The Berkeley Evolution Site
The Berkeley site contains resources that can assist students and teachers to understand and teach about evolution. The materials are organized in various learning paths that can be used in a variety of ways like "What does T. rex look like?"
Charles Darwin's theory on natural selection describes how species that are better equipped to adapt biologically to changing environments survive longer and those that do not end up becoming extinct. Science is about this process of biological evolution.
What is Evolution?
The term "evolution" has a variety of nonscientific meanings, including "progress" or "descent with modification." Scientifically, it refers to a changes in the traits of living organisms (or species) over time. In biological terms, this change is caused by natural selection and genetic drift.
Evolution is a fundamental concept in modern biology. It is a concept that has been tested and verified by a myriad of scientific tests. It does not address spiritual beliefs or God's presence in the same way as 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 characteristics were predetermined to change in a step-like fashion over time. This was known 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 published in the early 1800s. It asserts that different species of organisms have the same ancestry, which can be traced through fossils and other evidence. This is the current view on evolution, and is supported in a wide range of scientific fields that include molecular biology.
While scientists don't know the exact mechanism by which organisms evolved, they are confident that the evolution of life on earth is a result of natural selection and genetic drift. People with advantages are more likely than others to live and reproduce. These individuals then pass their genes on to the next generation. As time passes the gene pool slowly changes and evolves into new species.
Some scientists use the term evolution in reference to large-scale changes, such the development of a species from an ancestral one. Other scientists, such as population geneticists, define the term "evolution" more broadly, referring to a net change in allele frequencies over generations. Both definitions are valid and reliable however some scientists believe that the allele-frequency definition omits essential aspects of the evolution process.
Origins of Life
One of the most crucial steps in evolution is the emergence of life. The emergence of life occurs when living systems begin to develop at a micro level, such as within individual cells.
The origins of life are an important subject in many areas, including biology and the field of chemistry. The origin of life is a subject of great interest in science because it is a challenge to the theory of evolution. It is sometimes referred to as "the mystery" of life or "abiogenesis."
Traditionally, the belief that life can emerge from nonliving things is called spontaneous generation or "spontaneous evolution." 에볼루션 룰렛 was a popular view before Louis Pasteur's experiments proved that it was impossible for the creation of life to happen through an entirely natural process.
Many scientists believe it is possible to transition from living to nonliving substances. The conditions needed to create life are difficult to replicate in a laboratory. Researchers studying the nature of life are also interested in determining the physical properties of early Earth and other planets.
The development of life is dependent on a variety of complex chemical reactions, that are not predicted by basic physical laws. These include the reading of long, information-rich molecules (DNA or RNA) into proteins that carry out some function and the replication of these intricate molecules to generate new DNA or sequences of RNA. These chemical reactions are often compared with the chicken-and-egg problem of how life first appeared: The appearance of DNA/RNA and proteins-based cell machinery is vital for the onset of life, but without the development of life, the chemical reaction that is the basis for it does not appear to work.
Research in the area of abiogenesis requires collaboration between scientists from many different disciplines. This includes prebiotic chemists, the astrobiologists, the planet scientists, geologists and geophysicists.
Evolutionary Changes
The term "evolution" is commonly used today to refer to the accumulated changes in the genetic characteristics of populations over time. These changes can result from the response to environmental pressures as explained in the article on Darwinism (see the entry on Charles Darwin for background), or from natural selection.
This mechanism also increases the frequency of genes that offer an advantage for survival in a species, resulting in an overall change in the appearance of the group. These evolutionary changes are triggered by mutations, reshuffling genes during sexual reproduction and gene flow.
Natural selection is the process that allows beneficial mutations to become more common. All organisms undergo mutations and reshuffles of their genes. This is because, as noted above those who have the advantageous trait are likely to have a higher reproduction rate than those without it. This differential in the number of offspring born over many generations can cause a gradual change in the average number advantageous traits in the group.
This is evident in the evolution of different beak designs on finches that are found in the Galapagos Islands. They have developed these beaks so that they can eat more easily in their new habitat. These changes in shape and form could aid in the creation of new organisms.
The majority of changes are caused by a single mutation, however sometimes multiple occur simultaneously. Most of these changes can be neutral or even harmful, but a small number can have a beneficial impact on survival and reproduction and increase their frequency as time passes. Natural selection is a process that could result in the accumulation of changes over time that lead to a new species.
Many people mistakenly associate evolution with the concept of soft inheritance, which is the idea that traits inherited from parents can be changed through conscious choice or abuse. This is a misunderstanding of the biological processes that lead up to evolution. A more precise description is that evolution involves a two-step process, that involves the distinct and often conflicting forces of mutation and natural selection.
Origins of Humans
Modern humans (Homo sapiens) evolved from primates - a group of mammals that also includes chimpanzees and gorillas and bonobos. Our ancestors walked on two legs, as demonstrated by the earliest fossils. 에볼루션 슬롯 and biological similarities suggest that we are closely related to chimpanzees. In reality we are the most closely connected to chimpanzees belonging to the Pan Genus, which includes bonobos and pygmy chimpanzees. The last common ancestor between modern humans and chimpanzees was between 8 and 6 million years old.
Over time humans have developed a range of characteristics, including bipedalism and the use fire. They also invented advanced tools. However, it is only in the past 100,000 years or so that the majority of the important characteristics that differentiate us from other species have been developed. These include language, a large brain, the capacity to create and utilize complex tools, as well as the ability to adapt to cultural differences.
The process of evolution occurs when genetic changes allow members of a population to better adapt to their surroundings. This adaptation is driven by natural selection, which is a process by which certain traits are favored over other traits. The ones who are better adapted are more likely to pass their genes on to the next generation. This is the way all species evolve and is the basis of the theory of evolution.
Scientists refer to this as the "law of natural selection." The law states that species that have a common ancestor are more likely to develop similar characteristics over time. This is because these traits make it easier for them to live and reproduce in their environments.
All organisms have a DNA molecule that contains the information needed to guide their growth and development. The DNA structure is composed of base pair which are arranged in a spiral, around sugar and phosphate molecules. The sequence of bases within each string determines the phenotype or the characteristic appearance and behavior of an individual. 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, as well as Homo neanderthalensis have been found in Africa, Asia and Europe. Despite some differences they all support the hypothesis that modern humans first came into existence in Africa. The fossil evidence and genetic evidence suggest that early humans moved from Africa into Asia and then Europe.