The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find resources to help them understand and teach evolution. The materials are organized into a variety of learning paths such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection describes how species that are better equipped to adapt biologically to a changing environments survive longer and those who do not disappear. This process of biological evolution is what science is all about.
What is Evolution?
The word evolution has many nonscientific meanings, such as "progress" or "descent with modification." Scientifically, it is a term used to describe a changing the characteristics of living organisms (or species) over time. The reason for this change is biological terms on natural selection and drift.
Evolution is a fundamental tenet in modern biology. It is a well-supported theory that has stood the test of time and thousands of scientific studies. In contrast to other theories in science, such as the Copernican theory or the germ theory of disease, evolution is not a discussion of religion or the existence of God.
Early evolutionists, like 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 known as the "Ladder of Nature" or scala Naturae. Charles Lyell used the term to describe this idea in his Principles of Geology, first published in 1833.
In the early 1800s, Darwin formulated his theory of evolution and published it in his book On the Origin of Species. It states that all species of organisms have common ancestors that can be traced by fossils and other evidence. This is the current view of evolution that is supported by a variety of lines of research in science, including molecular genetics.
Scientists aren't sure how organisms evolved, but they are confident that natural selection and genetic drift are responsible for the evolution of life. People with traits that are advantageous are more likely to live and reproduce, and these individuals transmit their genes to the next generation. As time passes the gene pool slowly changes and evolves into new species.
Some scientists also use the term"evolution" to refer to large-scale changes in evolutionary processes, such as the formation of a new species from an ancestral species. Certain scientists, including population geneticists, define the term "evolution" in a broad sense, referring to the net change in the frequency of alleles across generations. Both definitions are valid and reliable however some scientists believe that the allele-frequency definition omits important features of the evolutionary process.
Origins of Life
The development of life is a crucial stage in evolution. The emergence of life happens when living systems begin to evolve at a micro scale, for instance within individual cells.
The origin of life is one of the major topics in various disciplines such as biology, chemistry and geology. The origin of life is a subject of great interest in science, as it is a challenge to the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
The notion that life could arise from non-living objects was referred to as "spontaneous generation" or "spontaneous evolutionary". It was a popular belief prior to Louis Pasteur's tests proved that the development of living organisms was not possible through a 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 replicate in labs. Researchers studying the nature of life are also keen to understand the physical properties of the early Earth and other planets.
The development of life is dependent on a variety of complex chemical reactions, that are not predicted by the basic physical laws. These include the reading and replication of complex molecules, such as DNA or RNA, to create proteins that perform a particular function. These chemical reactions can be compared to a chicken-and egg problem which is the development and emergence of DNA/RNA, the protein-based cell machinery, is necessary for the onset life. Although, without life, the chemistry that is required to make it possible is working.
Abiogenesis research requires collaboration among scientists from various fields. This includes prebiotic chemists the astrobiologists, the planet scientists, geologists and geophysicists.
Evolutionary Changes
The term "evolution" is typically used today to describe the accumulated changes in the genetic traits of populations over time. These changes could be the result of adaptation to environmental pressures as explained in Darwinism.
This process increases the number of genes that confer a survival advantage in a species, resulting in an overall change in the appearance of an entire group. These evolutionary changes are caused by mutations, reshuffling of genes during sexual reproduction and the flow of genes.
Natural selection is the process that makes beneficial mutations more common. All organisms undergo changes and reshuffles in their genes. 에볼루션 바카라 체험 is because, as mentioned above, those individuals with the advantageous trait are likely to have a higher reproduction rate than those with it. This difference in the number of offspring produced over many generations can result in a gradual shift in the average number advantageous traits in the group.
An excellent example is the increase in beak size on different species of finches on the Galapagos Islands, which have developed different beak shapes to allow them to more easily access food in their new environment. These changes in shape and form could also aid in the creation of new species.
Most of the changes that occur are the result of a single mutation, but occasionally several will happen simultaneously. The majority of these changes are neither harmful nor even detrimental to the organism, however a small portion of them could have an advantageous impact on the survival of the organism and its reproduction, thereby increasing their frequency in the population 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 mistakenly associate evolution with the concept of soft inheritance which is the notion that traits inherited from parents can be changed through conscious choice or by abuse. This is a misinterpretation of the nature of evolution, and of the actual biological processes that lead to it. It is more accurate to say that the process of evolution is a two-step independent process, that is influenced by the forces of natural selection and mutation.
Origins of Humans
Humans of today (Homo sapiens) evolved from primates - a species of mammals that also includes chimpanzees and gorillas and bonobos. Our ancestors walked on two legs, as shown by the earliest fossils. Genetic and biological similarities suggest that we have an intimate relationship with chimpanzees. In fact, our closest relatives are the chimpanzees from the Pan genus. This includes pygmy as well as bonobos. The last common ancestor shared between humans and chimpanzees was between 8 and 6 million years old.
As time has passed humans have developed a range of characteristics, such as bipedalism and the use of fire. They also created advanced tools. It's only in the last 100,000 years that we've developed the majority of our essential characteristics. They include language, a large brain, the ability to create and utilize complex tools, and cultural diversity.
The process of evolution occurs when genetic changes allow members of a population to better adapt to their environment. Natural selection is the process that drives this adaptation. Certain traits are preferred over others. The ones with the best adaptations are more likely to pass on their genes to the next generation. This is the way all species evolve and the foundation for the theory of evolution.
Scientists call this the "law of natural selection." The law states that species that have a common ancestor are more likely to develop similar characteristics over time. This is because these characteristics make it easier for them to live and reproduce in their environment.
All organisms have DNA molecules, which provides the information necessary to guide their growth and development. The DNA molecule is made up of base pairs that are spirally arranged around phosphate molecules 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 can be 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. These fossils, despite a few differences in their appearance, all support the theory of the origins of modern humans in Africa. The evidence from fossils and genetics suggests that early humans left Africa and migrated to Asia and Europe.