Aboutthree hundred years ago, there were approximately half a billion people in the world. Inthe two centuries that followed the population doubled, and, by 1850, there weremore than a billion people in the world. It took only 75 years for the figure todouble once more, so that now the population figure stands at approximatelysix and one half billion Each day the population of the world increases byabout 150,000.   Informer centuries the population grew slowly. Famines, wars, and epidemics, such as theplague and cholera, killed many people. Today, although the birth rate has not changedsignificantly, the death rate has been lowered considerably by various kinds ofprogress.  Machineryhas made it possible to produce more and more food in vast areas such as theplains of America and Russia Crops have increased almost everywhere and people aregrowing more and more food. New forms of food preservation have also beendeveloped so that food need not be eaten as soon as it has grown. Meat, fish, fruit andvegetables can be dried, tinned or frozen, then stored for later use.  Improvementin communications and transportation has made it possible to send more foodfrom the place where it is produced to other places where it is needed. This hashelped reduce the number of famines.  Generallyspeaking, people live in conditions of greater security. Practices such as the slavetrade, which caused many useless deaths, have been stopped.   Progressin medicine and hygiene has made it possible for people to live longer. People in Europeand North America live, on the average, twice as long as they did hundred yearsago. In other countries, too people generally live much longer than they once did.Babies, especially, have far better chance of growing up because of ncreasedprotection against infant disease. However, all countries do not benefit to the same degreefrom this program in medicine and hygiene. 
large areas of flat dry land (Para. 3)