As a promising technology that enables ubiquitous computing and leads IT industries of next generation, sensor networks (SN) are foreseen to expand and populate the globe in such a way as the present Internet does. In this scenario, new challenges appear with such massive deployment, as the constant interaction of nodes and networks will transform them in dynamic entities that will need to evolve with their environment. In this paper, we discuss the future of sensor networks defining the concept of evolvability and its application. We also describe ANTS, a complete new architecture for wireless sensor networks, as our implementation to solve the challenges imposed by this evolvable future. Key Words. Sensor Networks, Evolvability, Operating Systems, Middleware, Localization, Synchronization, Security, Network Protocols