You can read an interesting excerpt from the new Cambridge Handbook of Age and Aging online: "The field of gerontology has accumulated vast amounts of data over the past several decades, creating a goldmine of potential theoretical knowledge. Yet explicit theory development has lagged - prompting some to observe that gerontology remains data-rich and theory-poor ... Several factors may have impeded theoretical progress in gerontology [including] the difficulty of crossing disciplinary boundaries in order to create multidisciplinary explanations and interpretations of phenomena of ageing." This is a point often made by biomedical gerontologist Aubrey de Grey - biomedical research is very much in need of cross-field pollenation, analysis and synthesis.
Link: http://www.cambridge.org/uk/catalogue/catalogue.asp?isbn=0521533708&ss=exc