1. Indo-European: With over 3 billion speakers, Indo-European is the largest language family. It includes languages like English, Spanish, Hindi, Russian, German, French, and many others. It is thought to have originated in the Pontic-Caspian steppe around 4500 BCE.
2. Sino-Tibetan: The second largest language family, with over 1.4 billion speakers. It includes languages like Mandarin Chinese, Tibetan, Burmese, and many others. This family originated in the Yellow River Valley in China, and is thought to have diverged around 7000 BCE.
It's worth noting that these figures are estimates, and there is some debate about the exact number of speakers in each family.