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I have yet to make up my mind regarding the theory of evolution. Whilst doing some reading on dnafish I read that DNA itself provides evidence for the theory of evolution:
Yeast, trees, flowers, corn, mice, frogs and humans share the same DNA. We know this is true the DNA code has been decoded and the closer evolutionary relative, the more the DNA matches.
But does the theory of evolution say that trees evolved from the same organisms as mammals, reptiles, etc?
When Darwin developed the theory of evolution by natural selection, he was at that time not able to identify the underlying mechanism responsible for the hereditary of traits. Of course, the hereditary of traits is something we can directly observe, and exploiting such a mechanism is exactly what a person breeding dogs, horses or roses does.
The discovery of genes and DNA revealed the underlying mechanism. This is an important point, because for scientists to be really satisfied you need both a verified observation and a plausible mechanism.
Since evolution occurs through the gradual change of traits, which is reflected by gradual changes in the genes, the theory of evolution makes a prediction: The closer two species are related in their evolutionary history, the more similarities in the genetic code we should expect. Molecular phylogenetics (i.e. inferring relatedness from DNA sequences) produces results that are consistent with other methods of inferring relatedness among species: morphology, geography, and the fossil record. Therefore, it adds credibility to the only theory that predicts these patterns, evolution from a common ancestor. It extends the theory of evolution by allowing inferences to be drawn even in the absence of geographic and fossil-based evidence.
While in science, one does not deal in absolute truths and proofs, but merely with hypotheses and validations or falsifications thereof, this discovery lends credibility to the theory of evolution.
Life only had to happen once, and from that single point of origin, all else diversified.
So yes, plants and animals indeed are hypothesized to share a common ancestor and DNA sequencing is continuing to generate more and more proof:
'29+ Evidences for Macroevolution'
Absolutely! ALL organisms are evolved from the same original organism (that is what common descent means). I just finished reading Greatest Show on Earth, which addresses most points one by one. Remember, in a field as complex as biology, there will never be a singular item one can point to and say, "See, because of X, it's all true." I also recommend Why Evolution is True as reading material. Talk Origins also has an extensive discussion on The Molecular Sequence Evidence (i.e. genes, RNA, etc.). It even speaks of falsifiability in the article (a hallmark of real science).
Further points to consider regarding evolution.
There are many reasons why one should accept evolution. The idea of reserving judgment on it seems rather foolish considering the non-scientific origin of the debate. I suggest a reading of this simple list or this more expanded list of the logical mistakes made when attempting to refute evolution.
In order to keep this answer of reasonable length, I am not going to blockquote or put pictures in. It would just get too long and unmanageable. I feel that the Talk Origins essay is the best available on online for free. Otherwise, read the books recommended earlier.
I'll try to answer this by using an analogy:
English and German seem like two very different languages. Yet if you look a little closer you'll find similarities:
- Mother - Mutter
- House - Haus
- Boat - Boot
- Earth - Erde
- Weather - Wetter
- Summer - Sommer
- ...
is this just pure coincidence?
The more similarities you find, the more likely it would seem that these two languages have a common ancestry.
"Universality of DNA" means that the blueprints of all life forms on earth is written in the same language.
An example is Synthetic Insulin for diabetics: basically, the specific gene for human insulin is embedded into a bacteria's genome, and because the code is written in the same language, the bacteria 'builds' human insulin, which we can later harvest.
Another simple example is the common cold: the virus infects our cells, injects its DNA (or RNA), and our own cells end up replicating the virus because it's blueprint is written in the same language.
Like with English and German one might wonder "Is it just pure coincidence that humans, animals and plants have developed the same language?"
Or does this hint, that all life on this earth is somehow connected? Maybe through common ancestry?
EDIT: just saw that 'shellholic' posted a similar answer.
Before to compare DNA between organisms, you have to admit it is written in the same "language" between species (which is the case). But, by admitting that, you already admitted evolution. This is due to the "universality" of DNA translation.
In shortcut, the DNA translation is the process that read DNA and output proteins (the building blocks). It is quite arbitrary that AUG (a piece of DNA code) is translated to a methionine. But every known living on the Earth use the same "language" with very little changes (think English vs American, not English vs German).
Once you proved to yourself that evolution form a common ancestor is the most simple hypothesis to justify that the same code is used everywhere (plants and animals, unicellular and very complex organism,...) you can now try to calculate when they separated from a common ancestor. And if you make this distance calculation, you obtain numbers that are not random, that is a proof of a not random hypothesis. Better, those number are the same as the geological and radiometric dating.
Definitely, there is a lot of strong genetic evidence for evolution! The amount of genetic evidence we've been able to collect over even the past few years has increased in an astronomical rate, and we keep on receiving more and more data confirming evolution. Perhaps one of my favourite pieces of evidence is the fusing of chromosome 2 in humans. I'm just gonna quote the wikipedia section here, it gives a good general over-view:
Evidence for the evolution of Homo sapiens from a common ancestor with chimpanzees is found in the number of chromosomes in humans as compared to all other members of Hominidae. All hominidae have 24 pairs of chromosomes, except humans, who have only 23 pairs. Human chromosome 2 is a result of an end-to-end fusion of two ancestral chromosomes.[17][18]
The evidence for this includes:
The correspondence of chromosome 2 to two ape chromosomes. The closest human relative, the common chimpanzee, has near-identical DNA sequences to human chromosome 2, but they are found in two separate chromosomes. The same is true of the more distant gorilla and orangutan.[19][20] The presence of a vestigial centromere. Normally a chromosome has just one centromere, but in chromosome 2 there are remnants of a second centromere.[21] The presence of vestigial telomeres. These are normally found only at the ends of a chromosome, but in chromosome 2 there are additional telomere sequences in the middle.[22]
Chromosome 2 thus presents very strong evidence in favour of the common descent of humans and other apes. According to J. W. IJdo, "We conclude that the locus cloned in cosmids c8.1 and c29B is the relic of an ancient telomere-telomere fusion and marks the point at which two ancestral ape chromosomes fused to give rise to human chromosome 2."
http://en.wikipedia.org/wiki/Evidence_of_common_descent#DNA_sequencing
(The rest of that article is well worth reading too, if you have the time. Well obviously not an in depth technical work in the classic sense, wikipedia is excellent for getting a broad-scope overview of a topic, and often provides many useful, credible references at the bottom for further research)
