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The Berkeley Evolution Site

Teachers and students who visit the Berkeley site will find resources to help them understand evolutionkr and teach evolution. The resources are organized into optional learning paths such as "What did T. rex taste like?"

Charles Darwin's theory of natural selection explains that in time, creatures better able to adapt biologically to changing environments thrive, and those that don't become extinct. Science is concerned with this process of evolution.

What is Evolution?

The word evolution has many nonscientific meanings, including "progress" or "descent with modification." Scientifically it refers to a changing the characteristics of living things (or species) over time. In terms of biology, this change is caused by natural selection and genetic drift.

Evolution is the central tenet of modern biology. It is a concept that has been proven through thousands of scientific tests. Contrary to other theories of science, such as the Copernican theory or the germ theory of disease, evolution is not a discussion of spiritual belief or God's existence.

Early evolutionists, such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to change in a step-like fashion 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 states that all species of organisms have the same ancestry, which can be traced through fossils and other evidence. This is the current view 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 is the primary reason for the development of life. Individuals with advantageous characteristics are more likely to survive and reproduce. They pass on their genes to the next generation. In time, this results in gradual changes to the gene pool which gradually result in new species and types.

Some scientists use the term"evolution" to refer to large-scale changes, like the formation of an animal from an ancestral one. Other scientists, like population geneticists, define it more broadly, referring to an overall change in allele frequencies over generations. Both definitions are valid and acceptable, however some scientists believe that allele-frequency definitions omit important features of evolutionary process.

Origins of Life

The development of life is a crucial stage in evolution. This happens when living systems begin to evolve at a micro-level - within cells, for instance.

The origins of life are an important issue in a variety of fields, including biology and chemistry. The origin of life is an area of interest in science, as it is a challenge to the theory of evolution. It is sometimes referred to as "the mystery" of life or "abiogenesis."

Traditionally, the notion that life can arise from nonliving objects is known as spontaneous generation or "spontaneous evolution." This was a common belief before Louis Pasteur's research showed that it was impossible for the emergence of life to occur by an entirely natural process.

Many scientists believe it is possible to move from nonliving to living substances. However, the conditions needed are extremely difficult to reproduce in the laboratory. Researchers interested in the evolution and origins of life are also keen to learn about the physical characteristics of the early Earth as well as other planets.

The life-cycle of a living organism is also dependent on a series of complex chemical reactions which are not predicted by basic physical laws. These include the reading of long, information-rich molecules (DNA or RNA) into proteins that carry out a function and the replication of these complex molecules to create new DNA or sequences of RNA. These chemical reactions are often compared with the chicken-and-egg dilemma of how life first appeared with the development of DNA/RNA as well as protein-based cell machinery is crucial for the onset of life, but without the appearance of life the chemistry that makes it possible does not appear to work.

Abiogenesis research requires collaboration between scientists from various fields. This includes prebiotic scientists, astrobiologists, and planet scientists.

Evolutionary Changes

The term "evolution" is typically used today to describe the accumulated changes in the genetic characteristics of an entire population over time. These changes could be the result of the adaptation to environmental pressures as explained in Darwinism.

The latter is a mechanism that increases the frequency of genes which confer an advantage in survival over other species and causes gradual changes in the overall appearance of a group. These changes in evolutionary patterns are caused by mutations, reshuffling genes during sexual reproduction, and gene flow.

While reshuffling and mutations of genes are common in all living organisms and the process by which beneficial mutations are more frequent is called natural selection. This is because, as we've mentioned earlier those who have the beneficial trait tend to have a higher reproductive rate than those without it. Over the course of several generations, this difference in the number of offspring produced can result in a gradual 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 beaks with different shapes to enable them to more easily access food in their new home. These changes in shape and form can aid in the creation of new organisms.

The majority of changes are caused by a single mutation, although sometimes multiple occur at the same time. The majority of these changes could be neutral or even harmful, but a small number may have a positive effect on survival and reproduce and increase their frequency over time. This is the mechanism of natural selection and it can be a time-consuming process that produces the gradual changes that eventually result in the creation of 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, a concept called soft inheritance. This is a misunderstood understanding of the nature of evolution, and of the actual biological processes that lead to it. It is more precise to say that evolution is a two-step independent process that involves the forces of natural selection and mutation.

Origins of Humans

Modern humans (Homo Sapiens) evolved from primates, which is a group of mammal species which includes gorillas and chimpanzees. The earliest human fossils prove that our ancestors were bipeds. They were walking on two legs. Genetic and biological similarities suggest that we are closely related to Chimpanzees. In fact our closest relatives are the 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 ago.

Over time, humans have developed a variety of characteristics, such as bipedalism and the use fire. They also developed advanced tools. However, it is only in the last 100,000 years or so that the majority of the traits that distinguish us from other species have developed. These include a big brain that is sophisticated, the ability of humans to create and use tools, and cultural variety.

The process of evolution occurs when genetic changes allow members of a population to better adapt to their surroundings. Natural selection is the process that triggers this adaptation. Certain characteristics are more desirable than others. The ones who are better adaptable are more likely to pass on their genes to the next generation. This is how all species evolve and forms the foundation of the theory of evolution.

Scientists call it the "law of Natural Selection." The law states that species which have an ancestor in common will tend to develop similar traits in the course of time. This is because these traits help them to reproduce and survive within their environment.

Every organism has a DNA molecule that contains the information necessary to direct their growth. The structure of DNA is composed of base pair that are arranged in a spiral around phosphate and sugar molecules. The sequence of bases in each strand determines the phenotype, the appearance and behavior of a person. Variations in changes and reshuffling of genetic material (known as alleles) during reproduction causes variation in a population.

Fossils from the earliest human species Homo erectus, as well as Homo neanderthalensis have been discovered in Africa, Asia and Europe. These fossils, despite a few variations in their appearance, all support the theory that modern humans' ancestors originated in Africa. The genetic and fossil evidence suggests that early humans left Africa and moved to Asia and Europe.