The Berkeley Evolution Site
The Berkeley site has resources that can help students and educators 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 better able to adapt biologically to changing environments do better than those that do not become extinct. Science is about this process of biological evolution.
What is Evolution?
The term "evolution" could have a variety of meanings that are not scientific. For instance it could refer to "progress" and "descent with modifications." Scientifically it refers to a changing the characteristics of living organisms (or species) over time. In biological terms, this change is caused by natural selection and genetic drift.
Evolution is a central tenet of modern biology. It is a concept that has been tested and verified by a myriad of scientific tests. In contrast to other theories in science such as the Copernican theory or the germ theory of disease, the evolution theory is not a discussion of religion or the existence of God.
Early evolutionists, such as Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical characteristics were predetermined to change, in a gradual way, over time. This was referred to as the "Ladder of Nature", or scala Naturae. Charles Lyell first used this term in 1833 in his Principles of Geology.
Darwin presented his theory of evolution in his book On the Origin of Species, written in the early 1800s. It states that all species of organisms have common ancestors that can be traced using fossils and other evidence. This is the modern view of evolution that is supported by numerous lines of research in science, including molecular genetics.
Scientists don't know how organisms evolved, but they are confident that natural selection and genetic drift is responsible for the development of life. People with desirable traits are more likely than others to survive and reproduce. These individuals transmit their genes to the next generation. In time this leads to gradual changes to the gene pool, which eventually create new species and types.
Some scientists also employ the term evolution to refer to large-scale changes in evolutionary processes, such as the formation of a new species from an ancestral species. Others, like population geneticists, define the term "evolution" more broadly by referring to an overall variation in the frequency of alleles 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 evolution. This happens when living systems begin to develop at the micro level, within individual cells, for instance.
The origin of life is one of the major topics in various disciplines, including biology, chemistry, and geology. The origin of life is a subject of interest in science because 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 emerge from nonliving things is known as spontaneous generation or "spontaneous evolution." This was a common belief before Louis Pasteur's research showed that it was impossible for the emergence of life to occur by a purely natural process.
Many scientists believe it is possible to go from nonliving substances to living ones. However, the conditions needed are extremely difficult to reproduce in a laboratory. Researchers investigating the beginnings of life are also interested in understanding the physical properties of the early Earth and other planets.
In addition, the development of life depends on a sequence of very complex chemical reactions that can't be predicted from the fundamental physical laws on their own. These include the reading of long, information-rich molecules (DNA or RNA) into proteins that carry out some function and the replication of these intricate molecules to generate new DNA or sequences of RNA. These chemical reactions are comparable to a chicken-and egg problem: the emergence and development of DNA/RNA, the protein-based cell machinery, is required to begin the process of becoming a living organism. But without life, the chemistry that is required to enable it appears to be working.
Abiogenesis research requires collaboration with researchers from different disciplines. This includes prebiotic scientists, astrobiologists and planet scientists.
Evolutionary Changes
Today, the word evolution is used to describe the general changes in genetic traits over time. These changes could result from the response to environmental pressures as described in the entry on Darwinism (see the entry on Charles Darwin for background), or from natural selection.
This is a method that increases the frequency of genes that offer an advantage in survival over others, resulting in an ongoing change in the overall appearance of a population. The specific mechanisms responsible for these changes in evolutionary process include mutation and reshuffling of genes in sexual reproduction, and also gene flow between populations.
While reshuffling and mutation of genes happen in all organisms and the process by which beneficial mutations are more frequent is referred to as natural selection. This occurs because, as mentioned above those with the advantageous trait are likely to have a higher fertility rate than those without it. This variation in the number of offspring that are produced over many generations can result in a gradual change in the average number of beneficial characteristics in the group.
This is evident in the evolution of various beak shapes for finches from the Galapagos Islands. They have developed these beaks in order they can get food more easily in their new environment. These changes in shape and form can also aid in the creation of new species.
Most of the changes that occur are the result of one mutation, but sometimes, several changes occur at the same time. The majority of these changes could be neutral or even harmful, but a small number may have a positive effect on survival and reproduction with increasing frequency over time. Natural selection is a process that can produce the accumulating changes over time that lead to the creation of a new species.
Some people confuse the notion of evolution with the notion that inherited characteristics can be changed through conscious choice, or through use and abuse, a notion known as soft inheritance. This is a misunderstanding of the nature of evolution and of the actual biological processes that lead to it. It is more accurate to say that evolution is a two-step, independent process that involves the forces of natural selection as well as mutation.
에볼루션 바카라사이트 of Humans
Modern humans (Homo sapiens) evolved from primates - a species of mammals that includes chimpanzees and gorillas and bonobos. Our predecessors walked on two legs, as evidenced by the first fossils. Genetic and biological similarities suggest that we are closely related to chimpanzees. In reality we are the most closely related to the chimpanzees within the Pan genus which includes pygmy chimpanzees and bonobos. The last common human ancestor and chimpanzees was between 8 and 6 million years ago.
In the course of time, humans have developed a variety of characteristics, including bipedalism and the use fire. They also invented advanced tools. It's only within the last 100,000 years that we've developed the majority of our important characteristics. They include language, a large brain, the ability to create and utilize complex tools, as well as the diversity of our culture.
Evolution is when genetic changes allow members of a group to better adapt to their environment. Natural selection is the mechanism that drives this adaptation. Certain characteristics are more desirable than others. The better adaptable are more likely to pass their genes on to the next generation. This is how all species evolve, and it is the foundation of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law says that species that share a common ancestor tend to develop similar traits over time. This is because those characteristics make it easier for them to survive and reproduce in their environments.
Every organism has a DNA molecule that contains the information necessary to direct their growth. The DNA molecule is made up of base pairs that are spirally arranged around phosphate molecules and sugar molecules. The sequence of bases found in each strand determines the phenotype, the distinctive appearance and behavior of an individual. Variations in mutations and reshufflings of the genetic material (known as alleles) during sexual reproduction can cause variation in a group.
Fossils of the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. While there are some differences between them the fossils all support the notion that modern humans first came into existence in Africa. The evidence from fossils and genetics suggests that the first humans left Africa and moved to Asia and Europe.