The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find a wealth of resources to aid in understanding and teaching evolution. The resources are organized into optional learning paths such as "What did T. rex taste like?"
Charles Darwin's theory on natural selection describes how species who are better able to adapt to changes in their environments survive longer and those that do not disappear. Science is about this process of evolutionary change.
What is Evolution?
The term "evolution" has a variety of nonscientific meanings. For instance "progress" or "descent with modification." Scientifically, it is a term used to describe a changes in the traits of living things (or species) over time. This change is based in biological terms on natural selection and drift.
Evolution is a fundamental concept in modern biology. It is an established theory that has withstood the test of time and a multitude of scientific studies. Evolution does not deal with spiritual beliefs or God's presence, unlike many 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 traits were predetermined to evolve in a step-like fashion over time. This was called 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 have a common ancestry, which can be traced through fossils and other evidence. This is the current view of evolution, which is supported by a variety of lines of scientific research which includes molecular genetics.
While scientists don't know exactly how organisms developed, they are confident that the evolution of life on earth is the result of natural selection and genetic drift. People with desirable traits are more likely than others to live and reproduce. They transmit their genes on to the next generation. Over time the gene pool gradually changes and evolves into new species.
Some scientists use the term"evolution" to refer to large-scale changes, such the evolution of an animal from an ancestral one. Certain scientists, including population geneticists, define evolution in a broad sense, referring to the net change in allele frequency over generations. Both definitions are valid and reliable, although some scientists argue that the definition of allele frequency is lacking important features of the evolutionary process.
Origins of Life
The birth of life is a crucial step in evolution. This occurs when living systems begin to evolve at the micro level - within cells, for instance.
에볼루션 바카라사이트 of life is an important issue in many disciplines such as biology and the field of chemistry. The origin of life is a subject that is of immense interest to scientists because it challenges the theory of evolution. It is often described as "the mystery of life" or "abiogenesis."
The idea that life could be born from non-living things was called "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 by a natural process.
Many scientists still think it is possible to move from nonliving substances to living ones. However, the conditions required are extremely difficult to reproduce in a laboratory. Researchers interested in the origins and development of life are also eager to understand the physical properties of the early Earth as well as other planets.
The growth of life is dependent on a number of complex chemical reactions which are not predicted by basic physical laws. These include the reading and replication of complex molecules, like DNA or RNA, in order to make proteins that serve a specific function. These chemical reactions can be compared with the chicken-and-egg issue that is the emergence and growth of DNA/RNA, protein-based cell machinery, is necessary for the beginning of life. But, without life, the chemistry required to make it possible is working.
Abiogenesis research requires collaboration with scientists from various fields. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
The term "evolution" is typically used to describe the accumulated changes in the genetic traits of a population over time. These changes may 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 method that increases the frequency of those genes which confer an advantage in survival over others and causes gradual changes in the appearance of a population. The specific mechanisms behind these evolutionary changes are mutation or reshuffling genes during sexual reproduction, and gene flow between populations.
Natural selection is the process that makes beneficial mutations more frequent. All organisms undergo changes and reshuffles in their genes. As previously mentioned, those who possess the desirable characteristic have a higher reproduction rate than those that do not. Over the course of several generations, this variation in the number of offspring produced can result in gradual changes in the average amount of desirable traits in a population.
This is evident in the evolution of various beak shapes for finches from the Galapagos Islands. They have created these beaks to ensure that they can access food more easily in their new environment. These changes in shape and form can also help create new organisms.
The majority of changes are caused by one mutation, although sometimes multiple occur at once. Most of these changes are neutral or even detrimental to the organism, however a small portion of them could have an advantageous impact on survival and reproduction, thus increasing their frequency in the population over time. Natural selection is a process that causes the accumulating change over time that eventually leads to a new species.
Some people confuse the notion of evolution with the idea 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 misunderstood understanding of the nature of evolution, and of the actual biological processes that lead to it. A more accurate description is that evolution involves a two-step process, which involves the separate and often antagonistic forces of natural selection and mutation.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, a group of mammal species that includes gorillas and chimpanzees. The earliest human fossils show that our ancestors were bipeds. They were walkers with two legs. Genetic and biological similarities show that we share a close relationship with chimpanzees. In reality, our closest relatives are the chimpanzees belonging to the Pan genus. This includes pygmy and bonobos. The last common human ancestor 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 advanced tools. It's only within the last 100,000 years that we have developed the majority of our key characteristics. These include a big brain that is complex, the ability of humans to construct and use tools, as well as cultural diversity.
Evolution happens when genetic changes allow individuals in a group to better adapt to their environment. Natural selection is the process that drives this change. Certain traits are preferred over others. The better adaptable are more likely to pass on their genes to the next generation. This is how 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 an ancestor in common will tend to develop similar traits as time passes. This is because these traits allow them to live and reproduce in their environment.
Every living thing has DNA molecules, which contains the information needed to direct their growth and development. The DNA molecule is composed of base pairs that are arranged in a spiral around sugar molecules and phosphate molecules. The sequence of bases within each strand determines the phenotype, or the individual's characteristic appearance and behavior. A variety of changes and reshuffling of genetic material (known as alleles) during reproduction causes variations in a population.
Fossils from the first human species, Homo erectus, as well as Homo neanderthalensis have been discovered in Africa, Asia and Europe. These fossils, despite variations in their appearance, all support the theory of the origins of modern humans in Africa. The genetic and fossil evidence suggests that the first humans left Africa and moved to Asia and Europe.