The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find resources to help them understand and teach evolution. The resources are organized into different learning paths like "What does T. rex look like?"
Charles Darwin's theory of natural selection explains how in time, creatures more able to adapt to changing environments do better than those that don't become extinct. Science is about this process of biological evolution.
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 change in the characteristics of living things (or species) over time. This change is based in biological terms on natural drift and selection.
Evolution is the central tenet of modern biology. It is a concept that has been tested and confirmed through thousands of scientific tests. Contrary to other theories of science such as the Copernican theory or the germ theory of disease, the evolution theory does not address issues of spiritual belief or God's existence.
Early evolutionists like Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to evolve in a gradual manner over time. They referred to this as the "Ladder of Nature" or the scala naturae. Charles Lyell used the term to describe this idea in his Principles of Geology, first published in 1833.
Darwin presented his theory of evolution in his book On the Origin of Species published in the early 1800s. It asserts that all species of organisms have an ancestry that can be traced by fossils and other evidence. This is the modern view of evolution, which is supported by a variety of areas of science, including molecular biology.
Although scientists aren't able to determine exactly how organisms developed however they are sure that the evolution of life on earth is the result of natural selection and genetic drift. People with advantages are more likely to live and reproduce. They transmit their genes on to the next generation. As time passes, this results in a gradual accumulation of changes in the gene pool, which eventually create new species and types.
Some scientists employ the term evolution in reference to large-scale changes, like the development of a species from an ancestral one. Some scientists, like population geneticists, define evolution in a more broad sense by referring to the net variation in the frequency of alleles over generations. Both definitions are acceptable and accurate however, some scientists claim that the allele-frequency definition is missing crucial aspects of the evolutionary process.
Origins of Life
The birth of life is a key step in the process of evolution. The emergence of life occurs when living systems start to develop at a microscopic level, like within cells.
The origins of life is a topic in many disciplines that include biology, chemistry and geology. The nature of life is an area of interest in science, as it challenges the theory of evolution. It is often called "the mystery of life," or "abiogenesis."
The idea that life could be born from non-living objects was referred to as "spontaneous generation" or "spontaneous evolutionary". It was a popular belief before Louis Pasteur's tests showed that the development of living organisms was not possible by a natural process.
Many scientists believe it is possible to move from nonliving substances to living ones. The conditions required to create life are difficult to replicate in a laboratory. Researchers interested in the origins and development 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 dependent on a variety of complex chemical reactions, that are not predicted by simple physical laws. These include the transformation of long, information-rich molecules (DNA or RNA) into proteins that perform functions and the replication of these complex molecules to generate new DNA or RNA sequences. These chemical reactions are often compared to the chicken-and-egg dilemma of how life began in the first place. The emergence of DNA/RNA and proteins-based cell machinery is vital to the birth of life, however, without the development of life the chemical reaction that is the basis for it is not working.
Research in the area of abiogenesis requires collaboration among scientists from many different fields. This includes prebiotic chemists the astrobiologists, the planet scientists geophysicists, geologists, and geophysicists.
Evolutionary Changes
The word evolution is usually used today to refer to the accumulated changes in genetic characteristics of populations over time. 에볼루션바카라 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 method that increases the frequency of those genes in a species that confer a survival advantage over others which results in gradual changes in the overall appearance of a particular population. These evolutionary changes are triggered by mutations, reshuffling genes during sexual reproduction and the flow of genes.
While reshuffling and mutations of genes happen in all living things and the process by which beneficial mutations are more prevalent is called natural selection. This happens because, as noted above those who have the advantageous trait are likely to have a higher fertility rate than those who do not have it. This differential in the number of offspring that are produced over many generations can result in a gradual change in the average number advantageous traits within the group.
A good example of this is the increase in beak size on different species of finches on the Galapagos Islands, which have developed beaks with different shapes to allow them to more easily access food in their new habitat. These changes in shape and form could also aid in the creation of new species.
Most of the changes that occur are caused by one mutation, but occasionally, multiple mutations occur simultaneously. Most of these changes are not harmful or even harmful to the organism however a small portion of them could be beneficial to the survival of the organism and its reproduction, thereby increasing their frequency in the population over time. This is the process of natural selection and it could, over time, produce the accumulating changes that eventually lead to an entirely new species.
Some people mistakenly associate evolution with the concept of soft inheritance, which is the idea that traits inherited from parents can be changed through deliberate choice or misuse. 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 evolution is a two-step independent process, which involves the forces of natural selection as well as mutation.
Origins of Humans
Humans of today (Homo sapiens) evolved from primates - a group of mammals that also includes chimpanzees and gorillas and bonobos. Our ancestors walked on two legs, as shown by the oldest fossils. Genetic and biological similarities suggest that we share a close relationship with chimpanzees. In actual fact our closest relatives are chimpanzees belonging to the Pan genus. This includes pygmy and bonobos. The last common ancestor between modern humans and chimpanzees was 8 to 6 million years old.
In the course of time, humans have developed a range of characteristics, such as bipedalism and the use fire. They also created advanced tools. It is only in the last 100,000 years or so that the majority of the essential characteristics that differentiate us from other species have emerged. These include a big brain that is complex human ability to build and use tools, as well as cultural variety.
The process of evolution occurs when genetic changes enable members of an organization to better adapt to the environment. Natural selection is the process that triggers this adaptation. Certain traits are preferred over others. Those with the better adaptations 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 it as the "law of natural selection." The law states that species that have an ancestor in common will tend to acquire similar traits over time. This is because these traits make it easier to reproduce and survive within their environment.
Every organism has a DNA molecule that contains the information needed to guide their growth. The structure of DNA is made of base pairs that are arranged in a spiral around sugar and phosphate molecules. The sequence of bases in each strand determines the phenotype - the appearance and behavior of a person. A variety of changes and reshuffling of genetic material (known as alleles) during reproduction causes variation in a population.
Fossils from the early human species Homo erectus, and Homo neanderthalensis have been found in Africa, Asia and Europe. Although there are 무료에볼루션 support the hypothesis that modern humans first appeared in Africa. Genetic and fossil evidence also suggest that early humans migrated out of Africa into Asia and then Europe.