population can be 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 differences in their appearance all support the theory that modern humans' ancestors originated in Africa. Evidence from fossils and genetics suggest that early humans came out of Africa into Asia and then Europe.