I am the master of my body. I order you to stop beating now!
This is a "play of the mind". Please don't misinterpret as personal.
Earth is overpopulated and human beings are running out of resources. Will evolution enable human beings to consciously stop their heart from beating and die peacefully, with the benefit of reducing population pressure?
Well it is difficult to imagine. The way evolution works, only traits that are beneficial to a better survival will strengthen over generations. Even if the trait of dying was beneficial for the society as a whole, it would not survive to the next generation because there would be no offspring to carry it further.
Let us imagine that this gene mutation came tied with another one, more evolutionary positive, out-weighting the former. At some point, people would discover that by focusing their mind very strongly on contracting their heart muscle, they could override their biological peacemaker and trigger a contract-and-don't-release deadlock.
Following the discovery of this new ability, the human society would deeply change. Mental health would become a major topic in any important commitment.
There would be a mandatory insurance capital dedicated to the refund of people being wronged by the voluntary death of someone, and most commitments would feature a minimum insurance threshold for application: studies, jobs...
For activities where failure can threaten the lives of others (e.g., aircraft pilot, military), those positions would require people to have an implantable cardioverter-defibrillator .
In dating, the amount of life insurance would be critical in seduction. There would be a dedicated field in the form for profile creation on dating website. Just beside age, and hobbies.
Laws would be changed to hand out misdemeanors to people for involuntary psychological violence (e.g., stopping a friendship with no reason given).
What do you think? I bet there is already one or several books about this topic. This topic was proposed to Reddit .
Don't forget to watch this
Surpopulation is not really an issue? Do not forget to watch this .
 Quora, "Is it possible to consciously stop your own heart?", https://www.quora.com/Is-it-possible-to-consciously-stop-your-own-heart
 Skeptic Meditations, "Can Yogis Stop Their Heart?", http://skepticmeditations.com/2015/05/17/can-yogis-stop-their-heart/
 Wikipedia, "Implantable cardioverter-defibrillator" article, https://en.wikipedia.org/wiki/Implantable_cardioverter-defibrillator
 Reddit post, https://redd.it/3iu7ya
 Hans Rosling, "Don't panic" documentary, https://vimeo.com/79878808