Why are the Anatolian languages important to the study of Indo-European languages?

The Anatolian languages are of paramount importance to the study of Indo-European languages because they represent the oldest attested branch of the family, providing critical data for comparative grammar.12

Their significance is highlighted by several key factors:

• Laryngeal Theory: The discovery of the consonant h(h) in Hittite provided direct empirical evidence for the "laryngeal" consonants previously hypothesized by Ferdinand de Saussure based solely on internal reconstruction.3
• Archaic Structure: As the earliest recorded Indo-European languages, they challenge traditional reconstructions of Proto-Indo-European. Their apparent lack of certain features—such as the feminine gender or specific verb tenses—has led to the Indo-Hittite hypothesis, which suggests Anatolian may have diverged from the parent language earlier than other branches.2
• Comparative Evidence: The integration of Hittite data into the broader Indo-European framework was a major 20th-century development, confirming the Indo-European affinity of these languages through shared nominal and verbal systems, such as specific case endings and conjugation patterns.41