What was Darwin's explanation for the evolutin of species?

Answer 1

the species that can adapt to the environment will survive, then they will pass their genes to their descendants and so on, that's the easiest explanation i came up with

Answer 2

Normally a few individuals of a species will mutate slightly. Darwin didn't know why but the reason is random errors in the replication of DNA.

If these variations are more likely to lead to those individuals either reproducing or surviving, then those traits will tend to be inherited more than others. This is what is called 'survival of the fittest.'

The 'aha' moment for Darwin was his visit to the Galapagos Islands, where he found variations in bird species.

The best modern example of this is the evolution of bacteria in response to better anti-bacterial medications. Every few years, bacteria resistant to the latest and greatest antibacterial emerge. This is because all of the germs which could not stand up to that particular drug have been killed off and some of them mutate into resistant strains.

Answer 3

The process that we know as evolution can come about through several mechanisms. The most well-known, and commonly described mechanism, is that of natural selection.

1) Errors in DNA replication lead to mutations.

2) Mutations can be positive, negative, or neutral: Most people are familiar with the concept of positive or negative mutations, the former being somehow beneficial to the organism, the latter leading either the organism's death or decreased fertility/fecundity.

What many people forget is that many mutations are neutral. They don't lend any immedate benefits or drawbacks to the organism, or at least not enough to noticibly increase or decrease their fitness. These mutations will generally be maintained in the population at a small but stable ratio, leading to some genetic diversity within a population.

3) Natural selection steps in: Let's say a change in the environment affects a certain portion of a species. For example, the weather over time gets colder in the northern part of a species' range. This is a grossly oversimplified example, but ride with me.

Let's say that within this species, 0.1% possessed a previously neutral mutation which made the follicles of their fur an average of a couple millimeters longer. The climate change now turns their neutral mutation into a positive one, because they can keep warmer than their thinner-haired neighbors. Let's say the thick-furs now produce an average of 5.4 offspring in their lives, whereas the thin-furs produce only 5.3.

As you can see, if the climate remains cold, over many, many, many generations, the organisms possessing the thick-fur gene will start to outnumber those those with the thin-fur gene. Any further mutations leading to even thicker fur will be positive, and will similarly spread through the population. Eventually, organisms with fur of the original length (when the climate change occurred) will be rare--not necessarily because they are unable to deal with the cold, but simply because they were outnumbered by those that could deal "better".

4) Formation of a new species: The definition of "species" has become very fluid over the past few years, especially with advances in genetics. However, the most commonly stated definition has to do with reproduction: members of two different species either cannot produce offspring, or produce sterile offspring.

It's important to note that this does not happen overnight. An animal does not suddenly give birth to a new "species" which is then incapable of breeding with the rest of the population. Changes between generations are generally very small, and great differences are only seen over long periods of time. The real key would be to see if the population existing now would be able to breed with the population that existed ten thousand years ago. If not, then we would say the population has evolved into a new species.

To take the example of the furred animals above: along with being selected for fur diameter, other changes have been occuring as well. Perhaps the changes are in response to the different energy requirements for fur of a thicker diameter, perhaps they are in reponse to the environmental change itself.

Let's say a scientist recognizes that the thick-furred animals have many similarities to the thin-furred variety to the south (which, having undergone little selective pressure in the past few thousand years, represents something similar to the original ancestor that led to the thick-furred variety). She attempts to interbreed them, but no luck--although they mate, and the females may even conceive, they can't bring any offspring through a full gestation. The scientist concludes that the two varieties have evolved into different species.

Answer 4

There are two essential elements:
- Variation. No species breeds absolutely true -- there are frequent genetic variations from generation to generation. A lot of these are inconsequential, a few are detrimental (and may be lethal), but some confer an advantage.
- Selection, either natural or artificial. An advantageous variation will reproduce more rapidly than the original wild type, and if the variation is sufficiently advantageous, may take over entirely. Nature has been doing selection for some four billion years. Humankind has been doing it since the rise of agriculture.

Given these two elements (and it is evident that they both exist), evolution is inevitable. You can see from this that evolution is proved correct.

Answer 5

Darwin basically said that new species come about through nonrandom cumulative selection. Nonrandom because if it was random then evolution would not occur. Cumulative because the selection builds on itself.

Darwin's 4 postulates:
1. Variation is present within populations
2. Variation must be heritable.
3. Each generation has more offspring then can survive.
4. Survival and reproduction are not random: The individuals that survive and go on to reproduce, or who reproduce the most, are those with the most favorable variations. They are naturally selected.

Answer 6

Well Darwin was one of the earliest people to try and study the "speicies" question. And I don't really know the date but at some time he got his big break, at a group of islands called the galapacos islands. After returning to England he studied his researches against and sometimes with his rival Malthus. And he finally came up with the statement about competetion for food sources which led him to believe that species change their body shapes just to get some means of getting what they want...food. Then he came up with the statment that is still a motivating and real statement
survival of the fittest. HIs book was " Origin of species."

Answer 7

Really, I can not tell you everything in a few words. But this is the basic explanation. Stuff happens to genes randomly. That's unpreventable. In the event that the 'stuff' that happened gave a creature an advantage in any way (e.g. a bird with larger beak more easily eats berrys), that creature will live a generally healthier life than the rest of them, and they will produce offspring that inherit its genes and also obtain that 'advantage'. The ones that do not have that advantage will eventually die out, but this is a very very slow process.

Answer 8

That people who can't spell wont get help with their homework. His theory of evolution is broken into many different parts. I assume you were supposed to read the whole publication, and I think you still need to. Try Huxley as a companion read if this is for your own gratification - Man's Place in Nature. Also there's a book called The Beak of the Finch. Inherit the Wind. Lots of things to help you understand.

Answer 9

many people have given you examples of evolution within a species but the trick is the how to explain a new one. one example is the Indian and African elephants. they are different species (meaning that they cannot interbreed) but it is thought that at one time they were the same. then the Indian and African continents separated and the two went off on different evolutionary paths, changing gradually over the generations until they changed so much that they could no longer interbreed.
from that point onward they are different species and are on completely different tracks.

Answer 10

Before he died, he denounced his theory of evolution and admitted that he was wrong. They don't teach that little fact. It would be far easier to be an atheist if one believed in evolution and let it go at that. Evolution is ludicrous.