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Evolution

The scientific theory according to which populations change gradually through a process of natural selection.

5,264 Questions

How is Darwin's theory called a theory?

His first paper was titled:-

'On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection'

His book was titled

'On the Origin of Species by Means of Natural Selection, or The Preservation of Favoured Races in the Struggle for Life' (usually abbreviated to On the Origin of Species).

In these publications he set described things/features that could be seen in the biological world and presented a process by which these could arise over time, with evidence to support these proposals. As such his publications conform to the scientific method and may be called a theory.

His proposals are now well accepted as being a correct/true description about how the variety of life as we know it came to be on our planet and form the basis of modern evolutionary theory. *In scientific terminology, a theory is a proposal/explanation with evidence that could be defended (a fossil record, the different bird specie variations, etc.) and an idea that can be used to predict further developments; in this case, that there have been/are/will be major changes to an organism's DNA/RNA over time as it adapts to its environment, which can be proven with a decent microscope and some bacteria, and common acceptance in the scientific community (tick this box).

Why is time an important factor in the process evolution by natural selection?

Because natural selection only preserves incremental beneficial traits to the organism and many different areas of the organism are undergoing mutation and natural selection at the same time against the backdrop of the immediate environment. If a population of organisms, subject to allele change due to natural selection, is not in a changing environment, or split in a allopatric event, then adaptive change will be very slow, or will not happen at all and selection will winnow those variants and stabilizing selection is taking place. Regression to the mean of phenotype.

What are three areas of Lamarck's hypothesis of evolution?

Main points of Lamarck's theory are the following . 1 Changing environment produced need for new organs . 2 there is an increase in size of organs and organisms . 3 use and dis use of organisms . Inheritance of acquired characters .

What is David Suzuki's greatest accomplishment?

David Suzuki is well known for saving energy, and trying to help our environment. He writes speeches, and stories for both adult and children. He is a wonderful man who is trying to save our world.

What is evolution and how could evolution affect vestigial structures?

Vestigial structures are structures that no longer fulfill their original purpose. Take wisdom teeth in humans as an example of this. At one time, as we know from the fossil record, human jaws were larger and could accommodate those wisdom teeth. As jaws became smaller wisdom teeth erupted into too small a mouth more and more times over human evolution until very few mouths can accommodate the onset of these teeth and they now are generally pulled at eruption. So, we can see the history of human evolution in our teeth!

Are carrots related to humans?

Not closely. However, depending on how far down the evolutionary ladder you go, you will find a common ancestor. It may be just a clump of moss but it's there.

Can all mutations cause evolution?

Mutations often occur without evolution. Every human child, for example, has dozens of new mutations that he/she did not inherit from his/her parents. Evolution is dependent on a statistically significant change in allele frequencies. In layman's terms, the species - in general - has to change for evolution to have occurred.

Here is an example: Right now, how many legs do dogs have? They have 4 legs. Is this true or ALL dogs? No, but in general dogs have 4 legs. Most dogs have 4 legs. If a puppy were born with 5 legs, it would be a "weird" dog. Just because it has a new mutation does not mean dogs have evolved.

However, if you were to go to the future 100 years from now and find out that dogs now have 5 legs. It is now 'normal' for dogs to have 5 legs. A dog born with only 4 legs is a 'weird' dog. - Then evolution has occurred. The species (dogs) has changed (in general).

*The change has to be "statistically significant" within the species to count. If dogs change from 1% having 5 legs to 2% having 5 legs, it's probably not significant. If it changes from 1% to 90% that is very significant. Those examples are obvious, but where do you draw the line? You will learn how to find out significance in statistics class.

A mutation could potentially lead to evolution, but every mutation is not guaranteed to cause evolution. In fact, most mutations do NOT lead to evolution. It entirely depends on the gene, the mutation, the species, and things like: the environment (natural selection), human choice (artificial selection), or chance (genetic drift). Most mutations are either unnoticed (occur in dormant genes, or they do not make a difference in protein structure or function), or they are harmful. It's a lot easier to mess something up than to improve it.

*Keep in mind however, all evolution is not better. That is not part of the definition. Evolution is just change in the species over time. Natural selection is usually evolution that's improvement. People often assume that natural selection and evolution are the same, but they are not. Evolution can be harmful or just neutral. For example, if I keep breeding dogs that are blind, I can evolve dogs to include blindness as a normal trait. However, that would be detrimental to the life of dogs now.

What evidence did Stephen Jay Gould use to support his theory?

The discontinuities in the fossil record that seemed to show that some species or taxons were in a state of non-evolution and then seemed to go through a burst of rapid evolutionary change. This is really only seen in the fossil record and does not have a lot of support in disciplines such as molecular genetic, which genetic divergence back through time in today's genomes.

What are the 12 main periods in the four main eras of earths past?

Cenozoic * Recent (Holocene) * Pleistocene * Pliocene * Miocene * Oligocene * Eocene * Paleocene Mesozoic Mesozoic * Cretaceous * Jurassic * Triassic Paleozoic * Permian * Carboniferous (Pennsylvanian Mississippian) * Devonian * Silurian * Ordovician * Cambrian Pre-Cambrian You can remember this using the following mnemonic (starting at the bottom)

Camels ordinarily sit down carefully perhaps their joints creek probably early oiling will prevent permanent rheumatism. For a more detailed view of this look in the related link below.

