Small groups of mammals can already cooperate with each other (wolf’s, lions, monkeys etc.). In mammals, I’d guess having a queen gives a bottleneck in how fast there can be off-spring. Also if there are large returns to division of labor in child-rearing, large animals are smart enough that both parents can do this together, while in wasps the males just die (why actually?). So wasps get higher marginal returns when evolving the first steps towards being eusocial. Also smaller animals have more diverse environments and need fewer years to “locked in” eusociality and workers get born without being fertile (eusocial groups where workers are still fertile are really unstable so prone to evolve away from eusociality again when circumstances aren’t in favor anymore). Also fathers can’t be as sure of their children and the other way around leading to less cooperation if new males join in, which termites overcome by having king and queen, ants just have a queen that stores her sperm, while naked mole rats are just fine with incest?
Small groups of mammals can already cooperate with each other (wolf’s, lions, monkeys etc.). In mammals, I’d guess having a queen gives a bottleneck in how fast there can be off-spring. Also if there are large returns to division of labor in child-rearing, large animals are smart enough that both parents can do this together, while in wasps the males just die (why actually?). So wasps get higher marginal returns when evolving the first steps towards being eusocial. Also smaller animals have more diverse environments and need fewer years to “locked in” eusociality and workers get born without being fertile (eusocial groups where workers are still fertile are really unstable so prone to evolve away from eusociality again when circumstances aren’t in favor anymore). Also fathers can’t be as sure of their children and the other way around leading to less cooperation if new males join in, which termites overcome by having king and queen, ants just have a queen that stores her sperm, while naked mole rats are just fine with incest?