The family connecting most of the world
Indo-European is the largest language family by number of native speakers. Reconstructed linguists have traced the common ancestor language back to roughly 4,000-6,000 years ago, likely spoken in the Pontic Steppe north of the Black Sea. From there, various groups migrated into Europe, the Mediterranean, the Indian subcontinent, and Central Asia. The major branches include Italic (Roman Latin and Romance languages), Germanic (English, German, Dutch, Scandinavian), Celtic, Balto-Slavic, Greek, Indic, and Iranian.
The internal diversity is immense. Romance languages evolved from Latin within the last 2,000 years. Germanic languages show similar recent diversification. But Baltic and Indic languages, separated from other Indo-European branches for thousands of years, retain archaic features of the ancestor language that other branches lost or transformed.
Reconstruction and prehistoric linguistics
Linguists reconstruct Proto-Indo-European by comparing cognates across branches and following regular sound correspondences. Words for family members, body parts, numbers, and animals in cognate form across distantly related languages point to shared vocabulary from the ancestral period. This reconstructed language reveals details about what prehistoric speakers knew and valued, from domesticated animals to specific crops to their social organization.