The Berkeley Evolution Site
The Berkeley site has resources that can help students and teachers to understand and teach about evolution. The resources are organized into optional learning paths, such as "What does T. rex look like?"
Charles Darwin's theory of natural selection describes how species who are better able to adapt to changes in their environment survive over time and those that do not end up becoming extinct. Science is all about this process of biological evolution.
What is Evolution?
The term "evolution" can have a variety of meanings that are not scientific. For example it could refer to "progress" and "descent with modifications." Scientifically it refers to a change in the characteristics of living things (or species) over time. The reason for this change is biological terms on natural drift and selection.
Evolution is the central tenet of modern biology. It is a theory that has been confirmed by thousands of scientific tests. It does not address the existence of God or religious beliefs like other theories in science, like the Copernican or germ theory of diseases.
Early evolutionists such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to evolve in a stepped-like manner over time. They referred to this as the "Ladder of Nature" or scala naturae. Charles Lyell used the term to describe this idea in his Principles of Geology, first published in 1833.
In the early 1800s, Darwin formulated his theory of evolution and published it in his book On the Origin of Species. It asserts that all species of organisms share a common ancestry which can be traced through fossils and other evidence. This is the current view of evolution, which is supported by numerous research lines in science which includes molecular genetics.
Scientists don't know how organisms evolved however they are certain that natural selection and genetic drift are the reason for the evolution of life. People with advantages are more likely to survive and reproduce. They then pass their genes to the next generation. Over time the gene pool gradually changes and evolves into new species.
Some scientists also use the term evolution to refer to large-scale evolutionary changes, such as the formation of the new species from an ancestral species. Others, like population geneticists, define the term "evolution" more broadly by referring to an overall change in allele frequencies over generations. Both definitions are valid and reliable, although some scientists argue that the allele-frequency definition is missing crucial aspects of the evolutionary process.
Origins of Life
The birth of life is an essential step in the process of evolution. The emergence of life occurs when living systems begin to evolve at a micro scale, for instance within cells.
The origin of life is an important subject in a variety of disciplines that include biology and chemistry. The question of how living organisms began has a special place in science since it poses an important challenge to the theory of evolution. 에볼루션코리아 is sometimes referred to as "the mystery" of life or "abiogenesis."
Traditionally, the belief that life can arise from nonliving things is called 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 occur by an entirely natural process.
Many scientists believe it is possible to transition from nonliving to living substances. However, the conditions that are required are extremely difficult to reproduce in the laboratory. This is why researchers investigating the beginnings of life are also keen to understand the physical properties of the early Earth and other planets.
The growth of life is also dependent on a series of complex chemical reactions, which cannot be predicted by simple physical laws. This includes the conversion of long information-rich molecules (DNA or RNA) into proteins that perform a function as well as the replication of these intricate molecules to create new DNA or RNA sequences. These chemical reactions are often compared with the chicken-and-egg issue of how life began: The development of DNA/RNA as well as protein-based cell machinery is essential for the onset of life, however, without the appearance of life, the chemical reaction that is the basis for it does not appear to work.
에볼루션코리아 in the area of abiogenesis requires collaboration among scientists from a variety of disciplines. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
The term "evolution" is used to describe the gradual changes in genetic traits over time. These changes may result from adaptation to environmental pressures as described in the entry on Darwinism (see the entry on Charles Darwin for background) or may result from natural selection.
This process increases the frequency of genes that provide a survival advantage in an animal, resulting in an overall change in the appearance of the group. These changes in evolutionary patterns are caused by mutations, reshuffling of genes in the process of sexual reproduction, and also by the flow of genes.
Natural selection is the process that makes beneficial mutations more frequent. All organisms undergo mutations and reshuffles of genes. As noted above, individuals who have the advantageous trait have a higher reproductive rate than those who don't. Over the course of many generations, this differential in the number of offspring born could result in a gradual shift in the amount of desirable characteristics in a particular population.
An excellent example is the growth of beak size on different species of finches on the Galapagos Islands, which have developed beaks with different shapes that allow them to easily access food in their new environment. These changes in the shape and appearance of living organisms may also aid in the creation of new species.
The majority of changes are caused by a single mutation, although 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 have a positive impact on survival and reproduction, thus increasing their frequency in the population over time. Natural selection is a process that causes the accumulating change over time that eventually leads to a new species.
Some people confuse the idea of evolution with the idea that the traits inherited from parents can be changed through conscious choice or use and abuse, which is known as soft inheritance. This is a misunderstanding of the biological processes that lead up to evolution. A more accurate description is that evolution is a two-step procedure that involves the distinct and often antagonistic forces of natural selection and mutation.
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. The earliest human fossils prove that our ancestors were bipeds - walkers with two legs. Biological and genetic similarities indicate that we have the same ancestry with the chimpanzees. In reality we are the most closely connected to chimpanzees belonging to the Pan genus, which includes bonobos and pygmy chimpanzees. The last common ancestor of humans and chimpanzees was 8 to 6 million years old.
Humans have evolved a wide range of characteristics over time including bipedalism, the use of fire and advanced tools. It is only in the last 100,000 years or so that the majority of the important traits that distinguish us from other species have been developed. They include a huge brain that is sophisticated, the ability of humans to create and use tools, and cultural diversity.
Evolution happens when genetic changes allow members of a population to better adapt to their surroundings. Natural selection is the process that drives this adaptation. Certain characteristics are more desirable than others. The ones with the best adaptations are more likely to pass their genes to the next generation. This is how 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 have a common ancestor are more likely to develop similar characteristics over time. This is because these characteristics make it easier for them to survive and reproduce in their environments.
Every living thing has the DNA molecule, which contains the information needed to guide their growth. The structure of DNA is composed of base pair 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. The variations in a population are caused by mutations and reshufflings in genetic material (known collectively as alleles).
Fossils of the earliest human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. Although there are some differences, these fossils all support the idea that modern humans first came into existence in Africa. Genetic and fossil evidence also suggest that early humans migrated out of Africa into Asia and then Europe.