Natalie P

In order to classify whether or not a species is keystone or not, often times one looks into the ratio of biomass to environmental impact. In other words, if a species has a relatively large amount of biomass present on earth and its effect on surrounding environments is also large, it can be seen that this is what can be logically expected. A large amount of biomass would be expected to require a large amount of input, and thus generate a large amount of output (any outward effect on the environment). However, an interesting situation is when there is a relatively small amount of biomass that generates a significant effect on its surrounding environment. This would define a keystone species. Humans are indeed keystone species because our relatively low amount of biomass has been responsible for colossal effects globally. For instance, we learned in class that the total mass of insects on the earth far exceeds that of human species, but the total population of insects could not have solely been responsible for what humans have accomplished. Humans appeared on earth relatively not that long ago, with respect to the age of our planet. However, our presence has been attributed to huge changes in our planet's chemical composition. We might be the best example of a keystone species there is.