The Berkeley Evolution Site
The Berkeley site offers resources that can help students and teachers learn about and teach evolution. The materials are organized into optional learning paths like "What did T. rex taste like?"
Charles Darwin's theory on natural selection explains how creatures who are better able to adapt biologically to a changing environment survive over time and those who do not disappear. Science is about the process of biological evolution.
What is Evolution?
The term "evolution" can be used to refer to a variety of nonscientific meanings. For instance it could mean "progress" and "descent with modifications." It is scientifically based and is used to describe the process of changing characteristics over time in organisms or species. In terms of biology this change is due to natural selection and genetic drift.
Evolution is an important concept in modern biology. It is an accepted theory that has withstood the test of time and a multitude of scientific experiments. It does not address God's presence or spiritual beliefs in the same way as other scientific theories such as the Copernican or germ theory of disease.
Early evolutionists, such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to evolve in a gradual manner over time. They called this 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 published in the early 1800s. It asserts that different species of organisms share a common ancestry, which can be traced through fossils and other lines of evidence. This is the current understanding of evolution, which is supported by numerous lines of research in science that include molecular genetics.
Scientists aren't sure the evolution of organisms, but they are confident that natural selection and genetic drift is the primary reason for the evolution of life. Individuals with advantageous characteristics are more likely than others to survive and reproduce. These individuals transmit their genes on to the next generation. Over time, the gene pool gradually changes and evolves into new species.
Some scientists also use the term evolution to describe large-scale evolutionary changes, such as the formation of the new species from an ancestral species. Other scientists, like population geneticists, define it more broadly, referring to the net variation in the frequency of alleles over generations. Both definitions are valid and reliable, although some scientists argue that the allele-frequency definition is missing crucial aspects of the evolutionary process.
Origins of Life
The development of life is an essential step in the process of evolution. The beginning of life takes place when living systems begin to develop at a micro level, such as within individual cells.
The origin of life is an issue in a variety of disciplines such as biology, chemistry, and geology. The nature of life is a subject of interest in science because it challenges the theory of evolution. It is often described as "the mystery of life" or "abiogenesis."
The notion that life could emerge 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 development of living organisms was not possible through a natural process.
Many scientists still believe it is possible to go from nonliving materials to living. However, the conditions needed are extremely difficult to replicate in labs. Researchers interested in the origins and evolution of life are also eager to learn about the physical characteristics of the early Earth as well as other planets.
Furthermore, the growth of life is a sequence of very complex chemical reactions that can't be predicted from the fundamental physical laws alone. These include the reading and re-reading of complex molecules, such as DNA or RNA, to create proteins that perform a particular function. These chemical reactions are often compared to the chicken-and-egg dilemma of how life first appeared in the first place. The appearance of DNA/RNA and protein-based cell machinery is essential to the birth of life, however, without the development of life, the chemical reaction that is the basis for it does not appear to work.
Research in the area of abiogenesis requires collaboration between scientists from many different fields. This includes prebiotic chemists, astrobiologists, planetary scientists, geologists and geophysicists.
Evolutionary Changes
The term "evolution" today is used to describe general changes in genetic traits over time. These changes could result from the response 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 genes in a species which confer an advantage in survival over others, resulting in a gradual change in the appearance of a group. The specific mechanisms responsible for these evolutionary changes are mutation, reshuffling of genes during sexual reproduction, and gene flow between populations.
While reshuffling and mutation of genes occur in all organisms and the process by which beneficial mutations are more frequent is referred to as natural selection. As noted above, individuals with the beneficial characteristic have a higher reproduction rate than those that do not. This variation in the number of offspring produced over a number of generations could result in a gradual shift in the average number of beneficial traits in the group.
This is evident in the evolution of different beak designs on finches that are found in the Galapagos Islands. They have developed these beaks in order that they can eat more easily in their new habitat. These changes in shape and form could also aid in the creation of new species.
The majority of changes are caused by a single mutation, although sometimes multiple occur at the same time. The majority of these changes are neutral or even harmful to the organism however, a small proportion of them can have an advantageous impact on survival and reproduction, thus increasing their frequency in the population over time. Natural selection is a process that can produce the accumulating change over time that leads to the creation of a new species.
Some people confuse the notion of evolution with the notion that the traits inherited from parents can be altered by conscious choice or by use and abuse, a notion called soft inheritance. This is a misunderstanding of the biological processes that lead to evolution. It is more precise to say that evolution is a two-step independent process, that is influenced by the forces of natural selection as well as mutation.
Origins of Humans
Humans of today (Homo sapiens) evolved from primates, a group of mammals that also includes chimpanzees and gorillas and bonobos. The earliest human fossils prove that our ancestors were bipeds, walking on two legs. Genetic and biological similarities show that we share the same ancestry with the chimpanzees. In actual fact we are the most closely connected to chimpanzees belonging to the Pan Genus, which includes pygmy chimpanzees and bonobos. The last common ancestor shared between modern humans and chimpanzees dated 8 to 6 million years old.
Humans have evolved a wide range of traits over time including bipedalism, the use of fire, and the development of advanced tools. It is only within the last 100,000 years that we have developed the majority of our important traits. These include language, large brain, the ability to construct and use complex tools, as well as the ability to adapt to cultural differences.
Evolution occurs when genetic changes enable members of a group to better adapt to their environment. This adaptation is driven by natural selection, which is a process by which certain traits are preferred over others. The ones who are better adaptable are more likely to pass their genes on to the next generation. This is the way that all species evolve and forms the foundation of the theory of evolution.
에볼루션 바카라 무료체험 call this the "law of natural selection." The law says that species that have a common ancestor, tend to develop similar characteristics over time. It is because these traits make it easier to reproduce and survive within their environment.
All organisms possess a DNA molecule that contains the information necessary to direct their growth. The structure of DNA is made of base pairs that 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. Variations in a population are caused by mutations and reshufflings of genetic material (known collectively as alleles).
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 hypothesis that modern humans first came into existence in Africa. Genetic and fossil evidence also suggest that early humans came from Africa into Asia and then Europe.