Detouring past the conference center, I parked in front of the old tourist trap, paid the $1 admission and followed a path of stenciled yellow footprints to a building out back. Inside a cinder-block coffin lay the subject of my quest, what appeared to be the mummified remains of a woman holding a mummified child.

“The Thing” looked human, or maybe like pieces of human dolled up with papier-mâché. Either way, it seemed like a fitting symbol for the complaints I’d been hearing about Dr. Diamond: that through the wide-angle lenses of his books, people appear not as thinking agents motivated by dreams and desires, ideas and ideologies, but as pawns of their environment. As things.

The backlash had been brewing since a symposium last year, “Exploring Scholarly and Best-Selling Accounts of Social Collapse and Colonial Encounters,” at a meeting of the American Anthropological Association in San Jose, Calif. Although “Guns, Germs and Steel” has been celebrated as an antidote to racism  Western civilization prevails not because of inherent superiority, but geographical luck  some anthropologists saw it as excusing the excesses of the conquerors. If it wasn’t their genes that made them do it, it was their geography.

Image Hutu refugees in 1996 on their way back to Rwanda from Zaire. Credit... Peter Andrews/Reuters

“Diamond in effect argues that no one is to blame,” said Deborah B. Gewertz, an anthropologist at Amherst College. “The haves are not to be blamed for the condition of the have-nots.”

Dr. Diamond anticipated this kind of reaction. In the epilogue to “Guns, Germs and Steel,” he acknowledged that human will was an important pivot in the turning of history, as were freak accidents and chaotic “butterfly effects,” in which tiny perturbations are amplified into cataclysms. But the accidents of geography  the availability of raw materials and crops, a hospitable climate, accessible trade routes and even the cartographical shapes of continents  step forth as prime movers.

While “Guns, Germs, and Steel” explored the factors contributing to a society’s rise, “Collapse” tried to account for the downfalls. Here, human agency played a more prominent role. In case after case, Dr. Diamond described how a confluence of factors  fragile ecosystems, climatic change, hostile neighbors and, ultimately, bad decision making  cornered a society into inadvertently damaging or even destroying itself.