What individulas most likely to survive and reproduce are those that?

Are most adapted to their environment. This may also be described as filling a "niche," meaning they are the best at a particular way of surviving, such as cheetahs being incredibly fast, insects being poisonous, or humans being very intelligent.

Why do you walk on two legs?

Technically humans do have four legs, however, when we evolved the muscles in our legs grew stronger and longer allowing us to be able to stand upright. Due to the body capacity of cattle and how they are designed they are not able to stand upright.

How is evolution a theory?

It is a theory because it is a comprehensive, well-supported model explaining a well-defined set of independently verifiable observations in an independently verifiable and falsifiable manner.

What is non-adaptive evolution?

According to the way most people think about evolution, species evolve because they are becoming more adapted to their environments (natural selection). This is adaptive evolution. Evolution, however, can also happen for reasons other than natural selection. For instance, sexual selection often has little to do with adaptation to the environment (in many species, the colors or loud calls of males attract females for mating but also attract predators; a sexual advantage often does not correspond to an environmental advantage). Sexual selection impacts evolution but has nothing to do with adapting to the environment.

The classic example of nonadaptive evolution is genetic drift, in which sheer chance leads to changes in the frequencies of alleles. Evolution occurs because the frequencies are changing, but the alleles are not changing for any reasons of adaptation; it is just random luck.

What is the role of isolation in evolution?

To develop new species by making the isolated groups change with their environment, separated from others of their species. Eventually the isolated group will change so much they wont be able to reproduce with the others, making a new species.

How does selective breeding differ from evolution?

Selective breeding happens within closely related species. useful Techniques

GM Food produces a wide range of characteristics that aren't possible with selective breeding. It can alter an organism's DNA with much greater precision-genes can also be transfered or manipulated

How does analogous structure support evolution?

Analogous structure supports evolution because some of these structure may have existed long ago, however not all analogous structure support the same evolutionary path.

Which is the following would describe lamarcks ideas about evolution?

Mainly that animals can change their own forms over time and that these traits are inherited by their offspring. A classic example is of a giraffe making its neck longer and longer by stretching for food that is high in the trees. These individuals would then produce children with long necks.

This concept of evolution is incorrect because individuals do not have conscious control over physiological changes to their body structure, and these conscious changes would definitely not be inheritable by offspring. Change is caused by random mutation in genes. Changes in body structure only happen at the group level because individuals born with an advantageous trait will produce more children than those who don't.

However, it should be noted that the newly emerging field of Epigenetics shows that Lamarck was at least partly right. The environment in which an individual lives can determine when or if a gene is activated. This can be passed on to offspring.

How do embryos provide evidence of evolution?

It was previously thought that the early stages of the human embryo were similar to those found in other types of creatures (Haeckel's diagrams), but it has now been shown that this is not quite conclusive (google "Haeckel diagram fraud"). There is still a lot of research going on in this area, and the data is constantly changing.

When did oxygen levels start to rise on Earth?

After the earth was created, there was just one gigantic ocean. At some point, single-celled organisms formed - the first plants. They made their own energy using the sun and carbon doixide (photosynthesis) and one of the waste products was oxygen. As they multiplied, more and more oxygen was produced, forming the start of today's atmosphere.

Can you name some extreme environments?

there are ...

deserts

polar regions

They are made by earth ...

things like earthquakes and wars and stuff are caused by man

I hope this helped

Why do people disagree on the origins of man?

Because some religions say one thing while scientific evidence says another. Neither group can accept the other's point of view, since they are simply incompatible.

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I think it is because they see Creationism and Evolutionism as mutually exclusive rather than supportive of each other. Many people who believe in evolution are atheists, but despite the rumors about him, Charles Darwin was not. Many people who believe in special creation talk of God creating man in his own image, but they are so preoccupied with the physical image that they forget about the spiritual image. They represent two extremes to which a person is expected to choose one or the other.

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I would have to say that throughout human history there has never been a single unanimous agreement, at least not in areas where speculation has room to maneuver.

This question could almost be phrased "why doesn't everyone believe in Jesus?" Or perhaps, "why isn't everyone as objective as science?"

I personally think people find some status in disagreeing, especially if the disagreement is well thought out and eloquent (or backed by aggression). Agreeing with someone about something you did not know prior gives them the status of having contributed to you, while passing such to another lends the same. There is power in agreement, some are more loath to give it up than others.

This is a very lame answer, but I believe the question to be without any single right answer.

Can geographic barriers guarantee the formation of new species?

Guarantee? No. If there is not sufficient variance genetically by recombination and mutation in the immediate environment then nothing will speciate. But geographic barriers are very likely to aid speciation.

Why is it reasonable to assume that the earliest life on earth was anaerobic?

FeO

Oxides of iron only came on the scene well after there were trace fossils of organisms that we can reasonable assume did not use oxygen fueled metabolisms.

Why do phylogenic trees provide strong evidence of evolution?

They are not, in themselves. Natural selection is inferred from realtime observations of natural and experimental populations, as well as geographical distribution of traits. However, using this knowledge derived from observing realtime selection, we can formulate and test hypotheses about past selection against modern genomes.