Whether you notice it or not, the planet we call home also supports incalculable life, ranging from the tiniest of microscopic bacteria to the largest of towering trees. Each living organism occupies a specific niche in its environment. Still, survival comes at a cost in our world where resources such as food and space are often limited.
This is where adaptation -- when an organism becomes better matched with its current environment -- comes into play. In general, adaptations can be structural (meaning an organism undergoes bodily changes to survive) or behavioral (when a specific behavior increases an organism's chances of survival).
Adaptations, such as birds migrating south for the winter or animals using tools to forage for food, occur at the individual and population levels, as we'll learn later on.
So what causes organisms to adapt?
Environmental factors -- including competition for resources, predation, infectious diseases, climate and seasonality -- play a large role. As we learn more about how life adapts to its environment, we'll discover that some adaptations occur in a few generations whereas others take many generations to fine-tune. To begin, let's look at digestion.
Why do humans rely on foods like fruits and vegetables to survive while other organisms such as bacteria thrive by processing carbon? Read on to learn about adaptive digestion.