Mutant ninja humans

I came across this interesting story today on the BBC science site; it's about DNA mutation from one generation to another.

Up until the late nineteenth century it was unknown how speciation (the branching of one species from another, i.e. mammals from reptiles or homo-habilis from australopithecines) might occur, even Darwin (1859) although he correctly deduced that it did occur had no idea what the mechanism was. It turns out that the mechanism is to do with our genes, and one of the principal ways in which variation is introduced into a gene pool is by the mutation (or changing) of our genes when we reproduce. So how do our genes mutate or change, adding and subtracting information? Well, when our DNA is copied in order to produce new DNA (i.e. of the child) sometimes that process incurs errors. Fortunately for us the vast majority of these errors are benign and harmless (or we wouldn't be here) but sometimes they inflict us with genetic disabilities and sometimes they are advantageous, longer legs, bigger brains, better eyesight etc. Advantageous DNA mutations cause the body in which they travel to be more likely to survive to reproduce and therefore tend to get passed on to the next generation, gradually becoming more numerous in the overall population; eventually the differences build up and a new species evolves.

A question has always remained, exactly how many mutations occur between one generation and the next? Now the answer has been accurately estimated by scientists in Japan looking at segments of DNA from related people going back over 200 years using ultra-modern sequencing techniques; the answer turns out to be between 100 and 200 (i.e. 150) mutations on average occur every time we reproduce. Doesn't sound like much does it, but when you think about world population over time and work the numbers you get (very) roughly 7 trillion mutations in the last 100 years, each of which could potentially change a key characteristic of a person from that of their parent.

Considering we have been evolving as a separate species for roughly 6 million years and that life itself has been evolving for at least 3 billion years, then you start to see how dramatic cumulative changes over time are not only possible but actually inevitable.