Question: Does anyone have an idea how the Klingons - quite human-looking in the original series - have got their forehead furrows for which they are now famous (and easily recognizable)? I've heard rumors so far that the whole issue would be explained in the current 'Enterprise' series, but so far I haven't caught the clue.
Craig Bryant
3rd Feb 2005
Answer: It was discussed in "Enterprise". The Klingons try to make augments (super-klingons), but to do so they used the human augments DNA. This caused the Klingons whom were tested to look partly human (hence the lack of forehead ridges). It then turned into a virus which spread to many of the Klingon population. Causing them to look 'human-like'.
Craig Bryant