The Replacements

S1 E4: For every human alive 12,000 years ago, two thousand of us live on the planet today. As we multiplied, people spread around the world, conquering virtually all the planet's ecosystems. But we didn't do it alone. In this episode of Human Footprint, Shane meets “The Replacements:” a group of animal and plant species that accepted humanity's helping hand, hitching their destinies to our own.