This paper explored the question: “Is there an effect of Human Population Growth on Propithecus verreauxi Population in Madagascar from 1985 to 2000?”. With the specific focus of Madagascar as the field of study and Propithecus verreauxi as the species, an investigation was carried out with controlled geological space focusing on a unique ecological system and the relationship between human population and the species. Using database analysis, data from genetic analysis and field study was used to estimate the lemur population at different time points. Abiotic condition data was also collected and was used for possible explanations in the results. Analysis on the data revealed an indirect correlation between Propithecus verreauxi population and Homo sapiens population. Calculations of Pearson R-values suggest a lack of correlation between the annual precipitation and Propithecus verreauxi population, an indirect correlation between the annual temperature and Propithecus verreauxi population, and a direct correlation between forest area and Propithecus verreauxi population. Besides drought and deliberate hunting, a reduction in forest area was shown to be the most important factor in the decreasing numbers of Propithecus verreauxi. A reduction in resources and space such as forest area as a result of human disturbance could potentially lead to a competition, which would then lead to a reduction in lemur population through natural selection. Other reasons could be more subtle and less influential such as the influence of temperature and humidity on the population, which could also be a result of human impact on the environment on a global scale.