genes

[Dejavu8795]

the major role of genes is to pass on what?

[redhead23]

plays a key role in body size , longevity

[wildwood]

Parental characteristics.

[chakka35]

Themselves

[retrochoir]

Yes, copies of themselves. Fortunately for us, sometimes mistakes are made in the copying process. This results in a mutant gene which (in simple terms) can sometimes be 'better' than the original gene in the sense that it gives its organism a better chance of survival which in turn means its organism is more likely to reproduce i.e. copy the gene again to the next generation. This is a vague description of natural selection which is the cause of Evolution. As you've probably gathered I am not an expert but I hope this helps.

[chakka35]

You're right, retrochoir, about the 'fortunately for us' bit.

I'm always amused when people say 'In a perfect world...' because in such a world we would not exist. The original very simple genetic code of extremely primitive life would have been passed on for ever without any of those errors (mutations) which drive evolution. The only other life (not guaranteed) would be a different, equally primitive form which had also come about accidentally. So thank heavens for an imprefect world!

[eifionlewis]

Mutations truly are the spice of life :o)