The Berkeley Evolution Site
The Berkeley site contains resources that can help students and teachers understand and teach evolution. The materials are arranged in different learning paths like "What does T. rex look like?"
Charles Darwin's theory on natural selection explains how animals who are better able to adapt biologically to a changing environment survive over time and those who do not disappear. Science is concerned with this process of evolutionary change.
What is Evolution?
The term "evolution" can have many nonscientific meanings. For instance "progress" or "descent with modification." Scientifically, it is a term used to describe a changing the characteristics of organisms (or species) over time. In terms of biology the change is based on natural selection and genetic drift.
에볼루션 슬롯게임 is a fundamental concept in the field of biology today. It is a concept that has been verified by a myriad of scientific tests. Evolution doesn't deal with the existence of God or religious beliefs like other scientific theories such as the Copernican or germ theory of disease.
Early evolutionists, such as Erasmus Darwin (Charles’s grandfather) and Jean-Baptiste Lamarck believed that certain physical characteristics were predetermined to change in a stepped-like 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 published in the early 1800s. It claims that different species of organisms share a common ancestry, which can be proven through fossils and other lines of evidence. This is the modern view on evolution, which is supported by a variety of disciplines that include molecular biology.
Scientists don't know the evolution of organisms however they are certain that natural selection and genetic drift is responsible for the development of life. Individuals with advantageous characteristics are more likely than others to live and reproduce. They transmit their genes to the next generation. Over time, this results in gradual changes to the gene pool which gradually result in new species and forms.
Some scientists use the term"evolution" to refer to large-scale changes, like the formation of a species from an ancestral one. Some scientists, like population geneticists, define evolution in a broad sense, using the term "net change" to refer to the variation in the frequency of alleles over generations. Both definitions are correct and acceptable, but some scientists argue that allele-frequency definitions miss important aspects of the evolution.
Origins of Life
The birth of life is an essential step in the process of evolution. This happens when living systems begin to evolve at the micro level - within cells, for instance.
The origins of life are an issue in a variety of disciplines that include biology, chemistry and geology. The question of how living things started is a major topic in science because it is an enormous challenge to the theory of evolution. It is often referred to "the mystery" of life or "abiogenesis."
The notion that life could be born from non-living things was called "spontaneous generation" or "spontaneous evolutionary". It was a popular belief before Louis Pasteur's tests proved that the emergence of living organisms was not possible by the natural process.
Many scientists still believe it is possible to go from nonliving substances to life. The conditions required to create life are difficult to replicate in a laboratory. This is why scientists investigating the beginnings of life are also interested in understanding the physical properties of early Earth and other planets.
Additionally, the evolution of life is dependent on an intricate sequence of chemical reactions that can't be predicted based on basic physical laws alone. These include the reading of long, information-rich molecules (DNA or RNA) into proteins that carry out a function as well as the replication of these intricate molecules to create new DNA or RNA sequences. These chemical reactions are often compared to the chicken-and-egg dilemma of how life first appeared in the first place. The appearance of DNA/RNA and protein-based cell machinery is crucial to the birth of life, but without the emergence of life, the chemistry that makes it possible is not working.
Abiogenesis research requires collaboration between scientists from various fields. This includes prebiotic scientists, astrobiologists and planet scientists.
Evolutionary Changes
The word evolution is usually used today to describe the cumulative changes in genetic characteristics of populations over time. These changes can result from adaptation to environmental pressures, as described in the entry on Darwinism (see the entry on Charles Darwin for background), or from natural selection.
The latter is a mechanism that increases the frequency of those genes in a species that confer an advantage in survival over others and causes gradual changes in the appearance of a population. The specific mechanisms responsible for these evolutionary changes are mutation, reshuffling of genes during sexual reproduction, as well as gene flow between populations.
While mutation and reshuffling of genes happen in all organisms, the process by which beneficial mutations are more prevalent is known as natural selection. This is because, as mentioned above, those individuals with the beneficial trait tend to have a higher reproduction rate than those who do not have it. This variation in the number of offspring that are produced over a number of generations could result in a gradual change in the average number of beneficial traits within the group.
This is evident in the evolution of various beak shapes on finches from the Galapagos Islands. They have developed these beaks in order that they can access food more easily in their new habitat. These changes in shape and form could also help create new organisms.
The majority of changes are caused by one mutation, although sometimes multiple occur simultaneously. Most of these changes can be neutral or even harmful however, a small percentage could have a positive impact on survival and reproduction and increase their frequency as time passes. This is the mechanism of natural selection and it is able to eventually result in the accumulating changes that eventually result in the creation of a new species.
Many 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 misinterpretation of the biological processes that lead to the process of evolution. It is more accurate to say that evolution is a two-step, separate process, that is influenced by the forces of natural selection and mutation.
Origins of Humans
Humans today (Homo sapiens) evolved from primates, a group of mammals that includes gorillas, chimpanzees, and bonobos. Our ancestors walked on two legs, as evidenced by the earliest fossils. Genetic and biological similarities suggest that we are closely related to Chimpanzees. In reality we are the closest related to the chimpanzees within the Pan Genus, which includes bonobos and pygmy-chimpanzees. The last common ancestor of humans and chimpanzees was 8 to 6 million years old.
Humans have developed a range 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 language, a large brain, the ability to construct and use complex tools, and the ability to adapt to cultural differences.
Evolution occurs when genetic changes allow individuals of a population to better adapt to their environment. This adaptation is driven by natural selection, a process that determines certain traits are favored over other traits. The better adaptable are more likely to pass on their genes to the next generation. This is how all species evolve, and it is the basis of the theory of evolution.
Scientists call it the "law of Natural Selection." The law states species that have a common ancestor are likely to develop similar characteristics in the course of time. It is because these traits allow them to reproduce and survive within their environment.
All organisms have a DNA molecule, which contains the information needed to control their growth and development. The DNA molecule consists of base pairs that are arranged in a spiral around phosphate molecules and sugar molecules. The sequence of bases in each strand determines the phenotype - the distinctive appearance and behavior of a person. Variations in a population are caused by mutations and reshufflings in genetic material (known collectively as alleles).
Fossils from the early human species Homo erectus and Homo neanderthalensis have been discovered in Africa, Asia and Europe. These fossils, despite a few differences in their appearance all support the theory of modern humans' origins in Africa. Evidence from fossils and genetics suggest that early humans moved from Africa into Asia and then Europe.