Darwin's general theory presumes the development of life from non-life and stresses a purely naturalistic undirected "descent with modification". That is, complex creatures evolve from more simplistic ancestors naturally over time. In a nutshell, as random genetic mutations occur within an organism's genetic code, the beneficial mutations are preserved because they aid survival -- a process known as "natural selection.
Charles Darwin was a British naturalist who proposed the theory of biological evolution by natural selection. Darwin defined evolution as "descent with modification," the idea that species change over time, give rise to new species, and share a common ancestor.
The mechanism that Darwin proposed for evolution is natural selection. Because resources are limited in nature, organisms with heritable traits that favor survival and reproduction will tend to leave more offspring than their peers, causing the traits to increase in frequency over generations.
Natural selection causes populations to become adapted, or increasingly well-suited, to their environments over time. Natural selection depends on the environment and requires existing heritable variation in a group.
The basic idea of biological evolution is that populations and species of organisms change over time.
Today, when we think of evolution, we are likely to link this idea with one specific person: In the s, Darwin wrote an influential and controversial book called On the Origin of Species. In it, he proposed that species evolve or, as he put it, undergo "descent with modification"and that all living things can trace their descent to a common ancestor.
For instance, all humans belong to the same species, Homo sapiens. Domestic dogs are also a species, Canis familiaris. Darwin also suggested a mechanism for evolution: For instance, eye color is a heritable trait: You can substitute the phrase "genetically determined" for "heritable" in this article if that makes more sense to you.
In this article, we'll take a closer look at Darwin's ideas. We'll trace how they emerged from his worldwide travels on the ship HMS Beagle, and we'll also walk through an example of how evolution by natural selection can work.
In fact, even some of the ancient Greek philosophers had evolutionary ideas. However, Plato among the most famous of these philosophers believed that species were fixed and unchanging, and his viewpoint was very influential in Western thought for centuries after his death.
Evolutionary ideas began to make a comeback in the eighteenth century. In the early nineteenth century, the French naturalist Jean-Baptiste Lamarck published a book proposing that evolution took place and suggesting a mechanism by which it might occur.
Specifically, Lamarck proposed that modifications in an individual caused by its environment, or the use or disuse of a structure during its lifetime, could be inherited by its offspring and lead to a change in a species.
For instance, Lamarck suggested that giraffes have long necks because some of them stretched their necks during their lifetimes, then passed the stretched neck on to their children. This mechanism for evolutionary change did not turn out to be correct, and today, we often remember Lamarck as the one who "got the wrong answer.
He was one of the very first to seriously engage with the idea of evolution and to actually suggest how it might take place. This contrasted with the predominant view that the geology of the planet was a consequence of catastrophic events occurring during a relatively brief past.
Thomas Malthus was another thinker who strongly influenced Darwin.
His ideas were crucial in Darwin's realization that most natural populations produced more offspring than their environments could support, such that only a fraction of the offspring could survive and reproduce. Darwin and the voyage of the Beagle Darwin's seminal book, On the Origin of Species, set forth his ideas about evolution and natural selection.
These ideas were largely based on direct observations from Darwin's travels around the globe. From tohe was part of a survey expedition carried out by the ship HMS Beagle, which included stops in South America, Australia, and the southern tip of Africa.
At each of the expedition's stops, Darwin had the opportunity to study and catalog the local plants and animals. Over the course of his travels, Darwin began to see intriguing patterns in the distribution and features of organisms.
Moreover, he noted that each finch species was well-suited for its environment and role. For instance, species that ate large seeds tended to have large, tough beaks, while those that ate insects had thin, sharp beaks.
Darwin didn't figure all of this out on his trip. Gradually, however, he came up with an idea that could explain the pattern of related but different finches. On each island, the finches might have gradually adapted to local conditions over many generations and long periods of time.
This process could have led to the formation of one or more distinct species on each island. If this idea was correct, though, why was it correct?
What mechanism could explain how each finch population had acquired adaptations, or features that made it well-suited to its immediate environment?
During his voyage, and in the years after, Darwin developed and refined a set of ideas that could explain the patterns he had observed during his voyage. In his book, On the Origin of Species, Darwin outlined his two key ideas:Darwin's theory shows that evolution is the process of natural selection acting on random variation.
I know your blood is already boiling from reading the headline above and that your intellectual self-defense mechanisms have been activated to refute all ideas you are about to encounter henceforth, but make yourself a cup of tea, relax, and consider the following viewpoint that has been concealed from you during your entire life.
An Introduction to Biological Aging Theory Second Edition Theodore C. Goldsmith Azinet Press. Huxley was the first to construct, on the basis of Darwin's theory of evolution by natural selection, a clear and logical image of biological man, and as such, is clearly the founder of evolutionary anthropology.
An anti-Darwinian theory of biological origins that was well received and widely accepted for years was creative evolution. This theory attempted to deal with some of the major problems of Darwin's theory, especially the origin of biological information. Darwin's Theory of Evolution - Natural Selection While Darwin's Theory of Evolution is a relatively young archetype, the evolutionary worldview itself is as old as antiquity.
Ancient Greek philosophers such as Anaximander postulated the development of life from non-life and the evolutionary descent of .