The Berkeley Evolution Site
Teachers and students who browse the Berkeley site will find resources to help them understand and teach evolution. The resources are arranged into different learning paths, such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains how over time creatures that are more adaptable to changing environments do better than those that don't become extinct. Science is about this process of evolution.
What is Evolution?
The word evolution can have many nonscientific meanings. For example it could mean "progress" and "descent with modifications." Scientifically, it refers to a process of changing the characteristics of organisms (or species) over time. This change is based in biological terms on natural drift and selection.
Evolution is a fundamental concept in modern biology. It is a concept that has been tested and proven through thousands of scientific tests. In contrast to other theories in science such as the Copernican theory or the germ theory of disease, evolution does not address questions of spiritual belief or God's existence.
Early evolutionists, such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to evolve in a gradual manner over time. They referred to this as the "Ladder of Nature" or the scala naturae. Charles Lyell first used this term in 1833 in his Principles of Geology.
에볼루션 코리아 presented his theory of evolution in his book On the Origin of Species which was written in the early 1800s. It states that all species of organisms have an ancestry that can be traced by fossils and other evidence. This is the current understanding of evolution, which is supported by many research lines in science that include molecular genetics.
While scientists do not know exactly how organisms developed however they are sure that the evolution of life on earth is a result of natural selection and genetic drift. People with traits that are advantageous are more likely to live and reproduce, and they pass their genes on to the next generation. As time passes, the gene pool gradually changes and evolves into new species.
Certain scientists also use the term"evolution" to refer to large-scale evolutionary changes such as the creation of an entirely new species from an ancestral species. Other scientists, like population geneticists, define the term "evolution" more broadly by referring the net variation in the frequency of alleles over generations. Both definitions are correct and acceptable, however certain scientists argue that allele frequency definitions do not include important aspects of evolutionary process.
Origins of Life
One of the most crucial steps in evolution is the development of life. The beginning of life takes place when living systems start to develop at a microscopic level, such as within cells.
The origin of life is an important issue in many fields that include biology and chemistry. The question of how living things started has a special place in science because it is a major challenge to the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
The idea that life could be born from non-living matter was known as "spontaneous generation" or "spontaneous evolutionary". This was a popular belief prior to Louis Pasteur's tests showed that the creation of living organisms was not possible through a natural process.
Many scientists believe it is possible to go from nonliving to living substances. However, the conditions needed are extremely difficult to reproduce in labs. This is why researchers investigating the nature of life are also interested in understanding the physical properties of early Earth and other planets.
In addition, the development of life is the sequence of extremely complex chemical reactions that can't be predicted from basic physical laws alone. This includes the conversion of long, information-rich molecules (DNA or RNA) into proteins that perform a function, and the replication of these complex molecules to generate new DNA or sequences of RNA. These chemical reactions are often compared with the chicken-and-egg issue of how life first appeared: The appearance of DNA/RNA and proteins-based cell machinery is vital for the beginning of life, but without the development of life, the chemistry that makes it possible isn't working.
Abiogenesis research requires collaboration among researchers from different disciplines. This includes prebiotic chemists, the astrobiologists, the planet scientists geophysicists and geologists.
Evolutionary Changes
Today, the word evolution is used to describe general changes in genetic traits over time. These changes may result from adaptation to environmental pressures as explained in the article on Darwinism (see the entry on Charles Darwin for background), or from natural selection.
This mechanism also increases the number of genes that confer a survival advantage in a species, resulting in an overall change in the appearance of a group. The specific mechanisms that cause these evolutionary changes include mutation or reshuffling genes during sexual reproduction, and also gene flow between populations.
Natural selection is the process that makes beneficial mutations more frequent. All organisms undergo changes and reshuffles of their genes. This is because, as we've mentioned earlier those who have the beneficial trait tend to have a higher reproduction rate than those who do not have it. Over the course of several generations, this difference in the number of offspring born can result in a gradual shift in the average number of advantageous traits in a population.
This is evident in the evolution of various beak designs on finches that are found in the Galapagos Islands. They have developed these beaks so they can get food more quickly in their new home. These changes in the shape and appearance of living organisms may also be a catalyst for the creation of new species.
The majority of the changes that occur are the result of a single mutation, but occasionally several will happen at once. Most of these changes can be neutral or even harmful however, a small percentage could have a positive impact on survival and reproduce and increase their frequency over time. Natural selection is a process that can produce the accumulating change over time that leads to a new species.
Many people confuse evolution with the idea of soft inheritance, which is the idea that inherited traits can be changed through conscious choice or abuse. This is a misunderstood understanding of the nature of evolution and of the actual biological processes that lead to it. It is more precise to say that evolution is a two-step independent process, which involves the forces of natural selection as well as mutation.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, which is a group of mammal species that includes gorillas and chimpanzees. The earliest human fossils indicate that our ancestors were bipeds. They were walkers with two legs. Genetic and biological similarities suggest that we are closely related to Chimpanzees. In reality we are the closest connected to chimpanzees belonging to the Pan genus that includes pygmy and pygmy chimpanzees and bonobos. The last common human ancestor as well as chimpanzees was born between 8 and 6 million years ago.
In the course of time, humans have developed a variety of traits, including bipedalism as well as the use of fire. They also invented advanced tools. But it's only in the last 100,000 years or so that the majority of the characteristics that differentiate us from other species have developed. These include a large brain that is sophisticated and the capacity of humans to build and use tools, as well as cultural diversity.
Evolution happens when genetic changes allow individuals in a group to better adapt to their surroundings. Natural selection is the mechanism that drives this adaptation. Certain traits are preferred over others. The more adapted are more likely to pass on their genes to the next generation. This is the way that all species evolve and is the foundation of the theory of evolution.
Scientists refer to it as 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 make it easier to survive and reproduce within their environment.
Every organism has the DNA molecule, which contains the information necessary to direct their growth. 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 the phenotype, or the individual's characteristic appearance and behavior. A variety of changes and reshuffling of genetic material (known as alleles) during sexual reproduction can cause variations in a population.
Fossils from the early 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 notion that modern humans first appeared in Africa. Evidence from fossils and genetics suggest that early humans migrated out of Africa into Asia and then Europe.