🌍Orbit wobblesMilankovitch cycles change how sunlight reaches Earth

🧊Ice reflects sunlightmore ice → cooler → more ice

🌫️Less CO₂lower greenhouse gases in ice ages

🦣Woolly mammoththick fur, small ears

🐅Sabre-toothed catlong canine teeth

🌉Land bridgelow seas joined Asia and Alaska (Beringia)