23

On Tuesday morning, I wrote on the briefing board: “#SkullDay.” I had seen the skull in the original photos. It appeared as a faint circular outline of white material shining in contrast with the brown cave floor. Most of the bones we could see in the original photos seemed to be lying loose upon the surface, but the skull was embedded in the soil of the cave floor. The previous day’s finds of multiple skeletons in the cave had surprised us. Now we all wondered: What could lie beneath the surface?

By that time, we had seen enough of the fragile condition of the bone coming out of the cave to know that skull removal would be a delicate operation. We decided to work three team members at a time in the Chamber. One team member would scan and collect from the surface while the two others would slowly work around the skull with paintbrushes, gently removing teaspoons of sediment to be bagged and sent up to the Science Tent. Here scientists and students would work through it again with brushes, looking for tiny fragments of bone. I had decided as part of the protocol we would keep every ounce of sediment from the excavation—a procedure that later proved invaluable.

After an hour, the team had cleared enough sediment to show that the skull was not alone. It rested atop of a tangle of long bones. For another two hours we watched the excavation on the video monitors. Gradually, bit by bit, the edges of each bone came into view as team members patiently continued their work.

A big storm was brewing on the eastern horizon, and I called down on the intercom to pull out the team. With the potential of lightning, we needed to shut down all the sensitive electronics on the surface. The team started up right away.

The storm hit before they could get up, and it was a doozy. The region around the Cradle of Humankind has one of the highest lightning strike rates in the world, and it seemed like it was trying to prove that statistic to us with this storm alone. With people running frantically about, trying to secure guide wires and wildly flapping tent flaps, I spent my time trying to keep the Command Center from blowing away, while still keeping an eye on the screens and watching the progress of the scientists and cavers coming out of the cave. Once I saw they had reached the Ladder, I instructed Ashley to shut down the systems and I raced down to the Science Tent to see if I could help secure things. Entering the tent amid loud crashes of thunder, I found John Hawks literally holding the large tent down by bracing the center pole. I cringed: He was effectively embracing a lightning rod.

“That’s probably a bad idea!” I shouted out above the storm.

John’s eyes went wide, and he let go quickly. That was dedication to saving fossils, for sure!

THE STORM PASSED AS quickly as it had arrived, with no serious damage left behind. That evening the more senior scientists sat with the underground astronauts to hear about the excavation of the skull.

“It’s a puzzle box,” Elen told us. “You know that toy where you have to remove one little piece at a time, all in exactly the right order, and you can’t tell them apart? That’s what this is. A puzzle box.” It was a good description of the complex network of bones that surrounded the skull. Every brushstroke revealed another bone. The floor, it seemed, was literally composed of bones—and so far they all were hominin.

Day two moved on to day three as the underground astronauts, runners, Chute Trolls, and safety cavers smoothly rotated through the Chamber in shifts of four or five hours. The recovery of the skull was taking more time than I had planned because of the complexity of the Puzzle Box, as we now called it. Whenever an excavator uncovered a new piece of long bone beneath the skull, she had to follow its length to figure out how it lay and where it ended. Often the fragment lay under yet another bone. Slowly, painstakingly, the work moved outward one teaspoonful at a time. What started as a small excavation radius just around the skull kept growing until it was an area nearly 18 inches across. All along, the team was collecting more and more bones from this little plot.

Meanwhile, team members aboveground in the Science Tent had developed a routine for preparing and cataloging the fossils and storing them in our on-site safe. I spent most of my time monitoring the video cameras and giving advice to the excavators when they called up with questions. Our carefully planned systems seemed to be working.

Something was bothering me, though. Other than those few bird bones, not a single bit of fauna had come up from the Chamber. At first it had occurred to me that in their enthusiasm to find hominin fossils, the six excavators might have been collecting those first and leaving other animal bones in place. But now we had dozens and dozens of individual fossils. If they were indeed leaving other types of bones behind, they needed to start bringing everything up.

At the end of her afternoon shift, I pulled Marina aside. She was tired and dirty, but she was clearly enjoying herself. After asking her some general questions, I got around to what had been bothering me. “Are all of you cherry-picking only hominin remains?”

“No,” she said, surprised at my question. “That’s all there is.”

THAT EVENING I ASKED Peter, Steve, and John to drive down the road with me to a local pub. As we sat down with a cold one, I voiced what I suspected all of us were thinking.

“What the hell are we dealing with here?” I asked them. “I’ve never seen anything like this. That Chamber is full of only hominin bodies.”

“I don’t understand it. Where are the fauna?” Peter agreed, shaking his head as he took a sip of beer.

“Look,” John said, “the bones are not chewed. We’ve got a good number of hand and foot bones, complete, and that’s funny too. We don’t seem to be missing body parts.”

“And I haven’t seen any carnivore damage,” Steve added. Peter nodded in agreement.

The lack of any signs of carnivore damage was striking. Predators and scavengers play a role in accumulating bones at most cave sites. The bones collected by these animals are leftovers of meals, and they have bite and chew marks, signatures of the culprit that created the assemblage. These fossils had none of those signs.

We all looked at each other, thinking the same thing.

Though the four of us had different backgrounds, we each had significant experience working at archaeological or paleontological excavations. At some point we had all worked around human burials; we had all been broadly trained in forensics. We knew that, typically, in South African cave sites the vast majority of what we find are nonhuman animals. Carnivores of many varieties, antelopes, other animals like giraffes or zebras, even rodents, birds, and lizards—we call them all fauna. In almost every fossil situation, fauna represent the vast majority of any bone assemblage.

Hominin fossils, on the other hand, are extremely rare. Roughly tens of thousands, if not hundreds of thousands, of faunal remains are found for every single hominin fossil. This situation is the same in the Rift Valley of East Africa, and in practically every other natural collection situation in the world. Malapa had been an exceptionally rich hominin site, but still the fauna vastly outnumbered the hominin skeletons.

Beyond that, fossil groupings of a single species of animals—what we call a monospecific assemblage—are extraordinarily rare in the fossil record. Usually, when a monospecific assemblage is found, it is the scene of some easily identifiable catastrophic event, like a flood or mass kill site. But even these situations usually include some other species of animals. When a natural catchment traps animals, it usually traps other things too. If a herd of wildebeests drowned in a river, for example, a paleontologist will also find fish fossils, crocodile teeth, and bits of bone that would normally be in the gravel of a river. Maybe even some zebras amid the herd.

One animal is an exception to this rule, and that’s modern humans. Humans are commonly found as monospecific assemblages because we collect our dead and place them together deliberately, keeping them away from other animals. It’s a completely unnatural behavior for other animal species, but it’s a defining character of many human cultures: deliberate body disposal.

This site was getting stranger and stranger.