How do you know that evolution has been going on for millions of years?

Answer 1

The question of 'how do you know evolution does not exist?' does not have a rational answer. Evolution can be proven through science today. Any religion denying evolution is based on what people believe, rather than what science says. Look at fossil records. Those records which are more than a billion years old show evolution. Even our DNA. Humans' DNA is 96% the same as chimpanzees. If we didn't evolve from a common ancestor, why are we almost exactly the same?

Evolution explains why we are here today and how we got here, based on the facts.

Answer 2

Because its possible to trace the changes in species in the fossil record. Fossils can't usually be dated directly, but it is possible to date igneous rocks directly using radioactive dating: Some elements are radioactive and gradually convert from one isotope to another. For example, uranium 238 (238U) will gradually convert to lead (206Pb). It will do this at a constant rate. The rate is described as a half-life of the isotope in question. This is the period of time it takes for half the atoms of 238U to convert to lead. For this particular element, the half-life is 4.47 billion years and uranium/lead dating is useful for rocks between 1 million and 4.5 billion years (as luck would have it!). As igneous rocks affect sedimentary rocks, which contain fossils, it's possible to deduce the age of the various geological ages. Before the development of radioactive dating, geologists strongly suspected that rock formation was measured in millions of years; by thinking about how long it would take to lay down layers of sedimentary rock. An Irish priest and geologist (Samuel Haughton) calculated that sedimentary rocks were laid down at the rate of around 8000 years per foot. This gave the age of the Earth, using this technique, of around 2000 million years. Apart from the fossil evidence, genetic evidence can also be used to estimate when species split from common ancestors - these calculations agree well with the fossil dating.

Answer 3

Charles Darwin was by no means the first to say that evolution was the basis of the species we see today, but he did develop the Theory of Evolution by Natural Selection. And he addressed the very question, How do we know that evolution occurred, rather than a special act of creation?

Statistical distribution of speciesDarwin realised that where many species of a genus have been formed through variation, circumstances have been favourable for variation. Hence we may expect that circumstances would generally be still favourable to variation. On the other hand, if we look at each species as a special act of creation, there is no apparent reason why more varieties should occur in a group having many species, than in one having few.

To test this hypothesis, Darwin arranged the plants of twelve countries, and the coleopterous insects of two districts, into two nearly equal masses, with the species of the larger genera on one side, and those of the smaller genera on the other side. Invariably a larger proportion of the species on the side of the larger genera presented varieties. Moreover, the species of the large genera which presented any varieties, invariably presented a larger average number of varieties than the species of the small genera.

What he was able to show was that, where many species of a genus have been formed, then on an average, many are still forming. This belies a special act of creation at a single point in the past.

Proliferation and eventual extinction of speciesSince some creationists claim that the extinction of fossil species in the geological column can be blamed on Noah's Flood, it is also necessary to look at whether the scientific evidence favours the theory of evolution.

Scientists have found that, generally, if the number of species in a genus (group of closely related species), or the number of genera in a family, be represented by a vertical line of varying thickness, crossing the successive geological formations in which the species are found, the line will begin either as a sharp point or narrow line, then gradually thicken upwards, sometimes keeping for a space of equal thickness, then thin out in the upper beds, marking the decrease and final extinction of the group. This is consistent with evolution, but hard to explain by the creationists' argument of Noah's Flood.

Answer 4

Evolution (the change of a species over time) is an observable phenomenon that occurs in all cellular organisms. It has been observed in the fossil record, on the microscopic level (people who receive flu vaccinations every year know this), and in laboratories. Biologists have long realized now that it is a fact of life.

Modern biologists have been attempting to explain the mechanics of evolution. Over the past 150 years, biologists have found strong evidence that the following three mechanisms are responsible for evolution:

Natural Selection: We know that random mutations of genes occur, and that these genes can potentially help or hurt the organism. If the mutation hurts the organism, then the organism has a smaller chance of living long enough to pass on its genes. If the mutation helps the organism, then the organism has a greater chance of living long enough to pass on its genes. It can be easily described as "survival of the fittest," but on the genetic level.

Genetic Drift: Genes, which code for traits, come in several different forms called "alleles." Some alleles have dominance over another, and will be expressed even in the presence of other non-dominant (recessive) alleles. Throughout generations, some alleles can be removed from a species (see http://en.wikipedia.org/wiki/Genetic_drift for a complex explanation). This can be either beneficial or harmful to the species, depending on if the allele had a positive or negative effect for the organism. An example of a positive effect would be if a disease caused by a recessive allele was slowly removed from a species by constantly being paired with a dominant.

Genetic Flow: Gene flow is the spread of different alleles between certain populations of the same species. This can increase genetic variation, and also contributes to genetic drift.

In summary, we have observed evolution in nature, and we have a very well-supported explanation for how evolution works. That is how we know that evolution happens.

Answer 5

With all the evidence that has been accumulated about evolution, anyone who could prove the Theory of Evolution entirely wrong and that evolution has not occurred, would justifiably be famous.

Since before the time of Charles Darwin, geologists, paleontologists and scientists from myriad other disciplines have studied the evidence of the rocks. They have ascertained the age of the earth at 4.54 billion years, plus or minus 45 million, and have studied and classified thousands of extinct species. There is ample evidence of the transition from one species to another - evolution.

Answer 6

Scientists use a combination of evidence from the fossil record, genetic analysis, and comparative anatomy to track changes in species over millions of years. By examining these different sources of data, researchers can piece together the story of how species have evolved and changed over time.

Answer 7

I learned about it in school and from books and from the internet.