The question of the meaning of life is the subject of an ongoing forensic examination being performed by philosophy, the social sciences, the humanities, physics, chemistry, evolutionary biology, astronomy, oceanography, religion, psychology, psychiatry, xenobiology, etc.
When a medical examiner (pathologist) looks at a dead body, she is trying to determine all she can about the cause of death (instrument used, actual fatal wounds, approximate time of death, and so forth). Homicide investigators integrate this information with the rest of the data they get from other sources (witnesses, security recordings, phone records, and the like) to try to paint of picture of who the original author of the victim's death was and why he did it.
So too are we trying to get a picture of the cause of life, and who (if there was a "who"), how, and why (if there is a "why") we (human beings and all reality) were brought into existence. It seems to me that the first step (which is far from complete) is to turn the pathologists microscope on ourselves to determine our nature, what makes us human, and how we fit into the rest of reality, which, I imagine, we hope will tell us something about cause of life.
Anyway, I suppose the short answer is to say that the meaning of life is an endless quest to discover the meaning of life.