The Berkeley Evolution Site
The Berkeley site contains resources that can help students and teachers learn about and teach evolution. The materials are organized into optional learning paths, such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains how over time creatures that are better able to adapt biologically to changing environments thrive, and those that are not extinct. Science is concerned with the process of biological evolutionary change.
What is Evolution?
The term "evolution" can be used to refer to a variety of nonscientific meanings. For instance it could mean "progress" and "descent with modifications." Scientifically it refers to a changes in the traits of living organisms (or species) over time. In terms of biology, this change is caused by natural selection and genetic drift.
Evolution is the central tenet of modern biology. It is a theory that has been tested and confirmed by thousands of scientific tests. In contrast to other theories in science such as the Copernican theory or the germ theory of disease, the evolution theory does not address questions of spiritual belief or God's existence.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical characteristics were predetermined to change in a step-like manner, as time passes. This was referred to as the "Ladder of Nature" or scala naturae. Charles Lyell used the term to describe this concept 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 asserts that all species of organisms share an ancestry that can be traced through fossils and other evidence. This is the modern view of evolution, which is supported by many lines of scientific research, including molecular genetics.
Scientists do not know 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 survive and reproduce, and these individuals pass their genes on to the next generation. Over time, the gene pool gradually changes and evolves into new species.
Certain scientists use the term evolution in reference to large-scale changes, like the evolution of one species from an ancestral one. Certain scientists, including population geneticists, define evolution in a more broad sense by referring to the net change in the frequency of alleles across generations. Both definitions are correct and palatable, but certain scientists argue that allele frequency definitions omit important features of evolution.
Origins of Life
The emergence of life is a key stage in evolution. The emergence of life happens when living systems begin to develop at a microscopic scale, for instance within individual cells.
The origins of life are one of the major topics in various disciplines, including biology, chemistry and geology. The origin of life is an area that is of immense interest to scientists because it is a challenge to the theory of evolution. It is often referred to as "the mystery of life" or "abiogenesis."
Traditionally, the idea that life could emerge from nonliving things is known as spontaneous generation, or "spontaneous evolution." This was a popular belief prior to Louis Pasteur's experiments proved that it was impossible for the emergence of life to occur by an entirely natural process.
Many scientists believe it is possible to go from nonliving to living substances. However, the conditions needed are extremely difficult to replicate in labs. Researchers who are interested in the evolution and origins of life are also keen to know the physical properties of the early Earth as well as other planets.
The development of life is dependent on a variety of complex chemical reactions, which are not predicted by the basic physical laws. This includes the conversion of long, information-rich molecules (DNA or RNA) into proteins that carry out functions as well as the replication of these complex molecules to produce new DNA or sequences of RNA. These chemical reactions can be compared to the chicken-and-egg issue which is the development and emergence of DNA/RNA, protein-based cell machinery, is necessary for the onset life. However without life, the chemistry needed to make it possible appears to be working.
Abiogenesis research requires collaboration between researchers from different disciplines. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
The term "evolution" is typically used to describe the cumulative changes in genetic characteristics of an entire population over time. These changes may result from adaptation to environmental pressures as explained in the article on Darwinism (see the entry on Charles Darwin for background) or may result from natural selection.
This latter mechanism increases the number of genes that confer an advantage for survival in an animal, resulting in an overall change in the appearance of the group. These changes in evolutionary patterns are caused by mutations, reshuffling genes in the process of sexual reproduction, and also by gene flow.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo changes and reshuffles of their genes. This is because, as we've mentioned earlier, those individuals with the beneficial trait tend to have a higher reproductive rate than those without it. This variation in the number of offspring produced over a number of generations could result in a gradual change in the average number advantageous characteristics in the group.
This can be seen in the evolution of various beak shapes for finches from the Galapagos Islands. They have developed these beaks so they can get food more easily in their new environment. These changes in form and shape can also help create new organisms.
The majority of changes are caused by one mutation, but sometimes several occur simultaneously. Most of these changes may be negative or even harmful, but a small number may have a positive effect on the survival of the species and reproduce and increase their frequency over time. This is the process of natural selection, and it could eventually result in the accumulating changes that ultimately lead to a new species.
Many people mistakenly associate evolution with the concept of soft inheritance, which is the idea that inherited traits 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. A more accurate description of evolution is that it is a two-step process which involves the separate and often antagonistic forces of natural selection and mutation.
Origins of Humans
Modern humans (Homo sapiens) evolved from primates - a species of mammals that also includes gorillas, chimpanzees, and bonobos. Our ancestral ancestors were walking on two legs, as evidenced by the first fossils. Genetic and biological similarities suggest that we are closely related to Chimpanzees. In reality, our closest relatives are the chimpanzees from the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor of modern humans and chimpanzees was between 8 and 6 million years ago.
As time has passed, humans have developed a number of traits, including bipedalism and the use fire. They also created 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. These include a big brain that is complex and the capacity of humans to construct and use tools, as well as the diversity of our culture.
에볼루션사이트 occurs when genetic changes enable members of a group to better adapt to their environment. This adaptation is triggered by natural selection, a process that determines certain traits are more desirable than other traits. The better adapted are more likely to pass their genes on to the next generation. This is the way that all species evolve and forms the foundation of the theory of evolution.
Scientists call this the "law of natural selection." The law states that species which have a common ancestor are more likely to develop similar characteristics over time. This is because those traits make it easier for them to survive and reproduce in their environments.
Every living thing has a DNA molecule that contains the information needed to control their growth. The structure of DNA is composed of base pairs which are arranged in a spiral, around phosphate and sugar molecules. The sequence of bases found in each strand determines the phenotype, the appearance and behavior of an individual. Variations in a population can be caused by mutations and reshufflings in genetic material (known collectively as alleles).
Fossils of the earliest human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. Although there are some differences, these 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.