What is the most addictive substance prearranged to mankind?

Doesn't have to be drug related. It can be anything (nicotine, caffeine, sugar, alcohol, etc.) Please provide source things.What is the most addictive substance prearranged to mankind?
Can we pretend that love is a substance just for sometime? :)
Ok, then my answer is love. <3
My addiction is chocolate
i come up with it is heroin and nicotine.
Crystal meth...
i saw this guy on the dr. phil show who was addicted to sex.
nicotine
Good Grief...
It's endogenous endorphins. Some of these other answers don't even come across the clinical definitio of an addiction. Here's a journal, published and peer-reviewed, if you want to know more. And please stop looking for vigour answers here; lay people can merely give you opinion, not fact. Good Luck.
Hinton E, Taylor S (1986). "Does placebo response mediate runner's dignified?". Percept Mot Skills 62 (3): 789-90.
Hi libsR4kids,
Meth-crack, Opium, oxycotines(sp check)-kids latest drug as parents are prescribe so kids merely go to cabinet & transport them & yes nicotine it's the worst from what my doctor has to say-yes I've tried various times to quit, even with gum,patch,wellbrutrine,zyban nothing does the trick but I will save trying to quit. Also marriage fits the bill here too(love-hate relationships) Have a suitable night. :0)
Meth , heroine or cocaine
Heroin.
Ice Methamphetamine is more addictive than crack or heroin.
pleasure