Since Darwin, people have speculated about the evolutionary relationships among dissimilar species, including our connections to the diverse life forms known as microbes. In the 1970s biologists discovered a way to establish these kinships. This new era of exploration began with Linus Pauling’s finding that every protein in every cell contains a huge reservoir of evolutionary history. His discovery opened a research path that has changed the way biologists and others think about the living world. In Kin John L. Ingraham tells the story of these remarkable breakthroughs. His original, accessible history explains how we came to understand our microbe inheritance and the relatedness of all organisms on Earth.

Among the most revolutionary scientific achievements was Carl Woese’s discovery that a large group of organisms previously lumped together with bacteria were in fact a totally distinct form of life, now called the archaea. But the crowning accomplishment has been to construct the Tree of Life—an evolutionary project Darwin dreamed about over a century ago. Today, we know that the Tree’s three main stems are dominated by microbes. The nonmicrobes—plants and animals, including humans—constitute only a small upper branch in one stem.

Knowing the Tree’s structure has given biologists the ability to characterize the complex array of microbial populations that live in us and on us, and investigate how they contribute to health and disease. This knowledge also moves us closer to answering the tantalizing question of how the Tree of Life began, over 3.5 billion years ago.

Microbes create medicines, filter waste water, and clean pollution. They give cheese funky flavors, wines complex aromas, and bread a nutty crumb. Life at the Edge of Sight is a stunning visual exploration of the inhabitants of an invisible world, from the pioneering findings of a seventeenth-century visionary to magnificent close-ups of the inner workings and cooperative communities of Earth’s most prolific organisms.

Using cutting-edge imaging technologies, Scott Chimileski and Roberto Kolter lead readers through breakthroughs and unresolved questions scientists hope microbes will answer soon. They explain how microbial studies have clarified the origins of life on Earth, guided thinking about possible life on other planets, unlocked evolutionary mechanisms, and helped explain the functioning of complex ecosystems. Microbes have been harnessed to increase crop yields and promote human health.

But equally impressive, Life at the Edge of Sight opens a beautiful new frontier for readers to explore through words and images. We learn that there is more microbial biodiversity on a single frond of duckweed floating in a Delft canal than the diversity of plants and animals that biologists find in tropical rainforests. Colonies with millions of microbes can produce an array of pigments that put an artist’s palette to shame. The microbial world is ancient and ever-changing, buried in fossils and driven by cellular reactions operating in quadrillionths of a second. All other organisms have evolved within this universe of microbes, yielding intricate beneficial symbioses. With two experts as guides, the invisible microbial world awaits in plain sight.

Kermit the Frog famously said that it isn’t easy being green, and in Living at Micro Scale David Dusenbery shows that it isn’t easy being small—existing at the size of, say, a rotifer, a tiny multicellular animal just at the boundary between the visible and the microscopic. “Imagine,” he writes, “stepping off a curb and waiting a week for your foot to hit the ground.” At that scale, we would be small enough to swim inside the letter O in the word “rotifer.” What are the physical consequences of life at this scale? How do such organisms move, identify prey and predators and (if they’re so inclined) mates, signal to one another, and orient themselves?

In clear and engaging prose, Dusenbery uses straightforward physics to demonstrate the constraints on the size, shape, and behavior of tiny organisms. While recounting the historical development of the basic concepts, he unearths a corner of microbiology rich in history, and full of lessons about how science does or does not progress. Marshalling findings from different fields to show why tiny organisms have some of the properties they are found to have, Dusenbery shows a science that doesn’t always move triumphantly forward, and is dependent to a great extent on accident and contingency.