gradually, birthtes and industrial nations began to drop. if your children meant higher living standards. -- last children meant higher living standards. today, there is nearly 7 billion people on earth. it is estimated it will be 8 billion by 2025. can the planet support that many people? scientists are skeptical and say there will be conflicts over food, land, and especially water. >> one of the significant demographic trends is the gender imbalance in the population. in countries such as china, india, and south korea, boys outnumber girls. researchers say there will be 10%-20% more boys than girls in china and india. the traditional preference has led to an increase of selective abortions. ultrasound scans are illegal in india, many continue to use them. we visit a village in the north of the country to see the ramifications of too many men, not enough women. >> these men are passing their times. the chance that they will find a wife is not good. there are far less women than men in northern india. >> many of us are single. >> this is loc