Patañjali's Yoga Sūtra systematizes in 196 aphorisms a tradition of somatic and contemplative practice of pre-Vedic origin, structuring it into eight limbs (ashtanga): yama (ethics), niyama (personal discipline), āsana (posture), prāṇāyāma (breath control), pratyāhāra (sensory withdrawal), dhāraṇā (concentration), dhyāna (meditation), and samādhi (absorption). The system describes mechanisms of voluntary regulation of the autonomic nervous system, sustained attention, and modulation of the stress response that modern neuroscience has begun to validate experimentally. Āsana and prāṇāyāma practices have documented effects on heart rate variability, cortisol, and vagus nerve activity. Western appropriation of yoga from the 20th century onward extracts the physical postures (āsana) decontextualized from their original system, reducing a complex psychophysiological regulation system to a flexibility and fitness practice. This decontextualization is documented as a case of cultural biopiracy: Western companies have attempted to patent āsana positions described in two-thousand-year-old Sanskrit texts.