A new study, part of National Geographic's Genographic Project, shows modern-day Uros people in Peru and Bolivia descended from the earliest settlers at Lake Titicaca.
These prolific fish are already widespread in stretches of the Illinois and Mississippi rivers, where they have severely overwhelmed native aquatic communities.
Beneath the ice crust of a frozen ocean, microscopic algae and bacteria thrive. As the Arctic becomes ice-free, they will play a new role in Earth's ecology.