The Berkeley Evolution Site
Students and teachers who explore the Berkeley site will find a wealth of resources to aid in understanding and teaching evolution. The materials are arranged into different learning paths such as "What did T. rex taste like?"
Charles Darwin's theory of natural selection explains how creatures that are better equipped to adapt biologically to a changing environments over time, and those that do not become extinct. This process of evolution is the main focus of science.
What is Evolution?
The term "evolution" can be used to refer to a variety of nonscientific meanings. For example it could refer to "progress" and "descent with modifications." It is an academic term that refers to the process of change of characteristics in a species or species. This change is based in biological terms on natural selection and drift.
Evolution is a fundamental concept in the field of biology today. It is a concept that has been confirmed by a myriad of scientific tests. In contrast to other theories in science like the Copernican theory or the germ theory of disease, the evolution theory does not address issues of religion or the existence of God.
Early evolutionists, like Jean-Baptiste Lamarck and Erasmus Darwin (Charles's grandfather) believed that certain physical traits were predetermined to change in a step-like manner, over time. This was referred to as the "Ladder of Nature" or scala naturae. Charles Lyell used the term to describe this concept in his Principles of Geology, first published in 1833.
Darwin published his theory of evolution in his book On the Origin of Species, written in the early 1800s. It states that all species of organisms share a common ancestry, which can be proven through fossils and other lines of evidence. This is the current perspective on evolution, and is supported in many disciplines which include molecular biology.
While scientists don't know exactly how organisms evolved however they are sure that the evolution of life on earth is the 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. As Going On this page passes the gene pool slowly changes and develops into new species.
Certain scientists use the term"evolution" to refer to large-scale change, such as the evolution of an animal from an ancestral one. Other scientists, such as population geneticists, define evolution more broadly by referring a net change in the frequency of alleles across generations. Both definitions are correct and acceptable, but some scientists argue that allele-frequency definitions miss important aspects of the evolutionary process.
Origins of Life
The birth of life is a crucial step in evolution. This occurs when living systems begin to evolve at the micro level, within individual cells, for example.
The origins of life are a topic in many disciplines, including biology, chemistry and geology. The question of how living things started 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 belief that life can arise from nonliving things 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 the 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. Researchers investigating the nature of life are also keen to understand the physical properties of early Earth and other planets.
Additionally, the evolution of life is a sequence of very complex chemical reactions that can't be predicted based on basic physical laws on their own. This includes the conversion of long, information-rich molecules (DNA or RNA) into proteins that perform functions, and the replication of these complex molecules to generate new DNA or RNA sequences. These chemical reactions can be compared with a chicken-and egg problem which is the development and emergence of DNA/RNA, the protein-based cell machinery, is necessary to begin the process of becoming a living organism. Although, without life, the chemistry that is required to create it does appear to work.
Research in the field of abiogenesis requires cooperation among scientists from various disciplines. This includes prebiotic chemists, planet scientists, astrobiologists, geologists and geophysicists.
Evolutionary Changes
The word evolution is usually used today to describe the accumulated changes in the genetic characteristics of populations over time. These changes could 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 mechanism also increases the frequency of genes that provide an advantage for survival in the species, leading to an overall change in the appearance of the group. The specific mechanisms behind these evolutionary changes are mutation, reshuffling of genes during sexual reproduction, and gene flow between populations.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo changes and reshuffles in their genes. This occurs because, as we've mentioned earlier those who have the beneficial trait tend to have a higher reproductive rate than those with it. This difference in the number of offspring produced over a number of generations could result in a gradual shift in the number of advantageous traits within the group.
One good example is the growth of beak size on different species of finches on the Galapagos Islands, which have evolved different shaped beaks to allow them to more easily access food in their new environment. These changes in the shape and form of organisms could also aid in the creation of new species.
Most of the changes that occur are the result of one mutation, however sometimes, several changes occur simultaneously. Most of these changes are neither harmful nor even harmful to the organism, but a small percentage can have an advantageous impact on survival and reproduction, thus increasing their frequency in the population over time. This is the way of natural selection and it could, over time, produce the cumulative changes that eventually lead to an entirely new species.
Some people mistakenly associate evolution with the concept of soft inheritance which is the notion that inherited traits can be altered by conscious choice or abuse. This is a misunderstanding of the nature of evolution, and of the actual biological processes that lead to it. A more accurate description of evolution is that it involves a two-step process, involving the independent, and often competing, forces of natural selection and mutation.
Origins of Humans
Humans of today (Homo Sapiens) evolved from primates, a group of mammal species which includes gorillas and chimpanzees. Our ancestors walked on two legs, as demonstrated by the earliest fossils. Biological and genetic similarities indicate that we have the same ancestry with Chimpanzees. In fact, our closest relatives are chimpanzees from the Pan genus. This includes pygmy, as well as bonobos. The last common ancestor between humans and chimpanzees was between 8 and 6 million years old.
In the course of time humans have developed a range of characteristics, including bipedalism and the use fire. They also developed advanced tools. But it's only in the past 100,000 years or so that most of the essential characteristics that differentiate us from other species have emerged. They include a huge, complex brain, the ability of humans to construct and use tools, as well as the diversity of our culture.
The process of evolution occurs when genetic changes allow members of the group to better adapt to the environment. This adaptation is triggered by natural selection, a process that determines certain traits are favored over other traits. 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 foundation of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species which share a common ancestor tend to develop similar traits over time. This is because these traits make it easier to live and reproduce in their environment.
Every living thing has the DNA molecule, which contains the information needed to control their growth. The DNA structure is composed of base pair which are arranged in a spiral, around sugar and phosphate molecules. The sequence of bases in each strand determines the phenotype - the characteristic appearance and behavior of a person. The variations in a population are caused by mutations and reshufflings in genetic material (known collectively as alleles).
Fossils of the earliest human species, Homo erectus and Homo neanderthalensis were discovered in Africa, Asia, and Europe. While there are some differences between them the fossils all support the idea that modern humans first appeared in Africa. Genetic and fossil evidence also suggest that early humans moved out of Africa into Asia and then Europe.