I don't mean this as a negative comment aimed at you, but I always hate these sort of anecdote. The joke hinges on something we know to not be explicitly true -- ie, that if someone had more, or less, neanderthal DNA, they would be seen to be less evolved, more crude, etc. The joke relies on a misreading of the consequences for the presence of neanderthal DNA, and is only "funny" if you intentionally misread that yourself, or if you are unaware of the actual facts.