PU35CH10-Bernstein ARI 22 February 2014 18:29

Biological Diversity and Public Health Aaron S. Bernstein Center for Health and the Global Environment, School of Public Health, Harvard University, Boston, Massachusetts 02115

Division of General Medicine, Boston Children’s Hospital, Boston, Massachusetts 02115; email: aaron.bernstein@childrens.harvard.edu

Annu. Rev. Public Health 2014. 35:153–67

First published online as a Review in Advance on January 2, 2014

The Annual Review of Public Health is online at publhealth.annualreviews.org

This article’s doi: 10.1146/annurev-publhealth-032013-182348

Copyright c© 2014 by Annual Reviews. All rights reserved

Keywords

climate change, emerging infectious diseases, natural products, undernourishment, pollinators

Abstract

In the wake of a species extinction event unprecedented in human history, how the variety, distribution, and abundance of life on earth may influence health has gained credence as a worthy subject for research and study at schools of public health and for consideration among policy makers. This article reviews a few of the principal ways in which health depends on bio- diversity, including the discovery of new medicines, biomedical research, the provision of food, and the distribution and spread of infections. It also examines how changes in biological diversity underlie much of the global burden of disease and how a more thorough understanding of life on earth and its relationships has the potential to greatly alleviate and prevent human suffering.

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PU35CH10-Bernstein ARI 22 February 2014 18:29

Eukaryote: a single-celled or multicellular organism that possesses membrane-bound nucleus/nuclei and membrane-bound organelles

INTRODUCTION

The discipline of public health, in its quest to jointly prevent disease and promote health, has over time increasingly confronted the relevance of species other than Homo sapiens to its work, and for good reason. Biological diversity, or biodiversity for short, a term that refers to the variety of life, including species, the genes they contain, and ecosystems they form, underlies much of what keeps people healthy, from adequate and clean water, to food, medicines, and freedom from infectious diseases.

Attention to biodiversity as it pertains to human health has grown as present rates of species extinction, a key indicator of the status of the biosphere, are 100 times, and in some cases 1,000 times or more, faster than those observed in the fossil record (57). The rapid pruning of the tree of life has raised sober consideration about whether the earth’s sixth mass extinction event has commenced (4). To put this prospect in perspective, the earth’s most recent mass extinction transpired 65 mya when an asteroid struck the earth and wiped out the dinosaurs as well as more than half of all species with them. As humans have evolved as part of the web of life, this loss of biodiversity raises major questions about how humanity will fare as the rest of the living world is thrown into tumult.

This article presents an overview of biodiversity and how it is assessed and then turns to several key interfaces between biodiversity and health, including the discovery of new medicines from natural products, advances in biomedical technology made possible through harnessing unique evolutionary adaptions, the provision of food and food security, and the prevalence and spread of certain infectious diseases.

BIODIVERSITY UPSIDE DOWN

Assessment of earth’s biodiversity has most often been performed by counting species. To date, about 2 million species have been identified, but the total number may be four or more times as many (14, 49). Little more than their names, however, may be known about many of these creatures. Just over 65,000 species, for example, roughly 4% of those known, have received any scrutiny on their conservation status (31). Astonishingly, far more is known about the details of molecules within individual organisms, such as genomes, than is known about the variety of organisms that inhabit the planet, and this despite the latter having been studied for centuries more.

Biological diversity consists of more than just the diversity of species. Advances in molecular biology in the late twentieth and early twenty-first centuries have enabled the assessment of biodiversity at a genetic level and have begun to change the way in which biodiversity is understood. In a seminal paper published in 1977, Carl Woese and George Fox presented a model of life that sorts organisms into three domains, instead of the traditional five kingdoms, on the basis of their ribosomal RNA composition (85). Their analyses revealed that two-thirds of all the genetic diversity on earth resides in single-celled organisms that comprise the prokaryotic and archaeal domains (see Figure 1). The rest of life, including all plants, animals, and fungi, are subsumed into the third domain, the eukaryotes. The three domain model turns the traditional five kingdom view of life, which posits that life’s diversity is mostly eukaryotic, on its head (see Figure 2).

Genetic diversity matters to health in many ways, some of which are presented below, and the recognition that most of it derives from microbial organisms has brought about a sea change in understanding about how the diversity of life influences health (see also Appendix 1: Microbial Di- versity, the Human Microbiome, and Health). Another emerging area of research that pertains to biodiversity and human health involves understanding the ramifications of human transformation of earth’s ecosystems. Lesser biodiversity within and among ecosystems reverberates in agricultural productivity and in the transmission of infectious diseases, topics that are also considered below.

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