The Berkeley Evolution Site
Teachers and students who visit the Berkeley site will find a wealth of resources to assist them in understanding and teaching evolution. The materials are arranged in optional learning paths for example "What does T. rex look like?"
Charles Darwin's theory of natural selection explains that in time, creatures more adaptable to changing environments thrive, and those that don't become extinct. Science is all about this process of biological evolutionary change.
What is Evolution?
The term "evolution Kr" can have many nonscientific meanings, such as "progress" or "descent with modification." Scientifically, it refers to a process of changes in the traits of living organisms (or species) over time. This change is based in biological terms on natural selection and drift.
Evolution is a central tenet of modern biology. It is an established theory that has withstood the test of time and a multitude of scientific experiments. It does not address God's presence or spiritual beliefs, unlike many other scientific theories such as the Copernican or germ theory of diseases.
Early evolutionists like Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical traits were predetermined to change in a gradual manner over time. They called this the "Ladder of Nature" or the scala naturae. Charles Lyell used the term to describe this concept in his Principles of Geology, first published in 1833.
Darwin presented his theory of evolution in his book On the Origin of Species which was written in the early 1800s. It asserts that different species of organisms have a common ancestry, which can be proven through fossils and other lines of evidence. This is the current view of evolution, and is supported by numerous lines of research in science, including molecular genetics.
Scientists don't know the evolution of organisms, but they are confident that natural selection and genetic drift is the primary reason for the evolution of life. Individuals with advantageous characteristics are more likely to live and reproduce. They transmit their genes to the next generation. In time this leads to an accumulation of changes to the gene pool that gradually lead to new species and forms.
Some scientists also use the term"evolution" to describe large-scale evolutionary changes, such as the formation of a new species from an ancestral species. Certain scientists, including population geneticists define evolution in a broader sense by using the term "net change" to refer to the change in allele frequency over generations. Both definitions are acceptable and accurate however some scientists believe that the definition of allele frequency is lacking important features of the evolutionary process.
Origins of Life
The development of life is an essential stage in evolution. This happens when living systems begin to evolve at a micro-level - within individual cells, for example.
The origins of life are an important subject in many areas, including biology and the field of chemistry. The nature of life is a subject that is of immense interest to scientists because it challenges the theory of evolution. It is sometimes referred to as "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 popular view before Louis Pasteur's experiments showed that it was impossible for the development of life to be a result of a purely natural process.
Many scientists still think it is possible to move from nonliving substances to living ones. However, the conditions required are extremely difficult to replicate in labs. This is why researchers studying the beginnings of life are also interested in understanding the physical properties of the early Earth and other planets.
Additionally, the evolution of life depends on the sequence of extremely complex chemical reactions that can't be predicted from the fundamental physical laws on their own. These include the reading and the replication of complex molecules, such as DNA or RNA, to produce proteins that serve a specific function. These chemical reactions are often compared with the chicken-and-egg issue of how life began: The appearance of DNA/RNA and protein-based cell machinery is crucial for the beginning of life, but without the development of life, the chemical reaction that is the basis for it isn't working.
Abiogenesis research requires collaboration with scientists from various disciplines. This includes prebiotic scientists, astrobiologists and planetary scientists.
Evolutionary Changes
The term "evolution" today is used to describe gradual changes in genetic traits over time. These changes could be the result of the adaptation to environmental pressures as explained in Darwinism.
This is a method that increases the frequency of genes in a species which confer an advantage in survival over others and causes an ongoing change in the overall appearance of a group. These evolutionary changes are triggered by mutations, reshuffling of genes during sexual reproduction, and the flow of genes.
Natural selection is the process that makes beneficial mutations more common. All organisms undergo changes and reshuffles of genes. As previously mentioned, those who have the advantageous characteristic have a higher reproduction rate than those who do not. Over the course of many generations, this differential in the numbers of offspring born can result in an inclination towards a shift in the number of advantageous characteristics in a particular population.
A good example of this is the increase in beak size on different species of finches found on the Galapagos Islands, which have developed different beak shapes that allow them to easily access food in their new habitat. These changes in the form and shape of organisms could also aid in the creation of new species.
The majority of the changes that occur are caused by one mutation, however occasionally several will happen at once. Most of these changes may be harmful or neutral however, a small percentage could have a positive impact on survival and reproduction, increasing their frequency over time. This is the process of natural selection, and it could, over time, produce the cumulative changes that eventually result in an entirely new species.
Some people think that evolution is a form of soft inheritance which is the notion that inherited traits can be changed by conscious choice or abuse. This is a misunderstood understanding of the nature of evolution, and of the actual biological processes that cause it. A more precise description is that evolution is a two-step procedure that involves the distinct and often conflicting forces of mutation and natural selection.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, a species of mammal species which includes chimpanzees as well as gorillas. The earliest human fossils prove that our ancestors were bipeds. They were walkers with two legs. Genetic and biological similarities show that we share the same ancestry with chimpanzees. In fact, our closest relatives are the chimpanzees from the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor shared between modern humans and chimpanzees dated 8 to 6 million years old.
Humans have evolved a variety of characteristics over time such as bipedalism, use of fire and advanced tools. It's only within the last 100,000 years that we have developed the majority of our key characteristics. These include a big, complex brain and the capacity of humans to build and use tools, as well as cultural diversity.
Evolution occurs when genetic changes allow members of a population to better adapt to their surroundings. This adaptation is driven by natural selection, a process that determines certain traits are more desirable than other traits. The more adapted are more likely to pass on their genes to the next generation. This is the process that evolves all species, and it is the foundation of the theory of evolution.
Scientists call it the "law of Natural Selection." The law states that species that have an ancestor in common will tend to develop similar traits as time passes. This is because those characteristics make it easier for them to survive and reproduce in their environments.
Every living thing has a DNA molecule, which provides the information necessary to direct their growth and development. The DNA molecule is made up of base pairs arranged spirally around sugar molecules and phosphate molecules. The sequence of bases in each string determines the phenotype or the characteristic appearance and behavior of an individual. Variations in a population can be caused by reshufflings and mutations of genetic material (known collectively as alleles).
Fossils of the first human species, Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia, and Europe. These fossils, despite differences in their appearance, all support the hypothesis of modern humans' origins in Africa. The fossil evidence and genetic evidence suggest that early humans moved out of Africa into Asia and then Europe.