Some interesting science about the evolution of bones.

Wall Street Journal book review.

‘Skeleton Keys’ Review: How to Grow a Spine

An adult human body contains at least 206 bones. Human hands are more dexterous than those of great apes, our shoulders better for throwing. But our ice-age forebears had stouter skeletons than we do, thanks to their strenuous lifestyles.

By John J. Ross
March 1, 2019 9:27 a.m. ET

Pity poor Richard , who snatched defeat from the jaws of victory and met a most grisly end. Even though his army outnumbered that of Henry Tudor at the Battle of Bosworth Field, he led a reckless cavalry charge in the hope of personally finishing off the future Henry VII. Unfortunately, his white courser got stuck in the mud, and he found himself surrounded by a swarm of formidably armed Welshmen.

What happened next was revealed when a battered skeleton was unearthed in 2012 from an unmarked grave under an English parking lot, where the church in which Richard was buried had once stood. Researchers matched the skeleton’s mitochondrial DNA, which is inherited from one’s mother, to that of Richard III’s living maternal relatives.

SKELETON KEYS
By Brian Switek
Riverhead, 276 pages, $26

In Shakespeare’s version of history, Richard was a misshapen sociopath, a “poisonous bunchback’d toad.” Richard’s skeleton showed scoliosis, or a sideways curve in the spine, but nothing that couldn’t be concealed with a bespoke suit of medieval armor. Tudor propagandists, seeking to bolster Henry’s sketchy claim to the throne, had exaggerated Richard’s physical deformities, and perhaps his moral ones as well.

But according to Brian Switek, the author of “Skeleton Keys,” a provocative and entertaining magical mineral tour through the life and afterlife of bone, “the strangest thing about Richard III’s skeleton wasn’t his unceremonious burial or his contorted back. It was what had been done to him on the battlefield.”

Richard’s bones indicated that he died in a flurry of savage violence. There were slashes on his lower jaw and stab wounds in the upper jaw and back. Chunks of scalp and bone had been sliced cleanly off his skull. The crown of his head had been punctured by a dagger plunged in at an odd angle, perhaps as the maimed king was dazed and reeling. Two gaping wounds in the back of the skull may have been made with a halberd as Richard was on his knees. Lastly, there was a gratuitous gash in his pelvis, apparently from a sword thrust after his armor had been stripped away. As Mr. Switek observes: “We are a cruel species, and the marks of our depravity are etched onto Richard’s bones.”

Mr. Switek takes us back to the ancient oceans of 530 million years ago, before the evolution of bone, when the animal kingdom was a blobby throng of “living pincushions, nozzle-nosed foragers, boomerang-headed arthropods, or shutter-mouthed monstrosities.” Skeletons became possible when the weathering of the continents and undersea volcanic eruptions dumped vast amounts of calcium and phosphorus, the raw materials of bone, into the primordial waters. Creatures like our distant relative Pikaia emerged. A primitive mashup of worm, eel and slug, Pikaia had a linear wisp running along its backside. This was a notochord, more the idea of a backbone than an actual backbone. From these humble beginnings would come the whale and the wombat, the turtledove and the Tyrannosaurus. And, of course, us.

The development of true bone about 455 million years ago kicked off an evolutionary arms race. Bones were originally protective plates that grew on the outside, leading to oddities such as the antiarchi, “armored fish that looked like Roombas with tails sticking out the back.” Bone also made possible the evolution of jaws, which took predation to a new level and helped fish move water through their gills. Plus, as Mr. Switek notes, “had these hinges never originated, Peter Benchley’s novel Jaws would have to be renamed something like Pharyngeal Slit or simply Hole, which doesn’t have the same effect.”

Fifty million years later, the bony plates had sunk beneath the flesh to form the skeleton, and a glitch in DNA duplication led to fish with two paired fins and not just one. With all four limbs in place, Mr. Switek writes, “the standard elements of the vertebrate body plan were already set.” By 375 million years ago, fishes able to spend time on land, or “fishapods,” had crawled out of the sea.

The insects and other arthropods had beaten the fishapods onto dry land by tens of millions of years. But the interior bones of fishapods and of their amphibian and reptile descendants allowed them to outgrow their exoskeletal cousins. “Starship Troopers” aside, it is thankfully impossible for insects to attain man-eating stature. As Mr. Switek reassures us: “Keeping all those guts in, rather than supporting them from the inside, becomes ever-more difficult with increasing size. . . . A weevil the size of a VW Bug would immediately burst at its seams.”

The intact adult human body contains 206 bones, sometimes more. Wormian bones, also known as Inca bones because of their high frequency in Andean mummies, are “extra scoops of bone that form around some of the sutures of the skull.” One in 500 people has a cervical rib, which may be a literal pain in the neck, impinging on nerves and impairing blood flow to the arm. And many of us have extra sesamoids, sesame seed–like bones embedded in the tendons of our fingers and toes that improve the leverage of our muscles.

As Mr. Switek writes, “the way we move, the way we live, is bounded by our bones.” Compared with our closest relatives, the great apes, our hands are more dexterous and our shoulders better for throwing and therefore hunting. Our feet are framed for running rather than grasping at branches, and our spines allow us to bear the burden of being upright. But from an evolutionary perspective, we remain a work in progress. We walk on two feet and throw overhand, but not so well as to avoid developing herniated disks and frayed rotator cuffs as we age.

Bone is a dynamic tissue, broken down and built up again throughout life. Stress, in the form of regular exercise, is good for it. Our ice-age forebears had stouter bones than we do, thanks to their strenuous lifestyles. Astronauts lose as much as 20% of their skeletal mass in six months in orbit. Mr. Switek suggests that NASA scientists might be able to manipulate astronaut bones with biomolecules borrowed from hibernating bears. “A bear bones approach may allow researchers to overcome the osteological issues of space travel.” (Mr. Switek has a weakness for dad jokes and sci-fi movie references.)

The malleability of bone has led to creative, if not bizarre, efforts to modify it. The skull was a particular target. In many cultures, flattened or elongated heads were a marker of elite status. In the Americas, the Maya and the Choctaw flattened the heads of their infants. The Huns were a marauding horde of coneheads on horseback. Up until the 20th century, peasant women in the south of France wrapped padded kerchiefs tightly around their babies’ heads for protection, unintentionally stretching them in the process.

This cranial manipulation didn’t impair intelligence and seems to have been harmless, unlike the crippling foot binding practiced on girls in imperial China. The infamous whalebone corsets of the Victorian era flattened spines and deformed ribs, but recent research shows that the effects on life span were probably negligible.

“Skeleton Keys” turns in its final chapters to purloined human remains and the long and lamentable history of their misuse by anatomists, purveyors of racist theories, and crafters who upcycled them into drinking cups and musical instruments. Today the internet has made possible a smartphone-driven market for skulls as morbid objets d’art. The above-ground trade in human bones seems to be as robust as ever, a development deplored by Mr. Switek: “I wouldn’t mind winding up as a skeleton in a museum cabinet after I die, teaching even after death, but the thought of being bought and sold as a decoration, appraised to a certain value, winnowed down to nothing more than an object of curiosity gathering dust, makes my living flesh crawl.”

—Mr. Ross, a physician, is the author of “Shakespeare’s Tremor and Orwell’s Cough.”