Digital adders form a significant part of the arithmetic unit in the processors. Many Digital Signal Processing (DSP) algorithms equally uses adder and multiplier element as its component to achieve the required arithmetic operation. Hence it is important to optimize the adder circuit in the gate-level itself to design it for the required standards. Recently there are various bio-inspired optimization algorithms which efficiently synthesize digital circuits like adders and multipliers. Optimization algorithms like Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Harmony Search (HS) has proved its efficiency in various optimization problems.