The evolutionary advantage of diploid sex
  We modify the Penna Model for biological aging, which is based on the mutation-accumulation theory, in order to verify if there would be any evolutionary advantage of triploid over diploid organisms. We show that this is not the case, and that usual sex is always better than that involving three individuals. 
A.O. Sousa, S. Moss de Oliveira and J.S. Sa Martins