The Berkeley Evolution Site
Teachers and students who browse 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 does T. rex look like?"
Charles Darwin's theory of natural selection explains that in time, creatures more adaptable to changing environments do better than those that are not extinct. Science is about this process of evolutionary change.
What is Evolution?
The term "evolution" can have many nonscientific meanings. For instance "progress" or "descent with modification." It is a scientific term that is used to describe the process of changing characteristics in a species or species. This change is based in biological terms on natural drift and selection.
Evolution is a fundamental tenet in the field of biology today. It is a theory that has been confirmed by a myriad of scientific tests. Evolution doesn't deal with spiritual beliefs or God's presence like other theories of science, such as the Copernican or germ theory of diseases.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical characteristics were predetermined to change in a gradual way, over time. This 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. 에볼루션바카라사이트 states that all species of organisms share common ancestors that can be traced by fossils and other evidence. This is the current view on evolution, and is supported by a variety of scientific fields which include molecular biology.
Scientists aren't sure how organisms have evolved however they are certain that natural selection and genetic drift is the reason for the development of life. Individuals with advantageous traits are more likely to survive and reproduce, and these individuals transmit their genes to the next generation. As time passes this leads to gradual changes to the gene pool, which eventually lead to new species and forms.
Some scientists use the term"evolution" in reference to large-scale change, such as the evolution of a species from an ancestral one. Others, like population geneticists, define evolution more broadly by referring an overall change in the frequency of alleles across generations. Both definitions are acceptable and accurate however, some scientists claim that the definition of allele frequency is lacking crucial aspects of the evolutionary process.
Origins of Life
The most important step in evolution is the development of life. The emergence of life occurs when living systems begin to evolve at a micro level, such as within cells.
The origins of life is an issue in a variety of disciplines such as biology, chemistry and geology. The origin of life is an area that is of immense interest to scientists, as it challenges the theory of evolution. It is often described as "the mystery of life," or "abiogenesis."
The idea that life could emerge 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 emergence of living organisms was not achievable through a natural process.
Many scientists still believe that it is possible to make the transition from nonliving substances to living. However, the conditions required are extremely difficult to replicate in the laboratory. This is why scientists studying the origins of life are also interested in determining the physical properties of early Earth and other planets.
Additionally, the evolution of life is dependent on a sequence of very complex chemical reactions that can't be predicted from basic physical laws alone. These include the transformation of long, information-rich molecules (DNA or RNA) into proteins that perform some function, and the replication of these intricate molecules to generate new DNA or RNA sequences. These chemical reactions can be compared to a chicken-and egg problem that is the emergence and growth of DNA/RNA, the protein-based cell machinery, is required to begin the process of becoming a living organism. But, without life, the chemistry required to enable it does appear to work.
Research in the area of abiogenesis requires cooperation among scientists from many different fields. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
The term "evolution" today is used to describe general changes in genetic traits over time. These changes may be the result of the adaptation to environmental pressures as discussed in Darwinism.
This latter mechanism increases the number of genes that confer the advantage of survival for a species, resulting in an overall change in the appearance of an entire group. The specific mechanisms responsible for these evolutionary changes include mutation, reshuffling of genes during sexual reproduction, and also gene flow between populations.
While mutation and reshuffling of genes occur in all living things The process through which beneficial mutations are more prevalent is referred to as natural selection. As mentioned above, those who possess the desirable characteristic have a higher reproduction rate than those who do not. Over the course of many generations, this differential in the numbers of offspring produced can result in a gradual shift in the average amount of desirable traits within a group of.
This can be seen in the evolution of various beak designs on finches that are found in the Galapagos Islands. They have developed these beaks in order that they can eat more easily in their new habitat. These changes in the shape and appearance of organisms can also help create new species.
The majority of the changes that occur are the result of a single mutation, but sometimes, several changes occur simultaneously. Most of these changes are neutral or even harmful to the organism, however, a small proportion of them can be beneficial to survival and reproduction, thus increasing their frequency 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 notion of evolution with the idea that traits inherited can be altered by conscious choice or by use and abuse, which is called soft inheritance. This is a misunderstanding of the nature of evolution and of the actual biological processes that cause it. A more accurate description of evolution is that it is a two-step procedure which involves the separate and often conflicting 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. The earliest human fossils show that our ancestors were bipeds, walkers with two legs. Genetic and biological similarities suggest that we are closely related to Chimpanzees. In fact, our closest relatives are the chimpanzees from the Pan genus. This includes pygmy as well as bonobos. The last common ancestor of humans and chimpanzees was 8 to 6 million years old.
Over time humans have developed a number of characteristics, including bipedalism as well as the use of fire. They also invented advanced tools. But it's only in the past 100,000 years or so that most of the important characteristics that differentiate us from other species have emerged. These include language, a large brain, the capacity to build and use complex tools, as well as the diversity of our culture.
The process of evolution occurs when genetic changes enable members of the group to better adapt to their environment. This adaptation is triggered by natural selection, a process whereby certain traits are preferred over others. The ones with the best adaptations are more likely to pass 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 says that species that share a common ancestor tend to develop similar traits over time. This is because these traits help them to reproduce and survive within their environment.
Every living thing has an molecule called DNA that holds the information necessary to direct their growth. The DNA molecule consists of base pairs arranged spirally around phosphate molecules and sugar molecules. The sequence of bases found in each strand determines the phenotype - the characteristic appearance and behavior of an individual. Variations in a population are caused by reshufflings and mutations of genetic material (known collectively as alleles).
Fossils of the first human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. While there are some differences between them they all support the notion that modern humans first appeared in Africa. The genetic and fossil evidence suggests that the first humans left Africa and moved to Asia and Europe.