The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find a wealth of resources to help them understand and teach evolution. The resources are arranged into different learning paths such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains that over time creatures that are more able to adapt to changing environments do better than those that don't become extinct. Science is concerned with this process of evolution.
What is Evolution?
The term "evolution" can have many nonscientific meanings, including "progress" or "descent with modification." It is scientifically based and is used to describe the process of change of characteristics in a species or species. In biological terms this change is caused by natural selection and genetic drift.
Evolution is a central tenet of modern biology. It is a theory that has been verified by thousands of scientific tests. Evolution does not deal with God's presence or spiritual beliefs like other theories of science, such as the Copernican or germ theory of diseases.
Early evolutionists like Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to change in a step-like fashion over time. This was called 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 presented his theory of evolution in his book On the Origin of Species published in the early 1800s. It states that all species of organisms have an ancestry that can be traced using fossils and other evidence. This is the current understanding of evolution, which is supported by many lines of research in science, including molecular genetics.
While scientists do not know the exact mechanism by which organisms evolved 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 to survive and reproduce, and they pass their genes on to the next generation. As time passes the gene pool gradually changes and develops into new species.
Some scientists use the term"evolution" to refer to large-scale changes, like the evolution of an animal from an ancestral one. Certain scientists, such as population geneticists, define the term "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 accurate and acceptable, however some scientists believe that allele-frequency definitions omit important features of evolution.
Origins of Life
A key step in evolution is the emergence of life. The beginning of life takes place when living systems start to develop at a micro scale, for instance within cells.
에볼루션 바카라 of life are one of the major topics in various disciplines that include biology, chemistry and geology. The question of how living things started has a special place in science since it poses an enormous challenge to the theory of evolution. It is often described as "the mystery of life" or "abiogenesis."
The idea that life could emerge from non-living objects was referred to as "spontaneous generation" or "spontaneous evolutionary". It was a common belief prior to Louis Pasteur's tests showed that the development of living organisms was not achievable through a natural process.
Many scientists still believe that it is possible to transition from nonliving substances to living. The conditions required to create life are difficult to replicate in a laboratory. Researchers interested in the evolution and origins of life are also eager to know the physical properties of the early Earth as well as other planets.
The growth of life is dependent on a variety of complex chemical reactions, that are not predicted by basic physical laws. These include the reading and the replication of complex molecules, such as DNA or RNA, to produce proteins that serve a specific function. These chemical reactions are often compared with the chicken-and-egg issue of how life began: The emergence of DNA/RNA and proteins-based cell machinery is vital for the beginning of life, however, without the appearance of life, the chemical reaction that is the basis for it isn't working.
Abiogenesis research requires collaboration between researchers from different disciplines. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
The word evolution is usually used to refer to the accumulated changes in genetic characteristics of a population 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 those genes in a species which confer an advantage in survival over other species which results in gradual changes in the appearance of a group. The specific mechanisms responsible for these evolutionary changes are mutation, reshuffling of genes during sexual reproduction, as well as gene flow between populations.
While reshuffling and mutation of genes are common in all living things The process through which beneficial mutations are more frequent is known as natural selection. This occurs because, as we've mentioned earlier those who have the beneficial trait tend to have a higher fertility rate than those with it. Over many generations, this differential in the number of offspring born can result in a gradual shift in the average number of beneficial traits in a population.
An excellent example is the growing beak size on different 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 form and shape can aid in the creation of new organisms.
The majority of the changes that take place are caused by one mutation, however occasionally, multiple mutations occur at once. Most of these changes are neutral or even harmful to the organism, but a small percentage can be beneficial to the longevity and reproduction of the species, thus increasing their frequency in the population over time. This is the way of natural selection and it is able to, over time, produce the gradual changes that eventually result in the creation of a new species.
Some people confuse the idea of evolution with the idea that inherited characteristics can be altered by conscious choice, or through use and abuse, a concept known as soft inheritance. This is a misinterpretation of the biological processes that lead to evolution. It is more accurate to say that evolution is a two-step, separate process, which 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 which includes gorillas and chimpanzees. Our predecessors walked on two legs, as demonstrated by the earliest fossils. Biological and genetic similarities indicate that we share an intimate relationship with the chimpanzees. In actual fact our closest relatives are chimpanzees of the Pan genus. This includes pygmy as well as bonobos. The last common ancestor of modern humans and chimpanzees lived between 8 and 6 million years ago.
Humans have evolved a variety of characteristics over time such as bipedalism, use of fire, and the development of advanced tools. However, it is only in the past 100,000 years or so that most of the essential characteristics that differentiate us from other species have been developed. These include a big, complex brain, the ability of humans to construct and use tools, and the diversity of our culture.
Evolution happens when genetic changes allow individuals of a population to better adapt to their surroundings. Natural selection is the process that triggers this adaptation. Certain traits are preferred over others. The better adjusted are more likely to pass on their genes to the next generation. This is the way all species evolve and is the foundation for the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species that have a common ancestor, tend to develop similar characteristics over time. This is because those traits make it easier for them to live and reproduce in their natural environment.
Every organism has a DNA molecule that contains the information needed to control their growth. The DNA molecule is composed of base pairs that are arranged in a spiral around sugar molecules and phosphate molecules. The sequence of bases in each string determines the phenotype or the appearance and behavior of an individual. Variations in a population are caused by reshufflings and mutations of genetic material (known collectively as alleles).
에볼루션 바카라 from the early human species Homo erectus, as well as Homo neanderthalensis have been found in Africa, Asia and Europe. Despite some differences they all support the idea that modern humans first appeared in Africa. Evidence from fossils and genetics suggest that early humans moved out of Africa into Asia and then Europe.