The prologue of Ivan Schwab’s timely testimony to evolution marks life’s beginning on earth at 3750 million years ago, followed closely in time by photoreception; logical because virtually all life depends directly or indirectly on sunlight. Indeed, the premise of Evolution’s Witness is that photoreception endured the test of time, thriving in multiple life forms many still in existence today. With beautiful illustrations and engaging prose, Professor Schwab tracks the course of photoreception through time, allowing readers to marvel at Darwin’s Theory and fully comprehend the evolution of the eye.
The inside cover of Evolution’s Witness is a color-coded list of geologic time spanning more than 4 billion years from the Hadean Eon to Cenozoic Era and present day. Major events are listed for each time frame, and page margins for each chapter are color-coded to correspond to colors in the geologic timeline. The first three chapters set the stage for ocular evolution with the birth of life, onset of photoreception, transition from single-cell prokaryotes lacking nuclei (e.g., cyanobacteria) to eukaryotes (e.g., Euglena with an eyespot to capture light and propeller-like flagellum to move toward or away from light), and finally multicelled metazoa. Fundamental evolutionary developments during this time, conserved and passed on through lineages, included rhodopsin-like molecules with light-catching retinal chromophore and opsin to confer spectral sensitivity, coupled with a primitive form of the PAX6 master gene essential for eye formation. Beyond these invariances, it is proposed that the eye evolved numerous times, yielding diverse morphology and specializations critical to flourish in myriad settings with distinct survival needs. Each subsequent chapter is a unique episode in time detailing eyes characteristic of that era and ultimately spanning millions of years, species, and morphologies ranging from eyespots to compound and camera eyes. Amazing color photos on nearly every page ensure a vivid trek through evolution of the eye.
An all-inclusive glossary and chapter-specific references accommodate diverse readers of this captivating text. Appendices detailing evolution of ocular muscles, retinal blood supply, cornea, lens, accommodation, and photoreceptors prove in valuable for specialists and generalists alike. Evolution’s Witness, in whole or part, is an essential mainstay for multiple disciplines, irreplaceable for vision scientists and eye care professionals.
Jeff C. Rabin
San Antonio, TX