1. Center for Psychiatry, Psychotherapy & Psychosomatics, University of Bochum, Bochum 44791, Germany.
2. Center for Psychiatry, Psychotherapy & Psychosomatics, Old Age Psychiatry Unit, University of Bochum, Bochum 44791, Germany.
3. Department of Anthropology & Department of Zoology, Miami University, Oxford, OH 45056, USA.