Sloths have a long and diverse evolutionary history, ranging from towering giants to smaller tree-dwellers that we see today. These fascinating creatures adapted to various habitats over millions of years, evolving in size and form. While some sloths grew to be as large as elephants, others shrank and adapted to life in the treetops.

At one point, sloths were widespread across the Americas, with over 100 different species inhabiting different ecosystems. However, by the end of the last Ice Age, most of the giant ground-dwelling sloths had disappeared, leaving behind their smaller relatives.

Researcher Alberto Boscaini and his team studied 35 million years of sloth evolution, using fossil records, genetic data, and evolutionary modeling. Their findings revealed that habitat, diet, climate, and predators all played a crucial role in determining the size and evolutionary path of sloths over time.

The study emphasized the impact of habitat on sloth evolution, with forests driving the transition from large ground-dwellers to smaller tree-dwellers. Some sloth species even reverted to larger sizes in response to changing climates and ecosystems.

The extinction of the giant sloths occurred around 15,000 years ago, coinciding with the arrival of humans in the Americas. While climate change was not a major factor, human hunting was identified as the primary cause of the extinction of these colossal creatures. Smaller tree-dwelling sloths managed to survive, although their populations also faced declines.