That something is intelligence and hence a very good ability to survive and reproduce. Nothing more, nothing less. The "spirit" is created in the minds of people (not "man" or "mankind". jeez, don't you have respect for women?) when they become intelligent enough to look introvertly upon themselves. In doing so, it is easy for them to take the role of an objective observer, hence the ease our minds have with our consciousness exiting outside our bodies and floating around after we die. You'll find humans and animals are made of the same basic ingredients.