The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find resources to assist them in understanding and teaching evolution. The resources are organized into various learning paths that can be used in a variety of ways for example "What does T. rex look like?"
Charles Darwin's theory of natural selection explains that over time creatures that are more adaptable to changing environments thrive, and those that don't become extinct. This process of biological evolution is the main focus of science.
What is Evolution?
The word evolution can have many nonscientific meanings. For instance, it can mean "progress" and "descent with modifications." It is scientifically based and is used to describe the process of change of traits over time in organisms or species. In terms of biology the change is due to natural selection and genetic drift.
Evolution is a key principle in modern biology. It is a concept that has been tested and verified through thousands of scientific tests. Unlike many other scientific theories, such as the Copernican theory or the germ theory of disease, evolution does not address issues of religious belief or the existence of God.
Early evolutionists, such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to change in a gradual manner over time. 에볼루션 was known as 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 states that all species of organisms have an ancestry that can be traced through fossils and other evidence. This is the current understanding of evolution, which is supported by many lines of research in science which includes molecular genetics.
Scientists do not know how organisms evolved however they are certain that natural selection and genetic drift are the reason for the development of life. People with advantages are more likely than others to survive and reproduce. They transmit their genes on to the next generation. In time this leads to a gradual accumulation of changes to the gene pool that gradually create new species and forms.
Some scientists employ the term"evolution" to refer to large-scale changes, like the evolution of an animal from an ancestral one. Other scientists, such as population geneticists, define it more broadly by referring to the net variation in the frequency of alleles over generations. Both definitions are valid and acceptable, however some scientists believe that allele-frequency definitions miss important aspects of the evolution.
Origins of Life
One of the most crucial steps in evolution is the emergence of life. This occurs when living systems begin to develop at a micro-level - within cells, for example.
The origin of life is a topic in many disciplines that include geology, chemistry, biology and chemistry. The origin of life is a subject of interest in science because it is a challenge to the theory of evolution. It is sometimes referred to "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 popular view before Louis Pasteur's research showed that it was impossible for the emergence of life to occur by an entirely natural process.
Many scientists believe it is possible to transition from nonliving substances to living ones. The conditions required to create life are difficult to replicate in a laboratory. Researchers studying the origins of life are also interested in understanding the physical properties of early Earth and other planets.
In addition, the development of life is dependent on the sequence of extremely complex chemical reactions that cannot be predicted from 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 are often compared with the chicken-and-egg problem of how life first appeared in the first place. The development of DNA/RNA as well as proteins-based cell machinery is vital for the onset of life, however, without the emergence of life, the chemistry that makes it possible is not working.
Abiogenesis research requires collaboration with researchers from different disciplines. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
Today, the word evolution is used to describe the general changes in genetic traits over time. These changes can result from adaptation to environmental pressures, as explained in the article on Darwinism (see the entry on Charles Darwin for background) or natural selection.
This is a method that increases the frequency of genes that confer an advantage in survival over other species which results in gradual changes in the overall appearance of a group. These changes in evolutionary patterns are caused by mutations, reshuffling genes in the process of sexual reproduction, and also by gene flow.
While mutation and reshuffling of genes are common in all organisms, the process by which beneficial mutations are more frequent is known as natural selection. As mentioned above, those who possess the desirable characteristic have a higher reproduction rate than those that do not. This variation in the number of offspring born over a number of generations could result in a gradual change in the number of advantageous traits within the group.
An excellent example is the growth of beak size on different species of finches in the Galapagos Islands, which have evolved different shaped beaks that allow them to easily access food in their new home. These changes in the shape and form of organisms could also help create new species.
The majority of changes are caused by one mutation, but sometimes several occur at once. Most of these changes can be negative or even harmful, but a small number can have a beneficial impact on survival and reproduce and increase their frequency over time. This is the process of natural selection, and it is able to, over time, produce the accumulating changes that eventually result in a new species.
Many people confuse the concept of evolution with the notion that traits inherited can be altered through conscious choice, or through use and abuse, a notion known as soft inheritance. 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 involves a two-step process, which involves the separate, and often competing, forces of mutation and natural selection.
Origins of Humans
Modern humans (Homo Sapiens) evolved from primates, a group of mammal species that includes gorillas and chimpanzees. The earliest human fossils prove that our ancestors were bipeds. They were walkers on two legs. Biological and genetic similarities indicate that we have the same ancestry with Chimpanzees. In fact our closest relatives are chimpanzees of the Pan genus. This includes pygmy, as well as bonobos. The last common human ancestor as well as chimpanzees lived between 8 and 6 million years ago.
Humans have evolved a variety of traits throughout time such as bipedalism, use of fire, and the development of advanced tools. But it's only in the last 100,000 years or so that the majority of the essential traits that distinguish us from other species have developed. These include a large brain that is complex human ability to build and use tools, and the diversity of our culture.
The process of evolution occurs when genetic changes enable members of an organization to better adapt to the environment. This adaptation is triggered by natural selection, a process whereby certain traits are preferred over others. The ones who are better adapted are more likely to pass their genes on to the next generation. This is how all species evolve and is the basis for the theory of evolution.
Scientists call this the "law of natural selection." The law states species that have a common ancestor are likely to acquire similar traits as time passes. It is because these traits make it easier to live and reproduce in their environment.
Every living thing has a DNA molecule that provides the information necessary to control 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 found in each strand determines the phenotype - the appearance and behavior of a person. The variations in a population are caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils from the earliest human species Homo erectus, and Homo neanderthalensis have been discovered in Africa, Asia and Europe. Despite some differences the fossils all support the idea that modern humans first came into existence in Africa. Genetic and fossil evidence also suggest that early humans moved out of Africa into Asia and then Europe.