The columbian exchange irrevocably

homogenized the world's biological

landscape. what does john green mean by

this?

Ever since Columbus set foot in the Americas, the number of endemic species, that is to say, species that only live in a specific geographical area has diminished, while other species have thrived, in the five continents.

For example, the Columbian Exchange led to the cultivation of a South American crop: the potato, across Europe and Asia, where millions of people in cold climates where able to avoid famine by feeding themselves with it.

Another biological homogeneization process occurred with disease vectors: before the Columbian Exchange, diseases such as measles or smallpox were unheard of in the Americas. When Europeans arrived, Native Americans did not have defenses against this illnesses, and the majority of them perished because of contagion (over 90%).

Nowadays, these diseases are present all over the world, but thanks to vaccines, they do not kill as many people as before.

the titanic was filmed in canada and si my fav