Evolution

Some people may not believe Charles Darwin's theory of evolution due to personal or religious beliefs that conflict with the idea of natural selection and common ancestry. Some individuals may also have misconceptions or misunderstandings about the scientific evidence supporting evolution.

Human evolution began millions of years ago with our common ancestors, who lived in Africa. Over time, different species of hominins emerged and evolved, eventually leading to the development of modern humans, Homo sapiens. Key events in human evolution include bipedalism, tool use, increased brain size, and social behavior.

Evolution is not concerned with the creation of the earth. It explains how modern species developed from more primitive species of the past.

Cosmology explains how the earth was formed. At some stage, a supernova star exploded in the neighbourhood of our sun - within a few million light years from here. Supernovas are formed as giant stars die and are not entirely uncommon. And giant stars, because of their far greater mass, are able to convert their hydrogen into heavy elements before finally dying. Conversion of hydrogen into heavy elements is also well known to nuclear physicists. So, our supernova exploded and sent an enormous amount of heavy elements out into empty space. A very small part of this was captured in orbit around our sun, where it eventually concentrated into the various planets and other bodies that orbit the sun. One of these was, of course, the earth.

This pattern fits the model of punctuated equilibrium in evolution. It suggests that species experience periods of little to no change followed by rapid bursts of evolutionary change that result in new species formation. This is in contrast to gradualism, which posits a slow and constant rate of evolution over time.

Genetic drift is the spread of specific random variations throughout the gene pool in the absence of specific selection pressures. There's always random variation in the population, but there aren't always changes in the environment for the population to adapt to. So natural selection, in stead of moving the population towards adaptation, might select from that random variation to move 'sideways', as it were, to a state that's equally well-adapted to the environment as what came before, but different. As random variation may produce many variants that are, more or less, equally well-adapted to their environment, the direction of evolution that results is more or less random.

The smallest biological unit that can evolve over time is an individual organism, typically a unicellular organism like bacteria or archaea. These organisms can undergo genetic mutations and natural selection, leading to the evolution of their populations over generations.

Examples of evolutionary adaptation include the development of camouflage to avoid predators, the evolution of a protective exoskeleton in insects, the elongation of giraffe necks to reach high leaves, and the development of antibiotic resistance in bacteria.

No theory has proof "above" any other; either it has enough supporting evidence to be valid or it doesn't. They are all suported by individual evidence (sometimes actually sharing it), and each theory also supports the overarching theory of evolution.

However, the proof for undirected mutation is simply the existence of mutations. They have no 'direction' - taken to mean either a direct cause or a purpose - so the fact they are there is enough proof. Incremental change is supported by the fact we can see it in both simple studies from a lab and real world situations; for example, the required amount of certain known and widespread antibiotics to kill a given sample of microbes has increased by large amount since their discovery in the 20th century. Fossil records contain a large number of species who changed over time and the changes can be quite clearly seen when compared.

Punctuated equilibrium is not ' a theory of evolution ' but well ensconced within modern evolutionary theory. Scientists look for evidence, not proof. The evidence suggests that punctuated equilibrium and incremental change are not mutually exclusive and both can occur in nature.

The two main factors are mutation and natural selection.

Mutations are random changes in our DNA that cause changes. Some of these changes are bad, some are neutral, and some are good.

This is where natural selection comes in. If the mutation is bad, then that organism is less likely to mate and pass down the gene. The organism dies along with the mutation that made it less fit. If it is neutral, which is what most mutations are, then nothing happens. If it is good, then the organism is more likely to survive and pass down the gene which will then propagate through the species.

Charles Darwin is credited with developing the theory of evolution through natural selection in his book "On the Origin of Species," published in 1859. Darwin’s work revolutionized the field of biology by proposing that species evolve over time in response to environmental pressures.

We have conducted studies of the deoxyribonucleic acid (DNA) of mitochondria (mtDNA), organelles within cells that have their own unique DNA. This DNA is usually inherited only from the mother, and so changes in it serve as a useful clock for timing speciation events. We have, for example, replaced the mitochondrial DNA of cow egg cells with those from rabbits, fertilized these eggs and allowed them to gestate. The calves are born with the mtDNA of lagomorphs, and they live just fine, which shows there is nothing intrinsic to rabbit mtDNA that will not work in cows.

