The growth of the human population of the globe represents the main urgent threat to human species. All other aspects of human behavior are secondary. The rate of annual growth of the human population remained very low almost/ approximately during all the few millions of years that first time man trod this planet. This growth rate, which began to rise remarkably during the eighteenth century and sharply increased during the nineteenth century, was a cause of worry only during our lifetime.

Most of the developed countries have gone through what is called a demographic transition. When industrialization began as a result of relatively assured/ guaranteed supplies of food, and the introduction of modern hygienic measures, a quick decline of mortality rate occurred largely among the newly-born and young children, while the fertility rate did not decline for some time. During that period the number of population in Europe, the United States, and Japan increased rapidly. Thereafter, the fertility rate declined to virtually match the mortality rate, and the number of population of these countries was on its way to remain stable.

But, the rest of the world was at the yoke of colonialism. The result was lack of demographic proportion which no one foresaw. The Western masters brought to large geographical zones the same hygienic measures which were effective in their own countries whereas they did not encourage the growth of local industry. In so doing, they brought down the mortality rate in varying degrees; however, they did not introduce the economic growth which would provide jobs, income, healthcare, education, better diets, and  elevate the status of women, would also generate incentives and motives of spontaneous decline in fertility, which growth accompanied in Europe, the United States, and Japan.

The large mass of the developing world still has to go through this demographic transition. As a result, the census of world population, now 4000 million, is driving toward 7000 million at the turn of the twentieth century, and is not likely to stabilize before world population is 10,000 million or more, unless other phenomena interfere, which may happen.

To put it most simply, if mankind is to live in the state of material well-being that technology can bring, and taking into consideration the size and limited resources of our planet, we are now too many / we are already just many.
 
(From: "Food and Population")