Exaptation is a fundamental concept in evolutionary biology where a trait that evolved for one particular function is co-opted or repurposed to serve a different function. The term was coined by paleontologists Stephen Jay Gould and Elisabeth Vrba in 1982 to distinguish these features from adaptations (traits that evolved specifically for their current role).
- Original function: Thermal regulation and display
- Exapted function: Flight capabilities
- Evidence: Fossil record shows feathers in non-flying dinosaurs
- Original function: Aerial flight
- Exapted function: Underwater "flight" and swimming
- Notable: Demonstrates how selective pressures can repurpose existing structures
- Original function: Basic vocalization and motor control
- Exapted function: Complex speech and language
- Includes: Both physical structures and neural pathways
- Original function: Jaw bones in early vertebrates
- Exapted function: Sound transmission in modern mammals
- Evolutionary significance: Major transition in vertebrate evolution
- Computer hard drives from phonograph technology
- Touch screens from ATM interfaces
- GPS from military navigation systems
- Social media platforms from college networks
- Cloud storage from server infrastructure
- Streaming services from mail-order rentals
| Feature | Adaptation | Exaptation |
|---|---|---|
| Evolution Path | Direct evolution for current function | Co-opted for new use |
| Selective Pressure | Direct pressure for current function | Indirect path to current function |
| Development | Specifically evolved traits | Repurposed existing traits |
The concept of exaptation highlights several important aspects of evolution:
- Non-linear development: Evolution often works with existing structures
- Opportunistic nature: Traits can serve multiple functions
- Innovation pathway: New functions can emerge from existing traits
- Complexity development: Simple structures can evolve into complex systems
- Drug repurposing (e.g., Viagra was originally developed for hypertension)
- Surgical techniques adapted from other fields
- Medical imaging technologies adapted from space exploration
- Artificial Intelligence algorithms repurposed across different domains
- Mobile phone technology adapted for healthcare monitoring
- Social media features adapted for emergency communication
Understanding exaptation has important implications for:
- Evolutionary Biology: Understanding how complex traits develop
- Innovation Research: Identifying new uses for existing technologies
- Drug Discovery: Finding new applications for existing compounds
- Technological Development: Inspiring new applications of existing solutions
- Gould, S. J., & Vrba, E. S. (1982). Exaptation—a missing term in the science of form
- True, J. R., & Carroll, S. B. (2002). Gene co-option in physiological and morphological evolution
- Wagner, A. (2011). The origins of evolutionary innovations