The Berkeley Evolution Site
Students and teachers who explore 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 explains how animals who are better equipped to adapt to changes in their environments survive longer and those that do not become extinct. Science is all about the process of biological evolutionary change.
What is Evolution?
The term "evolution" can have many nonscientific meanings, including "progress" or "descent with modification." Scientifically it is a term used to describe a changes in the traits of organisms (or species) over time. In terms of biology this change is caused by natural selection and genetic drift.
Evolution is a central tenet of modern biology. It is an accepted theory that has stood up to the test of time and thousands of scientific experiments. Contrary to other theories of science such as the Copernican theory or the germ theory of disease, the evolution theory is not a discussion of religion or God's existence.
Early evolutionists, such as Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical characteristics were predetermined to change, in a gradual manner, as time passes. This was referred to as the "Ladder of Nature" or scala Naturae. Charles Lyell first used this term in 1833 in his Principles of Geology.
Darwin published his theory of evolution in his book On the Origin of Species, written in the early 1800s. It claims that different species of organisms share the same ancestry, which can be traced through fossils and other lines of evidence. This is the current perspective on evolution, and is supported in a wide range of areas of science which include molecular biology.
While scientists don't know the exact mechanism by which organisms evolved, they are confident that the evolution of life on earth is a result of natural selection and genetic drift. Individuals with advantageous characteristics are more likely to live and reproduce. They transmit their genes on to the next generation. Over time, this results in an accumulation of changes to the gene pool which gradually result in new species and forms.
Certain scientists use the term"evolution" in reference to large-scale changes, such the development of one species from an ancestral one. Certain scientists, including population geneticists, define evolution in a broad sense, using the term "net change" to refer to the change in the frequency of alleles across generations. Both definitions are correct and palatable, but certain scientists argue that allele frequency definitions do not include important aspects of evolution.
Origins of Life
One of the most crucial steps in evolution is the appearance of life. The beginning of life takes place when living systems start to evolve at a micro level, such as within individual cells.
The origin of life is an important issue in many areas, including biology and chemical. The origin of life is a topic of great interest in science because it is a challenge to the theory of evolution. It is often called "the mystery of life," or "abiogenesis."
Traditionally, the idea that life can emerge from nonliving things is known as spontaneous generation or "spontaneous evolution." This was a common belief before Louis Pasteur's experiments proved that it was impossible for the development of life to be a result of an entirely natural process.
Many scientists still believe it is possible to make the transition from nonliving materials to living. However, the conditions required are extremely difficult to replicate in labs. This is why scientists studying the origins of life are also keen to understand the physical properties of the early Earth and other planets.
Furthermore, the growth of life is dependent on a sequence of very complex chemical reactions that can't be predicted based on basic physical laws alone. These include the reading and replication of complex molecules, like DNA or RNA, to create proteins that perform a specific function. These chemical reactions can be compared to the chicken-and-egg issue which is the development and emergence of DNA/RNA, a protein-based cell machinery, is required for the onset life. However, without 에볼루션 바카라 무료 , the chemistry that is required to make it possible is working.
Research in the area of abiogenesis requires cooperation among scientists from various disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
The word evolution is usually used today to describe the cumulative changes in the genetic traits of a population over time. These changes could result from adaptation to environmental pressures, as discussed in the entry on Darwinism (see the entry on Charles Darwin for background) or may result from natural selection.
This is a process that increases the frequency of those genes in a species which confer a survival advantage over others, resulting in gradual changes in the appearance of a group. These changes in evolutionary patterns are caused by mutations, reshuffling of genes in the process of sexual reproduction, and also by the flow of genes.
While reshuffling and mutations of genes occur in all organisms and the process by which beneficial mutations are more frequent is called natural selection. This happens because, as mentioned above, those individuals with the advantageous trait are likely to have a higher reproduction rate than those without it. This difference in the number of offspring produced over a number of generations could result in a gradual change in the average number of beneficial traits in the group.
An excellent example is the growing beak size on different species of finches in the Galapagos Islands, which have evolved different shaped beaks to enable them to more easily access food in their new habitat. These changes in the form and shape of organisms could also be a catalyst for the creation of new species.
The majority of changes are caused by one mutation, however sometimes multiple occur simultaneously. Most of these changes may be neutral or even harmful however, a few could have a positive impact on the survival of the species and reproduce and increase their frequency as time passes. This is the process of natural selection, and it could, over time, produce the cumulative changes that eventually result in an entirely new species.
Some people confuse evolution with the idea of soft inheritance, which is the idea that traits inherited from parents can be changed by conscious choice or by abuse. This is a misunderstanding of the nature of evolution, and of the actual biological processes that lead to it. A more precise description is that evolution is a two-step process involving the independent, and often competing, forces of natural selection and mutation.
Origins of Humans
Humans today (Homo sapiens) evolved from primates - a species of mammals that includes chimpanzees and gorillas and bonobos. Our ancestral ancestors were walking on two legs, as evidenced by the oldest fossils. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In fact we are the most closely related to the chimpanzees within the Pan Genus that includes pygmy and pygmy chimpanzees and bonobos. The last common human ancestor and chimpanzees was between 8 and 6 million years ago.
In the course of time, humans have developed a variety of characteristics, including bipedalism and the use of fire. They also invented advanced tools. However, it is only in the last 100,000 years or so that most of the characteristics that differentiate us from other species have emerged. They include language, a large brain, the ability to build and use sophisticated tools, and a cultural diversity.
The process of evolution occurs when genetic changes allow individuals in a group to better adapt to their surroundings. Natural selection is the process that triggers this adaptation. Certain characteristics are more desirable than others. The ones who are better adapted are more likely to pass on their genes to the next generation. This is how all species evolve and the basis of the theory of evolution.
Scientists call this the "law of natural selection." The law states that species which share a common ancestor tend to develop similar characteristics over time. It is because these traits help them to live and reproduce in their environment.
Every living thing has the DNA molecule, which contains the information needed to guide their growth. The structure of DNA is composed of base pair that are arranged in a spiral around phosphate and sugar molecules. The sequence of bases within each strand determines the phenotype, the distinctive appearance and behavior of a person. Variations in a population are caused by mutations and reshufflings in genetic material (known collectively as alleles).
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. Although there are some differences the fossils all support the idea that modern humans first appeared in Africa. The fossil and genetic evidence suggests that the first humans left Africa and migrated to Asia and Europe.