No matter how much we ignore it, human population is a major global problem. With it, the question arises: how many people can the earth really support? Many scientists believe that the earth’s human capacity maxes out at 9-10 billion people. A sociobiologist at Harvard University says in his book, “The Future of Life” (Knopf, 2002) , that “the constraints of the biosphere are fixed.” Today, excessive population growth has led to issues of insufficient supplies of food and freshwater for the 7 billion people the earth holds. We are taking more than the earth can naturally replenish, and we are doing this at record speed. If everyone on earth became vegetarian, the estimated amount of people the earth could support in reference to it’s food supply swells to approximately 10 billion people. However, food supply is not the only problem population capacity faces. Our earth’s holding capacity is also stunted by the nitrogen cycle, or “available quantities of phosphorous, and atmospheric carbon concentrations”. It is predicted that our population will hit 9 billion people by 2050, and 10 billion by 2100. However, this should not be the end for human life as we know it. The UN predicts that somewhere along the line, our population will make “a U-turn”. So, there is still hope in other words.