For the first time ever, we can track the number of genetic mutations in each generation of a human family. Humans are mutating at a downright glacial pace, with a shockingly tiny number of mutations passed on in each generation.
Researchers have previously used various indirect methods to estimate just how many mutations are passed from parents to children, but it's only now that researchers at the University of Montreal have been able to study the complete genomes of two families - each composed of a mother, a father, and a child - and figure out just how fast human mutation really is.
As lead researcher Philip Awadalla explains, the result fell far short of previous estimates:
"Your genome, or genetic code, is made up of six billion pieces of information, called nucleotides. Three billion come from each parent, and based on indirect evolutionary studies, we had previously estimated that parents would contribute an average of 100-200 mistakes in these pieces of information to their child. Our genetic study, the first of its kind, shows that actually much fewer mistakes – or mutations – are made. In principle, evolution is happening a third as slowly as previously thought."
The study also tested the theory that most genetic mutations come from the male. The reasoning behind this idea is that males create far more sperm than women do eggs, which provides many more opportunities for errors to occur during cell replication, which of course is all a mutaiton really is. But this study didn't provide clear support for that, as Adawalla explains:
"We saw that the number of mutations from the male was less than the number of mutations from the female in one of the families. This doesn't mean that we're throwing the theory out the window, it simply means that the mutation rate is extremely variable from individual to individual, or even that some people have mechanisms that reduce the likelihood of mutations."