you know people cant be called living been without them been changed i mean if a little bird didnt learn how to fly it wont live
thats why human seek changes but we must pick our changing wisely
god creature (i mean animal or human) can adapt living in a differnt way just to survive even if his mind dosent want too
smoking in a medical veiw
human body can adapt against smoking by a mechanism called metaplasia
(in brief it change the kind of cell the trachea and bronchi are replaced from the normal ciliated columnar epithelium to stratified squamous )
because it is flat and can endure gases more than columnar .
changes in body charcteristic is a really dangerous if the body adapting system cant take it anymore it might turn to cell injury and might turn to cancers .
of course adapting system differ from someone to another and we dont know how to measure thats power thats why people say (i know someone who smoke for about 50 years and he still have no cancer why whould i belive doctors and ignore what i see with my own eye"s) but you must think that you are not him you are differnt in face finger print even if its your own father.
of course cancer isnt the only thing smokeing do to your body it can affect your kidney liver like alchol spleen brain in brief every organ in your body.
researshes have said that smoker and their children have less number of sperm they can make or a normal can produce so it can cause sterility.
important.???
of course its true that every smoker already have changing in their cell the time he started smoking 
but its not too late because if they stoped thier habitual smoking the cell can turn back as they were before as a normal human(((( as its only an adaptive mechanism))) so i advice everyone to go to the nearst hospital if you are addicted to it and iam sure they well help you get rid of that habit
i am sorry if this post too long but i had too scince i knew milions of people die every year from it i wish you live happy and healthy
