The black type is found only in tropical or sub-tropical countries, and is usually in a primitive condition of culture, unless educated by contact with people of the white type. They follow the most primitive forms of religion (mainly fetishism), live on products of the woods or of the chase, with the minimum of work, and have only a loose political organization. The red type is peculiar to America, inhabiting every climate from polar to equatorial, and containing representatives of many stages of culture which had apparently developed without the aid or interference of people of any other race until the close of the 15th century. The yellow type is capable of a higher culture, cherishes higher religious beliefs, and inhabits as a rule the temperate zone, although extending to the tropics on one side and to the arctic regions on the other. The white type, originating in the north temperate zone, has spread over the whole world. They have attained the highest culture, profess the purest forms of monotheistic religion, and have brought all the people of the black type and many of those of the yellow under their domination. The contrast between the yellow and white types has been softened by the remarkable development of the Japanese following the assimilation of western methods. The actual number of human inhabitants in the world has been calculated as follows: By Continents.[46] Asia 875,000,000 Europe 392,000,000 Africa 170,000,000 America 143,000,000 Australia and Polynesia 7,000,000 ------------- Total 1,587,000,000 By Race.[47] White (Caucasic) 770,000,000 Yellow (Mong.) 540,000,000 Black (Ethiopic) 175,000,000 Red (American) 22,000,000 ------------- Total 1,507,000,000 In round numbers the population of the world is about 1,600,000,000, and, according to an estimate by Ravenstein,[48] the maximum population which it will be possible for the earth to maintain is 6000 millions, a number which, if the average rate of increase in 1891 continued, would be reached within 200 years. While highly civilized communities are able to evade many of the restrictions of environment, to overcome the barriers to intercommunication interposed by land or sea, to counteract the adverse influence of climate, and by the development of trade even to inhabit countries which cannot yield a food-supply, the mass of mankind is still completely under the control of those conditions which in the past determined the distribution and the mode of life of the whole human race. Influence of environment on man.