The Berkeley Evolution Site
The Berkeley site contains resources that can assist students and teachers learn about and teach evolution. The materials are organized into optional learning paths such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection states that over time, animals that are better able to adapt biologically to changing environments survive and those that do not become extinct. Science is about this process of evolution.
What is Evolution?
The word evolution has many nonscientific meanings, such as "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. In terms of biology the change is caused by natural selection and genetic drift.
Evolution is an important tenet in the field of biology today. It is a theory that has been proven by thousands of scientific tests. Evolution does not deal with spiritual beliefs or God's presence like other scientific theories such as 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 gradual manner over time. This was referred to 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.
Darwin presented his theory of evolution in his book On the Origin of Species, written in the early 1800s. It asserts that different species of organisms share a common ancestry, which can be determined through fossils and other lines of evidence. This is the current perspective on evolution, which is supported in a wide range of disciplines, including molecular biology.
While scientists don't know exactly how organisms evolved but they are certain that the evolution of life on earth is a result of natural selection and genetic drift. People with traits that are advantageous are more likely to live and reproduce, and these individuals transmit their genes to the next generation. Over time, this results in gradual changes to the gene pool, which eventually result in new species and types.
Some scientists also use the term"evolution" to describe large-scale evolutionary changes, such as the formation of an entirely new species from an ancestral species. Others, like population geneticists, define the term "evolution" more broadly by referring an overall change in allele frequencies over generations. Both definitions are accurate and acceptable, however some scientists believe that allele-frequency definitions do not include important aspects of evolution.
Origins of Life
The most important step in evolution is the development of life. This happens when living systems begin to develop at the micro level, within individual cells, for instance.
The origins of life are an issue in a variety of disciplines, including geology, chemistry, biology and chemistry. The nature of life is a topic that is of immense interest to scientists, as it challenges the theory of evolution. It is often referred to as "the mystery of life," or "abiogenesis."
Traditionally, the belief that life can arise from nonliving things 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 emergence of life to occur by an entirely natural process.
Many scientists still believe that it is possible to transition from nonliving substances to life. The conditions required to create life are difficult to replicate in a laboratory. Researchers interested in the origins and development of life are also eager to know the physical properties of the early Earth as well as other planets.
In addition, the development 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 transformation of long information-rich molecules (DNA or RNA) into proteins that perform a function and the replication of these complex molecules to generate new DNA or RNA sequences. These chemical reactions are often compared to the chicken-and-egg dilemma of how life first appeared: The appearance of DNA/RNA and proteins-based cell machinery is vital for the beginning of life, but without the emergence of life, the chemical process that allows it does not appear to work.
Abiogenesis research requires collaboration with scientists from various fields. This includes prebiotic chemists, planet scientists, astrobiologists, geologists and geophysicists.
Evolutionary Changes
The term "evolution" is used to describe gradual changes in genetic traits over time. These changes can result from adaptation to environmental pressures as explained in the article on Darwinism (see the entry on Charles Darwin for background) or natural selection.
This is a process that increases the frequency of those genes in a species which confer an advantage in survival over others and causes gradual changes in the overall appearance of a population. These evolutionary changes are triggered by mutations, reshuffling genes during sexual reproduction and the flow of genes.
While reshuffling and mutations of genes happen in all living organisms and the process by which beneficial mutations become more common is known as natural selection. This is because, as noted above those with the beneficial trait tend to have a higher fertility rate than those who do not have it. This differential in the number of offspring born over a long period of time can cause a gradual change in the average number advantageous characteristics in a group.
visit the next internet site is the increase in beak size on different species of finches in the Galapagos Islands, which have evolved different shaped beaks that allow them to easily access food in their new habitat. These changes in the shape and appearance of living organisms may also be a catalyst for the creation of new species.
The majority of the changes that occur are the result of one mutation, but occasionally, multiple mutations occur at the same time. Most of these changes can be harmful or neutral however, a small percentage can have a beneficial impact on survival and reproduction, increasing their frequency over time. Natural selection is a process that could result in the accumulation of changes over time that lead to a new species.
Some people mistakenly associate evolution with the concept of soft inheritance that is the belief that traits inherited from parents can be altered by conscious choice or abuse. This is a misunderstanding of the biological processes that lead up to evolution. A more accurate description is that evolution involves a two-step process, which involves the separate and often conflicting 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. Our predecessors walked on two legs, as demonstrated by the earliest fossils. Genetic and biological similarities suggest that we share the same ancestry with the chimpanzees. In actual fact we are the most closely with chimpanzees in the Pan Genus that includes pygmy and bonobos and pygmy chimpanzees. The last common human ancestor as well as chimpanzees lived between 8 and 6 million years ago.
Humans have developed a range of traits throughout time such as bipedalism, use of fire, and the development of advanced tools. However, it is only in the past 100,000 years or so that most of the traits that distinguish us from other species have been developed. They include a huge, complex brain and the capacity of humans to construct and use tools, as well as cultural variety.
Evolution occurs when genetic changes allow individuals in a group to better adapt to their environment. This adaptation is triggered by natural selection, a process that determines certain traits are more desirable than other traits. The ones who are better adapted are more likely to pass their genes on to the next generation. This is the way that all species evolve and is the foundation of the theory of evolution.
Scientists call it the "law of natural selection." The law states species that share an ancestor will tend to acquire similar traits over time. It is because these traits make it easier to reproduce and survive within their environment.
Every living thing has DNA molecules, which contains the information needed to direct their growth and development. The structure of DNA is composed of base pairs which are arranged in a spiral, around sugar and phosphate molecules. The sequence of bases within each strand determines phenotype, or the individual's characteristic appearance and behavior. Variations in a population are caused by mutations and reshufflings of genetic material (known collectively as alleles).
Fossils from the earliest human species, Homo erectus and Homo neanderthalensis, have been found in Africa, Asia, and Europe. These fossils, despite differences in their appearance all support the theory of modern humans' origins in Africa. The genetic and fossil evidence suggests that early humans left Africa and migrated to Asia and Europe.