For natural populations the possibilities of growth are limited because of their quantities: they show a logistic growth. The quantity of population corresponds to the carrying of the environment. Contrary to animal populations the human population
grows over-exponentially: the doubling times have diminished for 2000 years. The mean annual growth rate of the population of the world was 2 per cent in 1971. Different answers are given on the question, how many can live on earth: 1 to 6 thousand
millions are calculated depending on the living standard that is based. Besides the factors food and space that limit the growth of population the problems of pollution are known since industrial times. The growing human population requires a better
technology to supply the demands for food. The technology itself brings about new problems that restrain the growth of population. The zero growth of world population brought above by birth control is regarded as a solution to achieve a longterm population