Human Population Growth
SCI 230
August 16, 2013 Tammy Botten The term population growth refers to how the numbers of individuals in a population increases or decreases, with time. This growth is controlled by the rate of which new individuals are added to the population. Between the years 1800 and 1930 human population has doubled from one billion to two billion and then doubled again by the year 1975. This substantial growth in population has led to a decrease in population and biodiversity in many other species. The two types of population growth that can both be seen in human population growth are exponential growth and logistic growth. In population showing exponential growth the individual are not limited by food or disease. However in most real population both food and disease becomes important as condition becomes crowded. Logistic growth model is a more accurate representation of population growth because it takes into account that there are outside factors that may affect the growth. Logistic growth this is frequently used to model biological growth pattern where there’s an initial exponential growth period followed by leveling off as more as the population is infected so as the food supply or some other factors that limits further growths.

Exponential growth means that some quality grows a fixed percentage rate form one year to the next. If the population has a constant birth rate through time and is never limited by food or disease this is what is known as exponential growth. With exponential growth the birth alone controls how fast or slow the population grows.
One way to think about the carrying capacity is that it modifies the affect birth rate. As the population reaches the environment carry capacity the effective birth rate declines until it is 1.0 in each individuals