Schopenhauer's pessimism comes from his elevating of Will above reason as the mainspring of human thought and behavior. Schopenhauer pointed to motivators such as hunger, sexuality, the need to care for children, and the need for shelter and personal security as the real sources of human motivation. Reason, compared to these factors, is mere window-dressing for human thoughts; it is the clothes our naked hungers put on when they go out in public. Schopenhauer sees reason as weak and insignificant compared to Will; in one metaphor, Schopenhauer compares the human intellect to a lame man who can see, but who rides on the shoulders of the blind giant of Will.
Likening human life to the life of other animals, he saw the reproductive cycle as indeed a cyclical process that continues pointlessly and indefinitely, unless the chain is broken by too limited resources to make continued life possible, in which case it is terminated by extinction. The prognosis of either pointlessly continuing the cycle of life or facing extinction is one major leg of Schopenhauer's pessimism.
Schopenhauer moreover considers the desires of the will to entail suffering: because these selfish desires create constant conflict in the world. The business of biological life is a war of all against all. Reason makes us suffer all the more, in that reason makes us realize that biology's agenda is something we would not have chosen if we had a choice, but is helpless to prevent us from serving it, or allow us to escape the sting of its goad (compare this to the role of desire in Buddhism).
No. Can't quite believe that is the same person in those photos.