The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find a wealth of resources to assist them in understanding and teaching evolution. The materials are organized into optional learning paths, such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection describes how species that are better equipped to adapt biologically to a changing environments survive longer and those who do not become extinct. This process of biological evolution is the main focus of science.
What is Evolution?
The term "evolution" could be used to refer to a variety of nonscientific meanings. For instance, it can mean "progress" and "descent with modifications." Scientifically it refers to a changing the characteristics of living organisms (or species) over time. In biological terms, this change is due to natural selection and genetic drift.
Evolution is one of the fundamental tenets of modern biology. It is a theory that has been tested and verified by thousands of scientific tests. Unlike many other scientific theories, 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 Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical traits were predetermined to change in a step-like way, over time. This was called 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. It states that all species of organisms have a common ancestry, which can be proven through fossils and other lines of evidence. This is the modern view of evolution, which is supported by many lines of research in science which includes molecular genetics.
While scientists do not know exactly how organisms developed but they are certain that the evolution of life on earth is a result of natural selection and genetic drift. Individuals with advantageous traits are more likely to live and reproduce, and they transmit their genes to the next generation. In time, this results in an accumulation of changes to the gene pool that gradually lead to new species and forms.
Some scientists use the term"evolution" in reference to large-scale changes, like the development of an animal from an ancestral one. Other scientists, such as population geneticists, define it more broadly by referring a net change in the frequency of alleles across generations. Both definitions are valid and reliable however some scientists believe that the allele-frequency definition is missing important features of the evolutionary process.
Origins of Life
One of the most crucial steps in evolution is the appearance of life. This occurs when living systems begin to evolve at a 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 an area of interest in science, as it is a challenge to the theory of evolution. It is often called "the mystery of life" or "abiogenesis."
Traditionally, the notion that life can emerge from nonliving objects is known as spontaneous generation, or "spontaneous evolution." This was a popular view before Louis Pasteur's research showed that it was impossible for the creation of life to be a result of a purely natural process.
Many scientists believe that it is possible to make the transition from nonliving substances to living. The conditions necessary for the creation of life are difficult to replicate in a laboratory. This is why scientists investigating the beginnings of life are also keen to understand the physical properties of early Earth and other planets.
In addition, the development of life depends on a sequence of very complex chemical reactions that cannot be predicted from basic physical laws on their own. This includes the conversion of long, information-rich molecules (DNA or RNA) into proteins that perform a function and the replication of these intricate molecules to create new DNA or sequences of RNA. These chemical reactions are comparable to a chicken-and egg problem which is the development and emergence of DNA/RNA, the protein-based cell machinery, is essential for the onset life. Although without life, the chemistry that is required to make it possible does appear to work.
Research in the field of abiogenesis requires collaboration between scientists from a variety of disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
The word evolution is usually used to describe the cumulative changes in the genetic characteristics of populations over time. These changes could be the result of adapting to environmental pressures, as described in Darwinism.
This mechanism also increases the frequency of genes that offer an advantage for survival in the species, leading to an overall change in the appearance of the group. The specific mechanisms that cause these evolutionary changes include mutation and reshuffling of genes in sexual reproduction, and gene flow between populations.
Natural selection is the process that makes beneficial mutations more common. All organisms undergo mutations and reshuffles of genes. As mentioned above, those who possess the desirable trait have a higher reproduction rate than those who don't. This difference in the number of offspring produced over many generations can result in a gradual change in the average number advantageous traits within a group.
An excellent example is the growing the size of the beaks on different species of finches on the Galapagos Islands, which have evolved different shaped beaks to enable them to more easily access food in their new home. These changes in shape and form could aid in the creation of new organisms.
Most of the changes that take place are the result of one mutation, however occasionally several will happen at once. The majority of these changes are not harmful or even detrimental to the organism, but a small percentage can have a positive impact on survival and reproduction, thus increasing their frequency in the population over time. This is the process of natural selection and it could, over time, produce the cumulative changes that eventually result in a 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 by conscious choice or abuse. This is a misunderstanding of the biological processes that lead up to the process of evolution. A more accurate description is that evolution is a two-step procedure involving the independent, and often competing, forces of mutation and natural selection.
Origins of Humans
Humans of today (Homo sapiens) evolved from primates - a species of mammals that includes chimpanzees, gorillas, and bonobos. The earliest human fossils indicate that our ancestors were bipeds - walkers on two legs. Genetic and biological similarities show that we share an intimate relationship with Chimpanzees. In reality, our closest relatives are the chimpanzees from the Pan genus. This includes pygmy and bonobos. The last common human ancestor and chimpanzees was born 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 in the last 100,000 years or so that the majority of the essential traits that distinguish us from other species have been developed. They include a huge, complex brain, the ability of humans to create and use tools, as well as cultural diversity.
Evolution occurs when genetic changes allow members of the group to better adapt to their environment. Natural selection is the process that drives this change. Certain characteristics are more desirable than others. The more adaptable are more likely to pass their genes on to the next generation. This is how all species evolve and is the foundation of the theory of evolution.
Scientists call this the "law of natural selection." The law states species that have a common ancestor are likely to develop similar characteristics in the course of time. It is because these traits make it easier to survive and reproduce within their environment.
Every living thing has a DNA molecule that is the source of information that helps guide their growth and development. The DNA structure is made of base pairs arranged in a spiral around sugar and phosphate molecules. The sequence of bases within each strand determines phenotype which is the person's distinctive appearance and behavior. The variations in a population are caused by mutations and reshufflings in genetic material (known collectively as alleles).
Fossils from the earliest human species Homo erectus, as well as Homo neanderthalensis have been discovered in Africa, Asia and Europe. Although there are some differences the fossils all support the hypothesis that modern humans first appeared in Africa. 에볼루션 카지노 and fossil evidence also suggest that early humans migrated out of Africa into Asia and then Europe.