physical superiority of blacks

They say the physical superiority of the US black is down to slavery. First they selected the strongest in Africa, any remaining weak ones died on the ship over. Any ones with rigorous questioning intellects of course ended up swinging from a tree on the end of a rope.

Is this true?

>>1
This is a social darwinist explanation, and it's ironic if any liberal or blacks used it.

The fact is that blacks are simply genetically physically superior in many ways, and it surely goes back much farther than US slavery. In the UK and many other Western countries the top sprinters are almost all black (although they are a tiny percent of the population), and none of their ancestors were slaves, so it's bullshit.