Txij li thaum ib nrab ntawm xyoo pua 20, nyob rau hauv daim ntawv chij ntawm "kev pabcuam muaj teebmeem", lub ntiaj teb tau dhau mus rau kev tshaj tawm thoob ntiaj teb kev tswjfwm rau kev txo qis kev yug menyuam thiab txo cov neeg nyob. Hauv cov tebchaws feem ntau txhim kho, qhov yug tus me nyuam twb poob qis dua theem ntawm cov neeg sib hloov yooj yim ntawm cov neeg, thiab cov neeg laus muaj vaj huam sib luag rau cov menyuam yaus lossis ntau dua li nws. Kev sib yuav tau xaus hauv kev sib nrauj thiab hloov los ntawm kev nyob ua ke. Kev ua yeeb yaj kiab tshaj lij, kev nyiam txivneej thiab neeg sib deev tau dhau los ua qhov tseem ceeb. Depopulation, tsis mythical "overpopulation" tau los ua qhov tseeb tshiab ntawm lub ntiaj teb.