those magic changes
Day to day and throughout the day, we experience small changes in our environment. We’ re used to having a warm, sunny day but having it cool down during the night. But changes in the environment are miniscule. However, throughout Earth’ s history, large-scale changes in the planet’ s physical environment have drastically affected the evolution of life. Below are some examples of how the physical environment has affected evolution.
Continental Drift: Today, everyone knows that there are seven continents on Earth. However, the according to the theory of continental drift, about 250 million years ago, the continents were joined together as one giant supercontinent known as Pangaea. The theory says that over the course of the next 150 million years, Pangaea slowly drifted apart into seven continents. Similar to the plate tectonics, continental drift allowed isolated organisms to migrate and then evolve into different species. For example, based on studies of marsupial fossils, marsupials migrated from South America land across Antarctica, and then to Australia before the continental drift broke these land masses into separate continents. As a result, today, the majority of the world’ s marsupials are located and isolated in Australia.
Extraterrestrial Events: No, not UFOs or aliens. Yes, meteorites – meteors that managed to pass through Earth’ s atmosphere and strike the ground. A prime example is the meteorite that likely wiped out the dinosaurs 66 million years ago in the Cretaceous mass extinction. The meteorite can cause impacts that could severely impact the evolution of life. In the Cretaceous mass extinction, the meteorite deposited lots of debris into the atmosphere which blocked sunlight and changed climate. According to studies, the majority of all extinctions are results of the impact from a meteorite. Just as importantly, a new eruption of species after a mass extinction develops, and surviving species evolve to adapt to the changed environment.
Changes in Oxygen Concentrations in the Atmosphere: Since oxygen is essential to life, and since too much oxygen and too little oxygen is harmful, any significant change in oxygen levels in the atmosphere would severely impact the evolution of life on Earth. When photosynthetic organisms were introduced on Earth, the atmosphere experienced a large increase in free oxygen. However, as oxygen levels became too high, it is likely that much of life died out. At the same time, those that survived the high oxygen levels thrived, and it is thought that this gave rise to the evolution of eukaryotes.
21 VOGUE JUNE 2013
By: Talia Liu