We can construct a hierarchy of life very similar to the tree designed by Linnaeus using mitochondrial DNA. This tree demonstrates the interconnectedness--the shared ancestry of life. This is probably the key genetic evidence for evolution.

There are plenty of other good pieces of evidences. Endogenous retroviruses (ERVs) are snippets of DNA inserted into genes or introns which then may be passed from one generation to the next. There is no compelling reason for the same sequences of foreign DNA in similar organisms aside from that of common ancestry.

As for human beings, we have our own tell-tale genetic evidence. Our #2 chromosome is clearly the result of a fusion of two earlier primate chromosomes. The evidence for this is abundantly clear. In addition, we also have a non functioning gene, L-gulonolactone oxidase (GULO) for the syntehsis of ascorbic acid we share with our simian ancestors. Why should monkeys and men share this common defect aside from common ancestry?

The theory says that living things have changed over time and are not static. Charles Darwin proposed a way it could have happened, namely by natural selection. For example, the finch with the larger bill is better fit in an environment with mostly nuts than the finch with the smaller bill. It was later found through technology that living things mutate so over time, the thing with slightly better mutations survives. All this detail is more specific than the theory of evolution, which just says that living things change (so evolution simply predicts change). Sorry it took to long to answer.

Changes in the gene pool are part of the evolutionary process, which encompasses both adaptation to the environment as well as other mechanisms of change such as genetic drift and gene flow. Adaptation specifically refers to the process by which organisms become better suited to their environment through natural selection acting on heritable traits.

Improves the likelihood of survival.

Mating does this because it allows for much quicker evolution due to the new combinations of DNA that results from two parents rather than the asexual reproduction of a single organsism which basically results in a clone of itself.

Opponents may argue that there is not enough evidence to support evolution, that the fossil record is incomplete, or that the complexity of living organisms cannot be explained by natural selection alone. They may also question the idea that life arose from non-living matter through natural processes.

Charles Darwin is credited with developing the theory of evolution through natural selection. Published in his work "On the Origin of Species" in 1859, Darwin proposed that species evolve over time through a process of natural selection, where individuals with advantageous traits are more likely to survive and reproduce.

The evolution of oxygenic photosynthesis by early cyanobacteria around 2.4 billion years ago significantly altered Earth's atmosphere by increasing oxygen levels. This sudden rise in oxygen caused a mass extinction event as many anaerobic organisms were unable to survive in the new oxygen-rich environment. Life forms that adapted to aerobic metabolism thrived, leading to the diversification of more complex organisms.

Algae reproduce sexually through a process known as isogamy, in which similar-sized gametes fuse to form a zygote. The evolution of sexual reproduction in algae is believed to have occurred around 1.2 billion years ago and provided survival advantages through genetic diversity. As algae evolved, they developed more complex reproductive strategies, such as anisogamy and oogamy, which involve the production of gametes of different sizes. These different reproductive strategies have contributed to the diversity and success of algae in various environments.

Actually, the process of a gene changing within a lifespan is not called evolution. Evolution refers to changes in the genetic makeup of a population over many generations. Changes in a gene within an individual's lifespan may be due to mutations or environmental factors, but this does not necessarily lead to evolution.

With the nested hierarchy of phylogenetic trees in front of you, showing in general relief the biochemical, physiological, behavioral relatedness extended from the forked nodes, and going along through time one sees evolution in action. Change over time.

The mechanisms of evolution are called natural selection, genetic drift, gene flow, and mutation. These mechanisms work together to drive changes in populations over time, leading to the diversity of life we see today.

Chemical evolution: the evolution of the elements (building blocks of matter)

biological evolution: the small scale change in a population that can be passed from generation to generation

Both of these are changes that occur to gradually create a new species or substance

The theory that proposes evolution occurs steadily in tiny changes over long periods of time is gradualism. This idea suggests that species evolve slowly and continuously through small, incremental changes rather than through sudden, dramatic shifts.

Darwin proposed that natural selection takes place as individuals best suited to their environment survive and reproduce, passing on their advantageous traits to offspring. This leads to the gradual progression of characteristics that are favorable for survival in a given environment.