For clarity, 500 generations is easily enough for some things to shift frequency, but I agree it would be fast for a mutation to go global.  However, thrown weapons are on the order of ~20,000+ generations which is plenty of time for mutation and adaptation.<p>As to testing, I suspect we are going to get good at decoding and editing human DNA fairly soon which is going to have a lot to say about these debates.  This stuff is either there or not, when and how it showed up (or not) is a separate issue.<p>EX: Domestic cattle are also around 500 generations old and lactose tolerance has been spreading.  <a href="http:&#x2F;&#x2F;www.foodbeast.com&#x2F;news&#x2F;map-of-milk-consumption-lactose-intolerance-around-the-world&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.foodbeast.com&#x2F;news&#x2F;map-of-milk-consumption-lactos...</a> lactose tolerance: 96% in Sweden, 10% in China.