The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find a wealth of resources to help them understand and teach evolution. The materials are organized in different learning paths, such as "What does T. rex look like?"
Charles Darwin's theory of natural selection explains that in time, creatures better able to adapt biologically to changing environments do better than those that don't become extinct. This process of evolution in biology is the basis of science.
What is Evolution?
The term "evolution" can have many nonscientific meanings. For instance "progress" or "descent with modification." It is a scientific term that is used to describe the process of change of characteristics over time in organisms or species. This change is based in biological terms on natural selection and drift.
Evolution is a fundamental concept in modern biology. It is an accepted theory that has stood the test of time and a multitude of scientific experiments. Contrary to other theories of 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 like Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to evolve in a step-like fashion over time. This was known as 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 asserts that all species of organisms share a common ancestry which can be traced through fossils and other evidence. This is the current understanding of evolution that is supported by many lines of scientific research which includes molecular genetics.
Scientists aren't sure the evolution of organisms however they are certain that natural selection and genetic drift are the primary reason for the evolution of life. People with desirable traits are more likely to live and reproduce, and they pass their genes on to the next generation. In time this leads to a gradual accumulation of changes to the gene pool, which eventually lead to new species and forms.
Some scientists employ the term"evolution" to refer to large-scale changes, such the development of a species from an ancestral one. Some scientists, like 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 valid and reliable however, some scientists claim that the allele-frequency definition is missing essential aspects of the evolution process.
Origins of Life
The emergence of life is an essential stage in evolution. This happens when living systems begin to evolve at a micro-level - within individual cells, for instance.
The origins of life is a topic in many disciplines that include geology, chemistry, biology and chemistry. The origin of life is a subject of great interest in science, as it is a challenge to the theory of evolution. It is often referred to as "the mystery of life" or "abiogenesis."
Traditionally, 에볼루션 룰렛 that life can arise from nonliving objects is known as spontaneous generation or "spontaneous evolution." This was a popular view before Louis Pasteur's experiments proved that it was impossible for the emergence of life to happen through an entirely natural process.
Many scientists believe it is possible to go from nonliving to living substances. However, the conditions that are required are extremely difficult to replicate in labs. Researchers interested in the origins and evolution of life are also keen to understand the physical properties of the early Earth as well as other planets.
The growth of life is also dependent on a series of complex chemical reactions that are not predicted by simple physical laws. These include the transformation of long, information-rich molecules (DNA or RNA) into proteins that carry out functions, and the replication of these complex molecules to produce 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 to begin the process of becoming a living organism. However without life, the chemistry needed to create it is working.
Research in the field of abiogenesis requires collaboration among scientists from many different disciplines. This includes prebiotic chemists, astrobiologists, planetary scientists, geologists and geophysicists.
Evolutionary Changes
The term "evolution" is used to describe cumulative changes in genetic characteristics over time. These changes can result from the response 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 is a method that increases the frequency of genes in a species that confer an advantage in survival over others and causes an ongoing change in the overall appearance of a group. These changes in evolutionary patterns are caused by mutations, reshuffling genes during sexual reproduction and gene flow.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo changes and reshuffles in their genes. This is because, as we've mentioned earlier those who have the advantageous trait are likely to have a higher reproductive rate than those without it. Over many generations, this variation in the number of offspring produced can result in a gradual shift in the average amount of desirable traits within a group of.
A good example of this is the growing beak size on different species of finches found on the Galapagos Islands, which have developed different beak shapes to allow them to more easily access food in their new habitat. These changes in the shape and form of organisms can also aid in the creation of new species.
The majority of the changes that occur are the result of one mutation, however occasionally several will happen at the same time. Most of these changes are neither harmful nor even harmful to the organism, however a small portion of them could have a positive impact on the survival of the organism and its reproduction, thereby increasing the frequency of these changes in the population over time. Natural selection is a process that can produce the accumulating change over time that leads to the creation of a new species.
Some people think that evolution is a form of soft inheritance that is the belief that traits inherited from parents can be changed by deliberate choice or misuse. This is a misunderstanding of the nature of evolution, and of the actual biological processes that cause it. It is more accurate to say that evolution is a two-step independent process that involves the forces of natural selection as well as mutation.
Origins of Humans
Humans of today (Homo sapiens) evolved from primates, a group of mammals that includes gorillas, chimpanzees, and bonobos. Our predecessors walked on two legs, as demonstrated by the first fossils. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In reality we are the most closely related to the chimpanzees within the Pan genus, which includes bonobos and pygmy chimpanzees. The last common ancestor of modern humans and chimpanzees was born between 8 and 6 million years ago.
As time has passed, humans have developed a number of traits, including bipedalism and the use of fire. They also created advanced tools. It's only within the last 100,000 years that we have developed the majority of our important characteristics. They include language, a large brain, the ability to create and utilize complex tools, and the diversity of our culture.
Evolution happens when genetic changes allow members of a population to better adapt to their surroundings. This adaptation is driven by natural selection, a process whereby certain traits are favored over other traits. The better adjusted are more likely to pass on their genes to the next generation. This is the way that all species evolve and forms the basis of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species which share a common ancestor tend to develop similar traits over time. This is because the traits make it easier for them to survive and reproduce in their natural environment.
All organisms possess a DNA molecule that contains the information needed to control their growth. The DNA molecule is made up of base pairs that are spirally arranged around sugar molecules and phosphate molecules. The sequence of bases in each string determines the phenotype or the appearance and behavior of a person. Different changes and reshuffling of genetic material (known as alleles) during sexual reproduction cause variation in a group.
Fossils from the earliest human species Homo erectus, as well as Homo neanderthalensis have been discovered in Africa, Asia and Europe. These fossils, despite differences in their appearance all support the hypothesis of the origins of modern humans in Africa. Evidence from fossils and genetics suggest that early humans came from Africa into Asia and then Europe.