Phylogeny and Animal Models: An Uninhibited Survey
INTRODUCTION This chapter examines hum an obstructive sleep apnea (OSA) in relation to air breathing in vertebrates. It begins by examining the origins of air breathing and showing that the neuromuscular factors that were responsible for air breathing in the earliest terrestrial vertebrates play a key role in m odem sleep-disordered breathing in man. The chapter considers the evolution of the pharynx in prehuman species, documenting trends in the structure of the facial framework and pharyn geal dimensions. We show that these trends in hominids underlie hum an speech but predispose Homo sapiens to sleep apnea. Finally, we review animal models of obstructive sleep apnea to discover why it is a uniquely hum an disorder. We label our survey uninhibited to emphasize its diversity of informational sources and to acknowledge the speculative nature of our discussion. Our lack of inhibition reflects our exuberance for the topic, which we hope is shared by the reader.