The Berkeley Evolution Site
The Berkeley site offers resources that can help students and educators to understand and teach about 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, animals that are better able to adapt biologically to changing environments survive and those that do not become extinct. Science is concerned with the process of biological evolution.
What is Evolution?
The term "evolution" can have many nonscientific meanings. For instance "progress" or "descent with modification." It is scientifically based and is used to describe the process of changing characteristics in a species or species. In biological terms the change is due to natural selection and genetic drift.
Evolution is one of the fundamental tenets of modern biology. It is a well-supported theory that has stood the test of time and thousands of scientific experiments. Evolution doesn't deal with spiritual beliefs or God's presence in the same way as other scientific theories such as the Copernican or germ theory of diseases.
Early evolutionists, such as 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 known as the "Ladder of Nature", or scala Naturae. Charles Lyell first used this term in 1833 in his Principles of Geology.
Darwin published his theory of evolution in his book On the Origin of Species which was written in the early 1800s. It claims that different species of organisms have an ancestry that can be determined through fossils and other evidence. This is the current view of evolution, which is supported by a variety of lines of research in science, including molecular genetics.
Scientists do not know how organisms have evolved, but they are confident that natural selection and genetic drift is the primary reason for the development of life. People with desirable traits are more likely to live and reproduce, and they transmit their genes to the next generation. Over time this leads to an accumulation of changes to the gene pool which gradually lead to new species and types.
Some scientists also employ the term evolution to refer to large-scale changes in evolutionary processes such as the creation of the new species from an ancestral species. Certain scientists, including population geneticists, define the term "evolution" in a broad sense, using the term "net change" to refer to the change in allele frequency over generations. Both definitions are acceptable and accurate however some scientists believe that the allele-frequency definition omits important features of the evolutionary process.
Origins of Life
The emergence of life is an essential step in the process of evolution. This occurs when living systems begin to develop at a micro-level - within cells, for example.
The origin of life is a topic in many disciplines that include biology, chemistry, and geology. The nature of life is a subject that is of immense interest to scientists, as it is a challenge to the theory of evolution. It is often referred to as "the mystery of life," or "abiogenesis."
The idea that life could emerge from non-living things was called "spontaneous generation" or "spontaneous evolutionary". It was a common belief prior to Louis Pasteur's tests showed that the creation of living organisms was not possible through a natural process.
Many scientists still believe it is possible to transition from nonliving substances to life. The conditions needed to make life are not easy to replicate in a laboratory. Researchers interested in the origins and evolution of life are also eager to know the physical properties of the early Earth as well as other planets.
Additionally, the evolution of life is the sequence of extremely complex chemical reactions that can't be predicted based on basic physical laws on their own. This includes the conversion of long, information-rich molecules (DNA or RNA) into proteins that carry out some function, and the replication of these complex molecules to produce new DNA or RNA sequences. These chemical reactions are comparable to the chicken-and-egg problem which is the development and emergence of DNA/RNA, the protein-based cell machinery, is required to begin the process of becoming a living organism. Although, without life, the chemistry that is required to enable it does appear to work.
Research in the area of abiogenesis requires collaboration between scientists from various disciplines. This includes prebiotic chemists astrobiologists, planetary scientists, geologists and geophysicists.
Evolutionary Changes
The term "evolution" today is used to describe the gradual changes in genetic traits over time. These changes could result from the response to environmental pressures as described in the entry on Darwinism (see the entry on Charles Darwin for background), or from natural selection.
This is a method that increases the frequency of those genes which confer an advantage in survival over others, resulting in gradual changes in the overall appearance of a population. 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 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 reproductive rate than those that do not. This difference in the number of offspring that are produced over a number of generations could result in a gradual change in the average number of beneficial traits in a group.
This is evident in the evolution of various beak shapes on finches from the Galapagos Islands. They have developed these beaks in order that they can access food more easily in their new habitat. These changes in the shape and appearance of organisms can also be a catalyst for the creation of new species.
The majority of changes are caused by a single mutation, however sometimes multiple occur at the same time. The majority of these changes are neutral or even harmful to the organism however, a small proportion of them can be beneficial to the survival of the organism and its reproduction, thereby increasing the frequency of these changes in the population over time. This is the way of natural selection and it is able to be a time-consuming process that produces the gradual changes that ultimately lead to an entirely new species.
Many people confuse the concept of evolution with the notion that traits inherited can be altered by conscious choice or use and abuse, a notion called soft inheritance. This is a misinterpretation of the nature of evolution, and of the actual biological processes that cause it. 에볼루션사이트 is that evolution involves a two-step process, involving the independent and often antagonistic forces of mutation and natural selection.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, which is a group of mammal species which includes chimpanzees as well as gorillas. Our ancestors walked on two legs, as evidenced by the earliest fossils. Genetic and biological similarities suggest that we share a close relationship with Chimpanzees. In actual fact, we are most closely with chimpanzees in the Pan genus which includes bonobos and pygmy chimpanzees. The last common human ancestor and chimpanzees was born between 8 and 6 million years ago.
As time has passed, humans have developed a variety of characteristics, 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 essential characteristics that differentiate us from other species have been developed. These include a big, complex brain human ability to create and use tools, and cultural variety.
The process of evolution occurs when genetic changes enable members of the group to better adapt to the environment. Natural selection is the mechanism that triggers this adaptation. Certain traits are preferred over others. The more adjusted are more likely to pass their genes on to the next generation. This is how all species evolve and forms the basis of the theory of evolution.
Scientists call this the "law of natural selection." The law states that species that have an ancestor in common will tend to acquire similar traits in the course of time. This is because these traits allow them to survive and reproduce within their environment.
Every living thing has a DNA molecule, which provides the information necessary to guide their growth and development. The DNA molecule is made up of base pairs that are spirally arranged around sugar molecules and phosphate molecules. The sequence of bases within each strand determines the phenotype, or the individual's characteristic appearance and behavior. A variety of changes and reshuffling of genetic material (known as alleles) during reproduction causes variation in a group.
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia, and Europe. While there are some differences between them the fossils all support the hypothesis that modern humans first appeared in Africa. The fossil evidence and genetic evidence suggest that early humans came from Africa into Asia and then Europe.