@steverocky @Wifiwits @ktdoggett because what you’re not getting is that the mechanism of bone healing is the same in survivable breaks— say an arm or rib or finger— as a femur break. You benefit from ANY bones healing, then you can evolve the ability and once your body learns it, automatically regens all bones since it’s all the same material to your biochemistry. Your narrow focus on just femurs has inadvertently created a logical trap for yourself.