The Theory That Changed Everything, by Philip Lieberman (preface)

T H E T H EO RY T H AT C H A N G E D E V E RY T H I N G “On the Origin of Species” as a Work in Progress

PHILIP LIEBERMAN

THE THEORY THAT CHANGED EVERY THING “ON THE ORIGIN OF SPECIES” A S A WO R K I N P RO G R E S S

PHILIP LIEBERMAN

COLUMBIA UNIVERSIT Y PRESS

New York

PREFACE

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he more we learn, the more it becomes evident that the insights and observations conveyed in On the Origin of Species continue to guide our understanding of biology, evolution, and how we might act in matters of general interest, some bearing on our very existence.

Charles Darwin was a keen, curious observer who possessed a quality of mind that enabled him to see the connections among seemingly unrelated natural phenomena and human endeavors. His voyage on HMS Beagle was, as he put it, “the most important event in my life, and has determined my whole career.� Darwin came in contact with the indigenous people of Tierra del Fuego, who lived in circumstances far removed from those of his prosperous family and acquaintances, but he nonetheless discerned the qualities that made it clear to him that all people are brothers and sisters. He saw animals and plants outside the range of what is found in England and Scotland and the fossil remains of creatures that no longer live on earth.

When Darwin first boarded the Beagle on December 27, 1831, he firmly held to the belief that God had created the world and all its forms of life. On his return to England four years later, he started on the journey in his mind’s eye that led to the theory that changed

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how we view the evolution of all forms of life and their place in nature. His theory was controversial from the day of its publication in 1859 and remains so today. Darwin departed from the view that God had created the world and all forms of life in a week or else had set in motion a master plan that over time produced new forms of life, extinguishing others. The course of evolution instead was happenstance based on variation and chance. No two beings are identical. Variation always marks the creatures or plants that constitute a species, including the individuals who constitute the human species, Homo sapiens. Darwin did not know how or why variations occurred—why some roses were redder than others or why some people were taller or could run faster—but he thought that natural selection was the primary mechanism for the “transmutation” of species: evolution.

Natural selection is a simple concept. Any heritable variation that results in a living organism’s having more descendants tends to be preserved, providing a “selective advantage” in the “struggle for existence.” However, ruthless competition and brute strength were not the keys to success in the Darwinian struggle for existence, a concept that has been misinterpreted and misused to justify exploitation and greed. Cooperation yields benefits, and, as Darwin stressed, small changes can drive natural selection. One of the incremental results of natural selection is evident on the shelves of your supermarket. If your ancestors lived in a culture that herded cows, sheep, or goats, you will most likely skip the lactose-free selections because natural selection has conferred on you adult lactose tolerance. Being able to add milk to our diet conferred an advantage in the “struggle for existence”—making some individuals and their children more likely to survive. If your ancestors did not live in such a dairy culture, you may need to purchase lactose-free products.

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However, Darwin was wrong in thinking that the pace of natural selection is always slow and gradual. Had he remained in the Galapagos for a decade rather than a few weeks, he might have observed changes occurring in the finches’ beaks as they adapted to harder- or softer-shelled nuts. But Darwin pointed out that natural selection wasn’t the only process that drove evolution. “Recycling,” adapting an organ to do something new, could abruptly change the course of evolution. And he borrowed from the grandfather he had never met, Erasmus Darwin. Erasmus, in his book Zoonomia, published decades before Darwin was born, studied the development of animals from their embryological state onward, which to both Erasmus and Charles Darwin demonstrated the continuity of evolution.

Erasmus also thought that “acquired features,” direct effects induced by the environment, could be inherited—the “just-so” story of how giraffes got long necks because they stretched to reach leaves on higher tree branches. Charles Darwin also borrowed that concept. In the twenty-first century, we’re seeing that it isn’t always a just-so story. I will attempt to demystify current “Evo-Devo” studies aimed at identifying transcriptional and epigenetic factors coded in your DNA that determine why you don’t look or think like a chimpanzee, even though you share virtually all of its genes. Epigenetic effects, for example, caused the grandchildren of women from nineteenth-century Sweden whose diet suddenly changed from famine to feast, or the reverse, to die thirty years sooner than other people.

I have organized my book as though it were the script of a documentary film aimed at presenting Charles Darwin’s insights. The “talking head,” whenever possible, is Darwin, in passages drawn from On the Origin of Species, the short autobiography that he wrote for his children and grandchildren, and his letters. The exotic

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settings that Darwin encountered throughout South America and in the Galapagos Islands set his mind in motion, but he saw parallels and conducted experiments in the familiar surroundings of early Victorian country life. These and contemporary examples show that Darwin’s insights apply with equal force to issues that are shaping your life and the lives of your descendants.

Darwin stressed the complex relations that exist among forms of life far removed in the scale of evolution from one another and between those life forms and the environment. He pointed out the synergy that exists between an ecosystem and evolution. As the environment changes, whatever might confer a selective advantage changes; so as we humans change the world, it changes us. And if we don’t take care, it could be the end of us.

Providence, R.I. February 3, 2017

ACKNOWLEDGMENTS

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’ve drawn on the research of my colleagues over the course of more than fifty years as well as on people I have met only through their books and papers. I cannot tell Elizabeth Bates, Arend Bouhuys, Franklin Cooper, Edmund Crelin, Dennis Klatt, Karen Landahl, Bill Laughlin, Alvin Liberman, Molly Mack, or Kenneth Stevens that I valued their thoughts and work. The speech-research groups at Haskins Laboratories, MIT Lincoln Laboratories, and Air Force Cambridge Laboratories and MIT’s Research Laboratory of Electronics have all contributed in some way to this book. Noam Chomsky at the start and Morris Halle were both part of the story, though our paths have since diverged. I can still express my appreciation to my son Daniel Lieberman for his insights on human evolution, John Shea for his reappraisal of the significance of the archaeological record of stone-tool fabrication and use, David Gokhman and his colleagues for their genetic insights on of the evolution of human vocal anatomy, and Robert McCarthy for perfecting the reconstruction of the vocal tracts of extinct hominins.

Sheila Blumstein, Joseph Friedman, Geoffrey Laitman, Angie Morey, Emily Pickett, Joan Sereno, and scores of students at Brown University were colleagues in research. CARTA (Center for Academic Research and Training in Antrthropogeny) meetings over

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the course of the last two decades pointed out both answers and new questions. Marcia Lieberman was my constant companion in research at strange locations in Nepal and the Himalayas, such as Everest Base Camp, Lo Manthang, and Inner Dolpo. She has challenged me in the more than fifty years that we’ve been together and spent days unscrambling my prose. Eric Schwartz, Robert Fellman, and the editorial staff at Columbia University Press did their best.

But the infelicities and errors that you may find are mine.

PRAISE FOR

T H E T H EO RY T H AT C H A N G E D E V E RY T H I N G

“An awesome accompanying book for anyone who reads On the Origin of Species.”

ROB DESALLE, CURATOR OF ENTOMOLOGY AT THE AMERICAN MUSEUM OF NATURAL HISTORY

“Strikes a balance between the historical context in which Darwin made his remarkable contributions to science and contemporary scientific work.”

CHRISTINA BEHME, BRANDON UNIVERSITY

COLUMBIA UNIVERSITY PRESS / NEW YORK cup.columbia.edu Printed in the U.S.A.