PREFACE: Read This First!

We, the authors, have borne witness to the extraordinary transformation of a scientific field, which we will refer to here as circadian biology.  It’s the biology of adapting to life on our rotating world, to the Earth’s 24-hour rhythm of day and night.  Circadian biology is not really a sub-discipline of biology – like zoology or immunology or genetics – but instead spans the whole of the biomedical sciences and across biological kingdoms.  Not surprisingly, the field has attracted considerable popular interest as well as new immigrants seeking further study or applications – students, investigators, and collaborators – ethologists, physiologists, oncologists, urban architects, agriculturists, wildlife conservators, and more.  This new diversity is exciting and invigorating!

But there’s a problem, at least as we see it.  Formal courses in biological time and timekeeping are still uncommon in undergraduate, graduate, and medical curricula.  So, newcomers may have little or no foundational knowledge on the essential principles and practice of circadian biology, no framework upon which to incorporate their disciplinary experience and expertise.  Our language, data visualization, and concepts might seem as daunting as the science itself.  If this is you – whether your aim is to conduct research, collaborate/communicate with others, or understand advanced experimental literature – then this book is meant for you.  It is not intended to be a popular book (of which there are already several); or as an up-to-date manual of experimental methods and discipline-specific approaches (about which you are likely already expert in your area); or as a comprehensive textbook (although a new one is certainly past due).  Instead, our intention is to provide you with a Road Map – consider it a launching pad, jump start, gateway, or primer – as a first (and hopefully engaging and helpful) step to enter the field and as an entrée to its now voluminous literature.

We strongly recommend you read the book in order, from beginning to end (you know, just like an old-fashioned book!); or perhaps it could be used as a template underpinning a series of didactic sessions for laboratory members and students.  Our Road Map is really not that long, at around 13,000 words, with the three chapters building on one another in succession. Make sure to read the figure legends as well.
Along the Road, you will find links to Points of Interest, denoted by ; these indicate supplementary (bonus) material meant to clarify, expand, comment, or illustrate the main text without interrupting its flow. They are self-contained (you will not be dropped directly onto the internet), and at the end of each Point of Interest is a “home” icon that will send you back to the main text. Consider the Points of Interest as informative footnotes and selected (rather than complete) references intended to serve as portals for further learning. And finally, note that this electronic platform does include a Search function (see infographic at right, click to enlarge).

We must apologize in advance that our presentation leans heavily on mammals and mammalian circadian timekeeping; we do include some material on insects (especially Drosophila) and birds, as well as in the Points of Interest, but in general we admit that bacteria, unicellular eukaryotes, fungi, and plants really do get short shrift.  And to keep the main text short and readable, we were forced to decide – from all the incredible work in this burgeoning field – what we felt was crucial for you to know as part of the Road Map.  For that, we admit relying on our subjective views, based on our combined 70 person-years in the field, and for which we take full responsibility.

Lastly, we wish to thank each other for many profitable hours of animated and fruitful discussions, none of which resulted in (significant) bodily injuries to either of us.  We greatly appreciate the insightful comments of Danny Forger, Mary Harrington, Renske Lok, Laura van Rosmalen, Paul Taghert, and Dave Weaver on an early version of the manuscript. We are grateful to Riëtte van Zwol for her expert transformation of the Road Map to an original cover design and Nicole Mangum for administrative support.  And we are indebted to the Groninger University Fund’s WETEX grant and the University of Groningen Press for partial funding of our project, and to Margreet Nieborg and Pieter van der Veen of the Press for their expert and invaluable advice and support, without which this Road Map would not have seen the light of day.

Roelof and Bill.