An activist website called Negotiation Is Over is urging its followers to attack scientists.
Left-wing kooks are no different than the right wing kind, just their issues are different. Instead of global warming, they are anti-vaccine, instead of human embryonic stem cells, they are anti-agriculture.
One way fringe kooks on the left outdo their counterparts on the right is calls to violence. They're even willing to pay students if they will target biomedical students who use animals in research. Check this out: