The Berkeley Evolution Site
Teachers and students who browse the Berkeley site will find resources to aid in understanding and teaching evolution. The resources are arranged into different learning paths, such as "What did T. rex taste like?"
Charles Darwin's theory on natural selection explains how animals who are better able to adapt to changes in their environments over time, and those who do not end up becoming extinct. Science is all about the process of biological evolutionary change.
What is Evolution?
The term "evolution" can have many nonscientific meanings. For example it could refer to "progress" and "descent with modifications." Scientifically it refers to a process of changing the characteristics of living things (or species) over time. In biological terms this change is caused by natural selection and genetic drift.
Evolution is one of the fundamental tenets of modern biology. It is a theory that has been proven by a myriad of scientific tests. It does not address spiritual beliefs or God's presence in the same way as other theories in science, like the Copernican or germ theory of diseases.
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. This was referred to as the "Ladder of Nature" or scala naturae. Charles Lyell used the term to describe this idea in his Principles of Geology, first published in 1833.
Darwin revealed his theory of evolution in his book On the Origin of Species published in the early 1800s. It asserts that all species of organisms share an ancestry that can be traced by fossils and other evidence. This is the current understanding of evolution, and is supported by a variety of research lines in science that include molecular genetics.
Scientists don't know how organisms evolved but they are sure that natural selection and genetic drift are the primary reason for the evolution of life. Individuals with advantageous traits are more likely to live and reproduce, and these individuals transmit their genes to the next generation. Over time this leads to an accumulation of changes in the gene pool that gradually lead to new species and forms.
Certain scientists also use the term evolution to refer to large-scale changes in evolutionary processes such as the creation of the new species from an ancestral species. Others, like population geneticists, define it more broadly by referring to a net change in the frequency of alleles across generations. 에볼루션바카라사이트 are acceptable and precise however some scientists believe that the allele-frequency definition is missing crucial aspects of the evolutionary process.
Origins of Life
The development of life is a crucial step in the process of evolution. The emergence of life happens when living systems begin to develop at a micro scale, for instance within cells.
The origin of life is an important topic in a variety of disciplines that include biology and chemical. The question of how living things started has a special place in science due to it being an important challenge to the theory of evolution. It is sometimes referred to "the mystery" of life or "abiogenesis."
The idea that life could arise from non-living matter was known as "spontaneous generation" or "spontaneous evolutionary". This was a popular belief prior to Louis Pasteur's tests proved that the creation of living organisms was not achievable through the natural process.
Many scientists still think it is possible to transition from nonliving substances to living ones. However, the conditions that are required are extremely difficult to reproduce in a laboratory. Researchers who are interested in the origins and evolution of life are also eager to understand the physical properties of the early Earth as well as other planets.
The development of life is dependent on a number of complex chemical reactions which cannot be predicted by the basic physical laws. This includes the conversion of long, information-rich molecules (DNA or RNA) into proteins that carry out a function as well as the replication of these intricate molecules to produce new DNA or sequences of RNA. These chemical reactions are often compared to the chicken-and-egg issue of how life began: The development of DNA/RNA as well as proteins-based cell machinery is vital to the birth of life, but without the emergence of life, the chemical reaction that is the basis for it is not working.
Research in the field of abiogenesis requires collaboration between scientists from various fields. This includes prebiotic chemists, astrobiologists, planetary scientists, geologists and geophysicists.
Evolutionary Changes
Today, the word evolution is used to describe the gradual changes in genetic traits over time. These changes can result from the response to environmental pressures as explained in the article on Darwinism (see the entry on Charles Darwin for background) or natural selection.
This latter mechanism increases the number of genes that confer a survival advantage in a species, resulting in an overall change in the appearance of an entire group. The specific mechanisms behind these evolutionary changes include mutation or reshuffling genes during sexual reproduction, and gene flow between populations.
While reshuffling and mutations of genes are common in all organisms The process through which beneficial mutations are more frequent is called natural selection. This occurs because, as we've mentioned earlier, those individuals with the advantageous trait are likely to have a higher reproduction rate than those with it. Over many generations, this differential in the numbers of offspring born could result in a gradual shift in the average amount of desirable traits in a population.
This can be seen in the evolution of different beak shapes for finches from the Galapagos Islands. They have developed these beaks so that they can access food more easily in their new habitat. These changes in the form and shape of organisms can also help create new species.
The majority of changes are caused by a single mutation, although sometimes multiple occur at once. The majority of these changes are neutral or even harmful to the organism however a small portion of them could be beneficial to survival and reproduction, thus increasing the frequency of these changes in the population over time. Natural selection is a process that could result in the accumulation of change over time that leads to the creation of a new species.
Some people confuse the idea of evolution with the idea that the traits inherited from parents can be altered by conscious choice or by use and abuse, which is known as soft inheritance. This is a misinterpretation of the nature of evolution and of the actual biological processes that cause it. A more accurate description is that evolution involves a two-step process, which involves the separate, and often competing, forces of natural selection and mutation.
Origins of Humans
Modern humans (Homo sapiens) evolved from primates - a species of mammals that includes chimpanzees and gorillas and bonobos. The earliest human fossils prove that our ancestors were bipeds. They were walking on two legs. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In actual fact our closest relatives are the chimpanzees belonging to the Pan genus. This includes pygmy as well as bonobos. The last common human ancestor as well as chimpanzees was born between 8 and 6 million years ago.
Humans have developed a range of traits over time, including bipedalism, the use of fire and advanced tools. It's only within the last 100,000 years that we've developed the majority of our essential characteristics. These include language, large brain, the capacity to construct and use complex tools, and cultural diversity.
Evolution occurs when genetic changes allow members of a group to better adapt to their environment. Natural selection is the mechanism that drives this adaptation. Certain characteristics are more desirable than others. Those with the better adaptations are more likely to pass on their genes to the next generation. This is the way 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 have a common ancestor, tend to develop similar characteristics over time. It is because these traits allow them to live and reproduce in their environment.
Every organism has a DNA molecule that provides the information necessary to direct their growth and development. The DNA molecule consists of base pairs that are spirally arranged around sugar molecules and phosphate molecules. The sequence of bases within each strand determines phenotype or the individual's unique appearance and behavior. Variations in mutations and reshuffling of the genetic material (known as alleles) during sexual reproduction can cause variations in a population.
Fossils of the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. While there are some differences between them, these fossils all support the hypothesis that modern humans first came into existence in Africa. The genetic and fossil evidence suggests that the first humans left Africa and moved to Asia and Europe.