Is there a sua sponte duty to instruct a jury on involuntary manslaughter?

However, Brothers concluded that when a defendant "indisputably has deliberately engaged in a type of aggravated assault the natural consequences of which are dangerous to human life, thus satisfying the objective component of implied malice as a matter of law, and no material issue is presented as to whether the defendant subjectively appreciated the danger to human life his or her conduct posed, there is no sua sponte duty to instruct on involuntary manslaughter. (See People v. Cook (2006) 39 Cal.4th 566, 597 ['[Defendant] savagely beat Sadler to death. Because the evidence presented at trial did not raise a material issue as to whether defendant acted without malice, the trial court was not obliged, on its own initiative, to instruct the jury on involuntary manslaughter as to victim Sadler.']; [Citation]. Otherwise, an involuntary manslaughter instruction would be required in every implied malice case regardless of the evidence." (Brothers, supra, 236 Cal.App.4th at p. 35.)