What is DNA?
The term DNA refers to deoxyribonucleic acid. It is a blueprint which specifies exactly how the person is formed, every single detail of them! Every aspect of the human body is dictated by the DNA within each cell. The amount of information in a pinhead of DNA is the equivalent of a pile of paperback books 500 times higher than the distance from the earth to the moon. And the information in each book is unique!
DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Each human cell contains about 3 billion bases of DNA. This is a huge amount of information. It is inconceivable that it could occur by random chance.
There are control mechanisms built into DNA which can replicate itself as it does when cells divide and each cell contains an exact copy of the DNA in the old cell.
Another control mechanism operates to identify damaged DNA and to repair the damage. So changes in the DNA are seen as faults and the cell attempts to repair itself. Therefore the idea that new genetic material can appear in the DNA to create a new species is contrary to the mechanisms supposedly created by the evolutionary process!
Can new DNA be created?
Damaged DNA could be passed on to the next generation. In most cases this is detrimental, even harmful. We see all sorts of consequences in people because of incorrect DNA programming resulting in some aspect of their body being formed wrongly. But this is alway a negative consequence often resulting in ruined lives and early deaths.
What we simply do not see are 'improvements' in people. There are approximately six billion people alive on the earth at this moment. None of them were born with any new features that were an improvement on the current model of the human being.
Junk DNA?
Junk DNA was for a long time a 'proof' of evolution. The claim was that this DNA was leftover from our evolutionary past. Richard Dawkins proposed that this was DNA that was not actively trying to be part of the next generation, and was slowly decaying away through mutation ('The Selfish Gene' OUP 1976).
As more and more research is being done, it becomes clear that this 'junk' DNA is important genetic material with functions that are essential to our wellbeing. Junk DNA is now referred to as 'non-coding' DNA.
Darwin knew nothing about DNA. It would certainly be easier to believe in evolution if each creature (including humans) had cells containing a bit of fluid instead of the immense amount of information and programming that is actually present in each cell.
Humans share 96% of their DNA with chimpanzees. This may seem genetically similar but the difference at the chemical base level is still in the millions.**1
Evolution in it's most simplistic form may appear to be reasonable and acceptable. After all we are all animals, we are (mostly) made of the same materials and we are all born and we all die etc. If people simply accept this at face value and do not bother to investigate the complex details involved then it is easy to assume that processes such as evolution are at work.
Have a look at the Human Genome Project Information website for more information on the human genome.
References:
**1 - "What Darwin Didn't know - Geoffrey Simmonds M.D. - ISBN 0-7369-1313-0