The Berkeley Evolution Site
The Berkeley site has resources that can help students and educators to understand and teach about evolution. The materials are arranged in different 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 able to adapt to changing environments thrive, and those that don't become extinct. Science is all about this process of evolutionary change.
What is Evolution?
The term "evolution" could be used to refer to a variety of nonscientific meanings. For example, it can mean "progress" and "descent with modifications." It is an academic term that is used to describe the process of change of characteristics over time in organisms or species. The reason for this change is biological terms on natural drift and selection.
Evolution is an important principle in modern biology. It is a concept that has been tested and confirmed by a myriad of scientific tests. Contrary to other theories of science such as the Copernican theory or the germ theory of disease, evolution does not address issues of religion or God's existence.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical characteristics were predetermined to change, in a step-wise manner, over time. They called this the "Ladder of Nature" or the 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 asserts that all species of organisms share a common ancestry which can be traced using fossils and other evidence. This is the current perspective on evolution, and is supported by a variety of areas of science, including molecular biology.
Scientists don't know how organisms have evolved however they are certain that natural selection and genetic drift are responsible for the evolution of life. Individuals with advantageous traits are more likely to live and reproduce, and these individuals pass their genes on to the next generation. Over time this leads to gradual changes to the gene pool, which eventually lead to new species and forms.
Certain scientists also use the term"evolution" to refer to large-scale evolutionary changes like the creation of an entirely new species from an ancestral species. Some scientists, like population geneticists define evolution in a broader sense by referring to the net change in the frequency of alleles across generations. Both definitions are accurate and palatable, but some scientists argue that allele-frequency definitions miss important aspects of the evolution.
Origins of Life
The emergence of life is a key step in evolution. The emergence of life occurs when living systems start to develop at a micro level, such as within individual cells.
The origin of life is an important subject in a variety of areas, including biology and chemistry. The origin of life is a subject of interest in science, as it is a challenge to the theory of evolution. It is sometimes referred to as "the mystery" of life or "abiogenesis."
Traditionally, the idea that life can arise from nonliving objects is known as spontaneous generation or "spontaneous evolution." This was a popular view before Louis Pasteur's experiments showed that it was impossible for the creation of life to happen through a purely natural process.
Many scientists believe it is possible to move from nonliving to living substances. The conditions needed for the creation of life are difficult to reproduce in a lab. This is why researchers studying the beginnings of life are also interested in understanding the physical properties of early Earth and other planets.
Furthermore, the growth of life is an intricate sequence of chemical reactions that can't be predicted from basic physical laws alone. These include the reading and replication of complex molecules, such as DNA or RNA, to produce proteins that serve a specific function. These chemical reactions are often compared to the chicken-and-egg issue of how life came into existence: The emergence of DNA/RNA and protein-based cell machinery is essential for the onset of life, however, without the appearance of life, the chemical process that allows it does not appear to work.
Research in the area of abiogenesis requires collaboration among scientists from various fields. This includes prebiotic scientists, astrobiologists and planet scientists.
Evolutionary Changes
The term "evolution" is used to describe the cumulative changes in genetic characteristics 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 from natural selection.
에볼루션카지노 is a mechanism that increases the frequency of those genes in a species that confer an advantage in survival over others which results in an ongoing change in the overall appearance of a particular population. The specific mechanisms responsible for these evolutionary changes are mutation, reshuffling of genes during sexual reproduction, and also gene flow between populations.
While reshuffling and mutations of genes happen in all living organisms, the process by which beneficial mutations become more common is called natural selection. As previously mentioned, those with the beneficial trait have a higher reproduction rate than those who don't. Over the course of many generations, this differential in the numbers of offspring produced can result in a gradual shift in the amount of desirable traits in a population.
An excellent example is the growth of the size of the beaks 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 shape and form can also help create new organisms.
Most of the changes that take place are caused by a single mutation, but occasionally several will happen at once. Most of these changes are neutral or even harmful to the organism but a small percentage can have an advantageous impact on survival and reproduction, thus increasing their frequency in the population over time. Natural selection is a mechanism that can produce the accumulating change over time that eventually leads to a new species.
Many people confuse the concept of evolution with the idea that traits inherited can be changed through conscious choice or use and abuse, a notion called soft inheritance. This is a misinterpretation of the biological processes that lead up to the process of evolution. A more accurate description of evolution is that it is a two-step procedure which involves the separate, and often competing, forces of mutation and natural selection.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, a species of mammal species that includes gorillas and chimpanzees. Our predecessors walked on two legs, as shown by the first fossils. Genetic and biological similarities show that we have an intimate relationship with the chimpanzees. In reality, our closest relatives are chimpanzees belonging to the Pan genus. This includes pygmy and bonobos. The last common ancestor between humans and chimpanzees was between 8 and 6 million years old.
Humans have evolved a wide range of traits throughout time including bipedalism, the use of fire, and the development of advanced tools. It is only in the past 100,000 years or so that most of the important traits that distinguish us from other species have emerged. They include a huge, complex brain and the capacity of humans to build and use tools, and cultural variety.
Evolution occurs when genetic changes allow members of an organization to better adapt to the environment. Natural selection is the mechanism that drives this change. Certain characteristics are more desirable than others. The ones with the best adaptations are more likely to pass on their genes to the next generation. This is how all species evolve and is the basis of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species which have a common ancestor, tend to develop similar characteristics over time. This 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 control their growth. The structure of DNA is made of base pairs that are arranged in a spiral around sugar and phosphate molecules. The sequence of bases within each strand determines the phenotype, or the individual's characteristic appearance and behavior. Different mutations and reshuffling of the genetic material (known as alleles) during reproduction causes variation in a population.
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia, and Europe. Despite some differences, these fossils all support the notion that modern humans first came into existence in Africa. The genetic and fossil evidence suggests that the first humans left Africa and moved to Asia and Europe.