The Berkeley Evolution Site
Teachers and students who browse the Berkeley site will find a wealth of resources to aid in understanding and teaching evolution. The materials are organized into a variety of learning paths like "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains how animals who are better able to adapt biologically to changing environments survive longer and those that don't become extinct. This process of biological evolution is the main focus of science.
What is Evolution?
The word evolution has many nonscientific meanings, including "progress" or "descent with modification." Scientifically it is a term used to describe a changes in the traits of living things (or species) over time. This change is based in biological terms on natural drift and selection.
Evolution is one of the fundamental tenets of modern biology. It is a theory that has been tested and confirmed by a myriad of scientific tests. Unlike many other scientific theories like the Copernican theory or the germ theory of disease, the evolution theory does not address questions of religion or God's existence.
Early evolutionists, including Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather), believed that certain physical characteristics were predetermined to change in a gradual manner, over time. They called this 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 an ancestry that can be traced through fossils and other evidence. This is the current perspective on evolution, and is supported by a variety of areas of science, including molecular biology.
Although scientists aren't able to determine exactly how organisms developed, they are confident that the evolution of life on earth is a result of natural selection and genetic drift. Individuals with advantageous characteristics are more likely to survive and reproduce. They then pass their genes on to the next generation. As time passes this leads to a gradual accumulation of changes to the gene pool, which eventually create new species and forms.
Some scientists also employ the term"evolution" to describe large-scale evolutionary changes like the creation of an entirely new species from an ancestral species. Certain scientists, including population geneticists, define evolution in a broad sense, talking about the net variation in the frequency of alleles over generations. Both definitions are valid and reliable however, some scientists claim that the definition of allele frequency is lacking important features of the evolutionary process.
Origins of Life
The development of life is an essential step in the process of evolution. The emergence of life occurs when living systems start to evolve at a micro level, such as within individual cells.
The origin of life is a topic in many disciplines, including biology, chemistry and geology. The question of how living things started is of particular importance in science because it is a major challenge to the theory of evolution. It is often referred to as "the mystery of life," or "abiogenesis."
The idea that life could be born from non-living things was called "spontaneous generation" or "spontaneous evolutionary". This was a popular belief prior to Louis Pasteur's experiments proved that the creation of living organisms was not achievable through a natural process.
Many scientists still believe that it is possible to make the transition from nonliving materials to living. However, the conditions required are extremely difficult to replicate in labs. This is why researchers studying the nature of life are also interested in understanding 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 can't be predicted from the fundamental 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 generate new DNA or sequences of RNA. These chemical reactions are often compared with the chicken-and-egg dilemma of how life came into existence in the first place. The development of DNA/RNA as well as protein-based cell machinery is essential for the onset of life, but without the appearance of life, the chemistry that makes it possible does not appear to work.
Research in the field of abiogenesis requires collaboration among scientists from various disciplines. This includes prebiotic scientists, astrobiologists and planet scientists.
Evolutionary Changes
The term "evolution" is typically used today to refer to the accumulated changes in the genetic traits of an entire population over time. These changes may be the result of the adaptation to environmental pressures as explained in Darwinism.
This is a method that increases the frequency of genes that confer an advantage in survival over others which results in a gradual change in the appearance of a group. The specific mechanisms that cause these evolutionary changes are mutation, reshuffling of genes during sexual reproduction, as well as gene flow between populations.
While reshuffling and mutations of genes are common in all living things The process through which beneficial mutations are more prevalent is referred to as natural selection. As mentioned above, those who have the advantageous trait have a higher reproductive rate than those who don't. This difference in the number of offspring produced over a number of generations could cause a gradual change in the average number advantageous characteristics in the group.
This can be seen in the evolution of different beak shapes for finches from the Galapagos Islands. They have created these beaks to ensure that they can access food more easily in their new habitat. These changes in the form and shape of organisms could also aid in the creation of new species.
Most of the changes that occur are caused by one mutation, however sometimes, several changes occur at once. The majority of these changes could be harmful or neutral, but a small number may have a positive effect on survival and reproduce, increasing their frequency over time. This is the process of natural selection, and it can, over time, produce the accumulating changes that ultimately lead to the creation of a new species.
Some people confuse evolution with the idea of soft inheritance which is the notion that traits inherited from parents can be altered by conscious choice or abuse. This is a misunderstanding of the biological processes that lead to the process of evolution. 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
Modern humans (Homo sapiens) evolved from primates, a group of mammals that includes chimpanzees, gorillas, and bonobos. Our predecessors walked on two legs, as shown by the oldest fossils. Genetic and biological similarities show that we have a close relationship with Chimpanzees. In reality our closest relatives are chimpanzees belonging to the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor of modern humans and chimpanzees was between 8 and 6 million years old.
Over time, humans have developed a range of traits, including bipedalism as well as the use of fire. They also invented advanced tools. It is only in the past 100,000 years or so that most of the important traits that distinguish us from other species have been developed. They include language, a large brain, the ability to build and use complex tools, and cultural diversity.
Evolution happens when genetic changes allow individuals in a group to better adapt to their environment. This adaptation is driven by natural selection, a process that determines certain traits are favored over 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 forms the basis of the theory of evolution.
Our Site refer to it as the "law of natural selection." The law states that species which have an ancestor in common will tend to develop similar characteristics in the course of time. This is because those characteristics make it easier for them to survive and reproduce in their natural environment.
All organisms have DNA molecules, which provides the information necessary to direct their growth and development. The structure of DNA is composed of base pair that are arranged in a spiral around phosphate and sugar molecules. The sequence of bases within each strand determines phenotype or the individual's unique appearance and behavior. Variations in a population can be caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils of the first human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. These fossils, despite variations in their appearance, all support the idea of the origins of modern humans in Africa. The genetic and fossil evidence suggests that the first humans left Africa and moved to Asia and Europe.