The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find a wealth of resources to help them understand and teach evolution. The materials are arranged into different learning paths like "What did T. rex taste like?"
Charles Darwin's theory of natural selection states that over time, animals that are more able to adapt to changing environments thrive, and those that do not become extinct. This process of biological evolution is the main focus of science.
What is Evolution?
The word evolution has many nonscientific meanings, including "progress" or "descent with modification." It is scientifically based and refers to the process of change of characteristics over time in organisms or species. In biological terms, this change is caused by natural selection and genetic drift.
Evolution is a fundamental concept in the field of biology today. It is a well-supported theory that has withstood the tests of time and thousands of scientific experiments. Evolution does not deal with God's presence or spiritual beliefs, unlike many other theories in science, like the Copernican or germ theory of disease.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical characteristics were predetermined to change, in a step-wise manner, as time passes. This was called the "Ladder of Nature" or scala naturae. Charles Lyell first used this term in 1833 in his Principles of Geology.
Darwin presented his theory of evolution in his book On the Origin of Species, written in the early 1800s. It asserts that different species of organisms have a common ancestry, which can be proven through fossils and other evidence. This is the current perspective of evolution, which is supported in many scientific fields which include molecular biology.
Although scientists aren't able to determine exactly how organisms developed, they are confident that the evolution of life on earth is a result of natural selection and genetic drift. Individuals with advantageous traits are more likely to survive and reproduce, and these individuals transmit their genes to the next generation. Over time this leads to gradual changes in the gene pool which gradually result in new species and types.
Certain scientists also use the term evolution to refer to large-scale evolutionary changes, such as the formation of a new species from an ancestral species. 에볼루션 카지노 사이트 , including population geneticists, define the term "evolution" in a broad sense, referring to the net change in the frequency of alleles across generations. Both definitions are accurate and acceptable, but some scientists argue that allele-frequency definitions do not include important aspects of evolutionary process.
Origins of Life
The development of life is a key step in the process of evolution. This happens when living systems begin to develop at the micro level, within cells, for example.
The origins of life is an issue in a variety of disciplines such as biology, chemistry, and geology. The origin of life is a topic of great interest in science, as it is a challenge to the theory of evolution. It is sometimes referred to "the mystery" of life or "abiogenesis."
The notion that life could arise from non-living objects was referred to as "spontaneous generation" or "spontaneous evolutionary". This was a popular belief prior to Louis Pasteur's tests showed that the emergence of living organisms was not possible by the natural process.
Many scientists still think it is possible to transition from living to nonliving substances. However, the conditions needed are extremely difficult to replicate in a laboratory. Researchers who are interested in the origins and development of life are also eager to understand the physical properties of the early Earth as well as other planets.
The life-cycle of a living organism is dependent on a number of complex chemical reactions, which cannot be predicted by basic physical laws. This includes the conversion 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 sequences of RNA. These chemical reactions are comparable to a chicken-and egg problem: the emergence and development of DNA/RNA, protein-based cell machinery, is essential to begin the process of becoming a living organism. Although without life, the chemistry that is required to make it possible does appear to work.
Research in the area of abiogenesis requires collaboration among scientists from many different disciplines. This includes prebiotic scientists, astrobiologists and planet scientists.
Evolutionary Changes
The word evolution is usually used to describe the accumulated changes in genetic characteristics of an entire population 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 from natural selection.
This latter mechanism increases the number of genes that provide an advantage for survival in the species, leading to an overall change in the appearance of an entire group. These evolutionary changes are triggered by mutations, reshuffling genes in the process of sexual reproduction, and also by the flow of genes.
Natural selection is the process that makes beneficial mutations more common. All organisms undergo mutations and reshuffles of their genes. As mentioned above, those who possess the desirable trait have a higher reproductive rate than those that do not. Over many generations, this differential in the number of offspring born could result in an inclination towards a shift in the number of advantageous traits within a group of.
An excellent example is the growth of beak size on various species of finches in the Galapagos Islands, which have evolved different shaped beaks that allow them to easily access food in their new environment. These changes in the shape and form of organisms can also help create new species.
The majority of changes are caused by one mutation, but sometimes several occur at once. The majority of these changes could be harmful or neutral however, a small percentage could have a positive impact on survival and reproduce, increasing their frequency over time. Natural selection is a process that could result in the accumulation of changes over time that lead to a new species.
Some people confuse the idea of evolution with the notion that the traits inherited from parents can be altered by conscious choice or use and abuse, a concept known as soft inheritance. This is a misunderstanding of the biological processes that lead to evolution. A more accurate description of evolution is that it is a two-step process involving the independent and often conflicting forces of natural selection and mutation.
Origins of Humans
Humans today (Homo sapiens) evolved from primates, a group of mammals that also includes gorillas, chimpanzees, 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 belonging to the Pan genus. This includes pygmy and bonobos. The last common human ancestor as well as chimpanzees was between 8 and 6 million years ago.
Humans have developed a range of characteristics over time including bipedalism, the use of fire, and the development of advanced tools. It is only within the last 100,000 years that we have developed the majority of our important characteristics. These include language, a large brain, the ability to build and use complex tools, and the ability to adapt to cultural differences.
Evolution happens when genetic changes allow individuals in a group to better adapt to their surroundings. Natural selection is the mechanism that triggers this adaptation. Certain characteristics are more desirable than others. The more adjusted are more likely to pass their genes on to the next generation. This is how all species evolve and is the basis of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states species that have a common ancestor are likely to develop similar characteristics as time passes. This is because these traits allow them to reproduce and survive within their environment.
Every organism has the DNA molecule, which contains the information needed to control their growth. The DNA structure is made of base pairs that are arranged in a spiral around sugar and phosphate molecules. The sequence of bases within each strand determines the phenotype, or the individual's characteristic appearance and behavior. Variations in a population can be 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 found in Africa, Asia and Europe. While there are some differences between them, 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.