The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find resources to assist them in understanding and teaching evolution. The resources are organized into various learning paths that can be used in a variety of ways, such as "What does T. rex look like?"
Charles Darwin's theory of natural selection describes how species who are better able to adapt biologically to changing environments over time, and those who do not become extinct. Science is all about this process of evolution.
What is Evolution?
The term "evolution" can be used to refer to a variety of nonscientific meanings. For example, it can mean "progress" and "descent with modifications." Scientifically, it refers to a process of change in the characteristics of living things (or species) over time. In terms of biology the change is due to natural selection and genetic drift.
Evolution is the central tenet of modern biology. It is an established theory that has stood the test of time and thousands of scientific studies. In contrast to other theories in science like the Copernican theory or the germ theory of disease, evolution does not address issues of religion or God's existence.
Early evolutionists, including Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical traits were predetermined to change, in a gradual way, over time. This was called 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 proven through fossils and other evidence. This is the current understanding of evolution, which is supported by a variety of lines of research in science which includes molecular genetics.
While scientists do not know the exact mechanism by which organisms evolved, they are confident that the evolution of life on earth is a result of natural selection and genetic drift. Individuals with advantageous traits are more likely to live and reproduce, and these individuals pass their genes on to the next generation. Over time the gene pool slowly changes and develops into new species.
Some scientists use the term evolution in reference to large-scale change, such as the development of a species from an ancestral one. Other scientists, such as population geneticists, define the term "evolution" more broadly, referring to the net change in the frequency of alleles across generations. Both definitions are acceptable and accurate however, some scientists claim that the allele-frequency definition omits crucial aspects of the evolutionary process.
Origins of Life
The emergence of life is an essential step in evolution. The beginning of life takes place when living systems start to develop at a micro level, like within individual cells.
The origins of life are an important topic in many fields such as biology and chemistry. The question of how living things got their start is of particular importance in science since it poses an enormous challenge to the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
Traditionally, the notion that life can emerge from nonliving objects is known as spontaneous generation or "spontaneous evolution." This was a common belief before Louis Pasteur's experiments proved that it was impossible for the creation of life to be a result of a purely natural process.
Many scientists still think it is possible to transition from living to nonliving substances. The conditions required to create life are difficult to reproduce in a lab. Researchers interested in the origins and evolution of life are also keen to learn about the physical characteristics of the early Earth as well as other planets.
The development of life is dependent on a variety of complex chemical reactions, which are not predicted by simple physical laws. This includes the conversion of long information-rich molecules (DNA or RNA) into proteins that carry out functions, and the replication of these complex molecules to generate new DNA or RNA sequences. These chemical reactions are often compared with the chicken-and-egg problem of how life first appeared: The development of DNA/RNA as well as protein-based cell machinery is essential for the beginning of life, however, without the emergence of life, the chemistry that makes it possible is not working.
Abiogenesis research requires collaboration with scientists from different fields. This includes prebiotic scientists, astrobiologists, and planetary scientists.
Evolutionary Changes
Today, the word evolution is used to describe the general changes in genetic traits over time. These changes may result from the response to environmental pressures as discussed in the entry on Darwinism (see the entry on Charles Darwin for background) or natural selection.
This latter mechanism increases the number of genes that confer a survival advantage in an animal, resulting in an overall change in the appearance of a group. The specific mechanisms behind these evolutionary changes are mutation and reshuffling of genes in sexual reproduction, as well as gene flow between populations.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo changes and reshuffles of their genes. This happens because, as noted above those who have the beneficial trait tend to have a higher reproduction rate than those without it. Over the course of several generations, this differential in the numbers of offspring produced can result in gradual changes in the number of beneficial traits within a group of.
This is evident in the evolution of different beak designs on finches that are found in the Galapagos Islands. They have developed these beaks in order that they can access food more easily in their new environment. These changes in form and shape can also help create new organisms.
The majority of changes are caused by a single mutation, but sometimes several occur at once. Most of these changes can be neutral or even harmful however, a few can have a beneficial impact on the survival of the species and reproduce with increasing frequency as time passes. Natural selection is a process that can produce the accumulating change over time that eventually leads to a new species.
Some people confuse the idea of evolution with the idea that inherited characteristics can be changed through conscious choice, or through use and abuse, which is called soft inheritance. This is a misunderstanding of the biological processes that lead to the process of evolution. A more accurate description of evolution is that it is a two-step procedure that involves the distinct and often conflicting forces of mutation and natural selection.
Origins of Humans
Modern humans (Homo sapiens) evolved from primates - a species of mammals that includes gorillas, chimpanzees, and bonobos. The earliest human fossils show that our ancestors were bipeds - walkers with two legs. Genetic and biological similarities suggest that we are closely related to the chimpanzees. In reality our closest relatives are the chimpanzees from the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor shared between humans and chimpanzees was between 8 and 6 million years old.
Over time humans have developed a variety of traits, including bipedalism and the use of fire. They also invented 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 emerged. These include language, large brain, the capacity to create and utilize sophisticated tools, and a cultural diversity.
Evolution occurs when genetic changes allow members of a population to better adapt to their environment. This adaptation is driven by natural selection, a process whereby certain traits are preferred over others. click homepage who are better adapted are more likely to pass on their genes to the next generation. This is how all species evolve and the basis of the theory of evolution.
Scientists refer to it as the "law of Natural Selection." The law states that species which share an ancestor will tend to develop similar traits in the course of time. This is because those traits allow them to survive and reproduce in their environment.
Every organism has the DNA molecule, which contains the information needed to guide their growth. The DNA structure is composed of base pair 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. Variations in a population are caused by mutations and reshufflings in genetic material (known collectively as alleles).
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. Despite some differences the fossils all support the notion that modern humans first appeared in Africa. The genetic and fossil evidence suggests that the first humans left Africa and moved to Asia and Europe.