Your answer may vary as this is partially opinion and partially creative thinking.
Work Step by Step
You can argue most of the factors in Figure 53.18, with predation being the only one that is less applicable to humans than the others. Competition for resources—or just their distribution –is an ever growing threat to humans, as is toxic waste and territoriality as our armed forces become more and more advanced and our capability for destruction on a large scale grows. Disease has been a factor since humans began living in larger population centers. Intrinsic factors may be a factor for humans as highly-resourced populations tend to have declining birth rates, and there is some evidence that we also see hormonal and fertility changes in these populations that inhibit reproduction.