I agree with those that say he has some type of hair system. The pictures of him in the 80s show are very, very thinning Howard. You could see his scalp in almost every picture and his hair was brown, not black. At the time, he tried the 80s rocker look and had his curly hair blown out but it would still look thin in many spots. Curly hair looks really full when it's styled straight, if the person isn't going bald.
Even though he wore his hair purposely long in the front, to hide behind it, he would constantly play and mess with his hair. Now, it's a process to watch him take his headphones on and off and the camera usually breaks away from this action.
He is too vain and egomaniacal to ever admit to it but Howard was going bald years ago.
Love the life you live
Live the life you love ~ Bob Marley