Many of the tourist that are visiting Costa Rica and staying in the jungle seem to always have the same question after a few days. The question is why are animals so small and hard to see in the tropics of Costa Rica and in places like Africa they are so large and easy to see?
The answer is actually quite simple and you are often looking the answer right in the face when you ask somebody. The answer is us humans. It was 25,000 years ago that humans began to spread all over the planet. During this time you could find what is called megafauna all over the Americas. Megafauna are animals like the giant sloth which if around today would be much easier to see than the two smaller species of sloths that we find today in Costa Rica. During this period starting 25,000 years ago humans (which we are part of the megafaunas) wiped out50% of all megafauna weighing more than 100lbs through hunting.
You might be asking yourself why does Africa still have megafauna and some ofguesses are that they had more to start with and they have a long lineage of living with the environment in a sustainable form through tribal ways of lives as compared to larger societies thriving societies of the Americas with its only intentions being growth and power. Much of this is up for questioning and studies are often coming out and many now comparing the affects of climate change.
But that fact that many animals in Costa Rica are smaller is essentially better. With us humans who like to see big and take pictures of big pictures you have to remember we have a long history of being the super-predator of many animals on the planet. When we humans hunt we enjoy the biggest and largest animal. This goes for fishing also. If you think about it if humans hunt the largest of the largest then those genes will not be passed on in the lineage line. If we continue to destroy animal habitats it will only make even more sense that animals start to evolve smaller and smaller to better adapt to the resources they have left.
This is seen with trees and the the fact that humans often want to cut the largest tree to get the most amount of wood. It is here in some studies that it is seen that trees have started to grow smaller and faster to get a full life in before being cut. As the topic of evolution comes up you begin to see it is not the survival of the strongest or fittest it is the survival of those that can ADAPT to the changing environment.