Animal Sizes and Human Benefits

There have always been large animals living on planet Earth, and there are also massive numbers of small animals. The question is whether there is a reason for each of these to exist. What is the reason for animal sizes?

Large animals require not only a lot of room but also significant amounts of food to provide energy for their massive bodies. In ancient times, dinosaurs became enormous. Their capacity to eat large quantities of plant material and spread the seeds was also huge. Today, our large animals such as rhinos and elephants are nowhere near the size of many of the dinosaurs. Still, they are large, and they consume enormous amounts of plant material. A whole ecosystem is built around these large animals, but the space available to house them is becoming smaller and smaller. Most scientific studies indicate the likely extinction of the large animal forms.

Researchers at England’s University of Southampton have been studying 15,500 mammal and bird species to ask what the future holds for large animals. Their studies show that in the next 100 years, the average body mass of mammals will shrink by 25%. As the larger animals become extinct, smaller, fertile animals will replace them.

The design of this system is amazing. In the primitive Earth, there was a need to provide resources in massive quantities over a large geographic area, and the larger animals could do that. As we dig into the fossil records of Earth, we see evidence of how successful this system was. Massive coal beds speak of conditions very different from those of today. Providing these resources required enormous animals.

Environmental change has made the production of these kinds of resources unnecessary. God designed the system in such a way that size fits the needs of the ecosystem. While we are reluctant to allow large animals to become extinct, their survival is no longer critical to the continuance of the ecosystem in which they live. Human influence has also been a factor in the reduction of animal sizes.

We find an example of the importance of small animal sizes in the oceans. Coral reefs are critical to the survival of ecosystems along the shorelines of the world. The United States Geological Survey reports that in U.S. Waters, coral reefs provide more than 1.8 billion dollars in flood protection benefits every year. The reefs are vast collections of tiny organisms which break waves, drain energy from ocean storms, and protect the land along the shoreline. In 2017 tropical storms caused more than $265 billion in damage in the United States. Much of that damage was due to the destruction of coral reefs.

God has designed animal sizes to allow them to benefit humans. He has left it to us to understand how these systems work and protect and nurture them. We live in an amazing world that has been created with wisdom and purpose. Understanding how animals benefit us will lead to protecting and caring for the world in which we live.
— John N. Clayton © 2019

Data from National Wildlife, October/November 2019, page 8.