Thanks for that Charlie. My general point is that when chromosome 'anomalies' like this occur, the general evidence is that they lead to genetic disorder and high levels of infertility. For example when you cross a horse that has 64 chromosomes with a donkey that has 62, you get a mule with 63. But the mule is infertile - the only way to get a mule is cross-breeding a donkey with a horse.

This appears to be a generality in nature. Where it happens, it's always proved to be an evolutionary disadvantage to the species. So my general point within humans was that when you consider all the changes needed to get from 48 to 46, it looks like an incredibility that this could happen naturally, such that it propagated throughout the entire human race. Unless that is, the changes were engineered.

It's a fascinating exploration.