In 2009 Dr Paul Andrews published a paper with Dr Andy Thomson in Psychological Review that argues depression may be an evolved emotional response to complex problems, and its function is to promote changes in body systems that promote analysis of those problems. Their paper "The bright side of being blue" addressed various levels of evidence in regards to this argument, known as the "analytical rumination hypothesis" (ARH). By reducing the amount of time spent in otherwise distracting activities unrelated to the depressive episode, and by producing psychomotor changes that reduce exposure to distracting stimuli, depression may be able to sustain analysis of complex problems in one's life. In 2007, Dr Andrews performed an experiment demonstrating that complex analytical tasks that require sustained attention are able to induce sad mood, and this sad mood positively correlates to the successful solving of the same analytical problems. Consistent with the ARH, sad mood may be allocating limited attentional resources towards these problems, increasing one's sad mood, but this allocation aids in solving the depressogenic complex problem. Complex problems in one's life that ultimately impact reproductive success, such as financial difficulty or relationship troubles, may require more focus and attention in order to be solved, which reduces attention in other activities. This paper was languishing in obscurity until Dr. Richard Friedman put it on the pages of the New York Times.