The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find resources to aid in understanding and teaching evolution. The materials are organized into optional learning paths like "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains that over time, animals that are more adaptable to changing environments do better than those that do not become extinct. Science is concerned with this process of evolution.
What is Evolution?
The term "evolution" has a variety of nonscientific meanings, such as "progress" or "descent with modification." Scientifically it refers to a process of change in the characteristics of organisms (or species) over time. The reason for this change is biological terms on natural selection and drift.
Evolution is an important tenet in modern biology. It is an established theory that has withstood the test of time and a multitude of scientific experiments. Evolution doesn't deal with the existence of God or religious beliefs in the same way as other theories of science, such as the Copernican or germ theory of diseases.
Early evolutionists such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to change in a stepped-like 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.
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 share an ancestry that can be determined through fossils and other lines of evidence. This is the modern view of evolution, and is supported by a variety of lines of scientific research that include molecular genetics.
Scientists don't know how organisms evolved but they are sure that natural selection and genetic drift are responsible for the development of life. People with desirable traits are more likely to survive and reproduce, and these individuals pass their genes on to the next generation. As time passes the gene pool slowly changes and evolves into new species.
Certain scientists use the term"evolution" in reference to large-scale changes, such the formation of a species from an ancestral one. Others, like population geneticists, define the term "evolution" more broadly by referring to a net change in allele frequencies over generations. Both definitions are correct and acceptable, but some scientists believe that allele-frequency definitions omit important features of evolution.
Origins of Life
The emergence of life is an essential stage in evolution. The emergence of life occurs when living systems start to develop at a micro scale, for instance within individual cells.
The origins of life is an issue in a variety of disciplines, including biology, chemistry and geology. The question of how living organisms began is a major topic in science since it poses an enormous challenge to the theory of evolution. It is often described as "the mystery of life" or "abiogenesis."
Traditionally, the idea that life could emerge from nonliving things is called spontaneous generation, or "spontaneous evolution." This was a common belief before Louis Pasteur's experiments proved that it was impossible for the creation of life to occur by the natural process.
Many scientists still think it is possible to go from nonliving substances to living ones. However, the conditions that are required are extremely difficult to reproduce in the laboratory. Researchers interested in the evolution and origins of life are also eager to learn about the physical characteristics of the early Earth as well as other planets.
The development of life is also dependent on a series of complex chemical reactions, which cannot be predicted by basic physical laws. These include the transformation of long information-rich molecules (DNA or RNA) into proteins that perform some function as well as the replication of these complex 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, protein-based cell machinery, is necessary for the onset life. But without life, the chemistry required to enable it does appear to work.
Research in the field of abiogenesis requires collaboration among scientists from a variety of fields. This includes prebiotic scientists, astrobiologists and planet scientists.
Evolutionary Changes
The term "evolution" is used to describe the gradual changes in genetic traits over time. These changes may 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.
This latter mechanism increases the number of genes that confer a survival advantage in an animal, resulting in an overall change in the appearance of the group. The specific mechanisms that cause these changes in evolutionary process include mutation and reshuffling of genes in sexual reproduction, and also gene flow between populations.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo mutations and reshuffles of genes. This happens because, as noted above those who have the beneficial trait tend to have a higher fertility rate than those who do not have it. Over the course of many generations, this variation in the numbers of offspring born could result in gradual changes in the average number of advantageous characteristics in a particular population.
One good example is the growth of the size of the beaks on different species of finches found on the Galapagos Islands, which have developed beaks with different shapes that allow them to easily access food in their new environment. These changes in form and shape can also help create new organisms.
The majority of the changes that occur are caused by one mutation, but occasionally, multiple mutations occur simultaneously. The majority of these changes are neither harmful nor even harmful to the organism, but a small percentage can have a positive impact on 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 could be a time-consuming process that produces the cumulative changes that ultimately lead to the creation of a new species.
Many people confuse the concept of evolution with the idea that the traits inherited from parents can be altered through conscious choice, or through use and abuse, a concept called soft inheritance. This is a misinterpretation of the biological processes that lead to the process of evolution. A more precise description is that evolution is a two-step procedure involving the independent and often antagonistic forces of mutation and natural selection.
Origins of Humans
Humans today (Homo sapiens) evolved from primates, a group of mammals that includes chimpanzees and gorillas and bonobos. The earliest human fossils prove that our ancestors were bipeds. They were walkers with two legs. Biological and genetic similarities indicate that we have the same ancestry with Chimpanzees. In reality our closest relatives are chimpanzees from the Pan genus. This includes pygmy and bonobos. The last common human ancestor and chimpanzees was between 8 and 6 million years ago.
As time has passed, humans have developed a range of traits, including bipedalism and the use of 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. These include language, a large brain, the capacity to construct and use complex tools, as well as cultural diversity.
Evolution occurs when genetic changes allow members of an organization to better adapt to their environment. This adaptation is triggered by natural selection, which is a process by which certain traits are preferred over others. The better adjusted are more likely to pass their genes on to the next generation. This is how all species evolve and forms the basis of the theory of evolution.
Scientists refer to it as the "law of Natural Selection." The law says that species that have a common ancestor, tend to develop similar traits over time. This is because these traits make it easier to live and reproduce in their environment.
Every living thing has an molecule called DNA that holds the information needed to guide their growth. The DNA molecule is made up of base pairs that are spirally arranged around sugar molecules and phosphate molecules. The sequence of bases within each strand determines the phenotype, the characteristic appearance and behavior of a person. 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 에볼루션 코리아 Homo neanderthalensis have been discovered in Africa, Asia, and Europe. These fossils, despite a few variations in their appearance, all support the theory of the origins of modern humans in Africa. The fossil and genetic evidence suggests that the first humans left Africa and moved to Asia and Europe.