think it is a little too technically complicated to go into the but an example based on the hawaiiian papaya. it was being wiped out because it was susceptible to a virus. the yield was dropping and nothing drops the yield more than insects, fungi, bacteria, viruses that wipe out crops. think about the irish famine that wiped out potatoes. think about locusts in the bible this goes deep because these things are at war with the plants they eat. so the hawaiian papaya was acceptable by a virus and was engineered by a slick technique i will not describe but it prevented the virus from infecting the papaya meaning if you had not genetically engineered it would not have been around. that genetic engineering increased the yield of the papaya. yield means grow more on less space. that is what yield means in agricultural sense. there is really no one gene that would be the yield gene and i don't think the gmos were sold on it basis of yield but sold more on the basis of we can do this without pesticides, we can do this without plowing the soil over. they were more an efficiency and economic point of