Complexity of grammatical structure has become a center of interest in recent typological and dialectological research. The contributions of the present volume discuss structural complexity from the perspective of language variation and change. Particular attention is paid to the hypothesis that languages and varieties spoken by small, isolated communities tend to display greater complexity than others.

Language complexity has recently attracted considerable attention from linguists of many different persuasions. This volume – a thematic selection of papers from the conference Approaches to Complexity in Language, held in Helsinki, August 2005 – is the first collection of articles devoted to the topic. The sixteen chapters of the volume approach the notion of language complexity from a variety of perspectives. The papers are divided into three thematic sections that reflect the central themes of the book: Typology and theory, Contact and change, Creoles and pidgins. The book is mainly intended for typologists, historical linguists, contact linguists and creolists, as well as all linguists interested in language complexity in general. As the first collective volume on a very topical theme, the book is expected to be of lasting interest to the linguistic community.

The Arthur M. Sackler Colloquia of the National Academy of Sciences address scientific topics of broad and current interest, cutting across the boundaries of traditional disciplines. Each year, four or five such colloquia are scheduled, typically two days in length and international in scope. Colloquia are organized by a member of the Academy, often with the assistance of an organizing committee, and feature presentations by leading scientists in the field and discussions with a hundred or more researchers with an interest in the topic. Colloquia presentations are recorded and posted on the National Academy of Sciences Sackler colloquia website and published on CD-ROM. These Colloquia are made possible by a generous gift from Mrs. Jill Sackler, in memory of her husband, Arthur M. Sackler.

Social isolation and loneliness are serious yet underappreciated public health risks that affect a significant portion of the older adult population. Approximately one-quarter of community-dwelling Americans aged 65 and older are considered to be socially isolated, and a significant proportion of adults in the United States report feeling lonely. People who are 50 years of age or older are more likely to experience many of the risk factors that can cause or exacerbate social isolation or loneliness, such as living alone, the loss of family or friends, chronic illness, and sensory impairments. Over a life course, social isolation and loneliness may be episodic or chronic, depending upon an individual's circumstances and perceptions. A substantial body of evidence demonstrates that social isolation presents a major risk for premature mortality, comparable to other risk factors such as high blood pressure, smoking, or obesity. As older adults are particularly high-volume and high-frequency users of the health care system, there is an opportunity for health care professionals to identify, prevent, and mitigate the adverse health impacts of social isolation and loneliness in older adults. Social Isolation and Loneliness in Older Adults summarizes the evidence base and explores how social isolation and loneliness affect health and quality of life in adults aged 50 and older, particularly among low income, underserved, and vulnerable populations. This report makes recommendations specifically for clinical settings of health care to identify those who suffer the resultant negative health impacts of social isolation and loneliness and target interventions to improve their social conditions. Social Isolation and Loneliness in Older Adults considers clinical tools and methodologies, better education and training for the health care workforce, and dissemination and implementation that will be important for translating research into practice, especially as the evidence base for effective interventions continues to flourish.

Complexity of grammatical structure has become a center of interest in recent typological and dialectological research. The contributions of the present volume discuss structural complexity from the perspective of language variation and change. Particular attention is paid to the hypothesis that languages and varieties spoken by small, isolated communities tend to display greater complexity than others.