The Human Footprint: Evolving Humanity

Based off an excerpt from The Human Footprint: A Global Environmental History by Anthony Penna

This article deals mainly with the natural, meteorological, and geological causes pertaining to evolution. The first major event that set evolution in motion was the forming and subsequent breaking of Pangea. Many species went extinct when Pangea formed, but its separation led to speciation that increased the biodiversity of the planet. Next was the closing of the Strait of Gibraltar, cutting off the Mediterranean Sea from the cool Atlantic currents. This resulted in evaporation and a loss of salt that meant the freezing point of oceans increased. This led to an increase in glacier formation and a cooler global climate. This resulted in the contraction of the African rainforests and enlarging of savannahs, where the first humans came to be. The article also goes onto talk about the growth of human intelligence as humans evolved larger brains. This is evident from the increase in skull size as a general trend and the evidence of increasing use of tools. Bipedalism helped aid tool usage and migration.

It is evident from this article that geological phenomena put human evolution in motion, but what the article doesn’t mention is how the ideas behind geological phenomena are also partially responsible for the theory of evolution itself. Charles Lyell wrote a book called The Principles of Geology, that outlined some of the things the article talked about. Mainly that topography changes over time. Charles Darwin read this book during his voyage on the HMS Beagle, and began to formulate a hypothesis around the idea that if land can change over time, then the creatures living there must change also. As Darwin circumvented South America, he observed this. Eventually he reached the Galapagos Islands, where the Theory of Evolution was formulated and eventually made official.