“This is what Homo floresiensis must have felt like,” a paleoanthropologist mused through the darkness. It is almost 8pm on a Thursday and I am sitting on the floor of the cave known as Liang Bua. Other researchers stand only a meter from me, but I cannot see them, my eyes have yet to adjust to the blackness of the cave that was once home of the tiny hominins known as the hobbits.
About an hour before, the sun had dipped behind the mountains of western Flores, cloaking the Liang Bua Valley in night. This is the first time I have been here at this hour; we generally end our excavation days by 5pm. On this particular day, however, we have extended the day into the night because a team of geologists need sediment samples that can only be collected in the darkness, samples that will be used for optically stimulated luminescence dating (OSL).
OSL is a fascinating dating technique. It examines the mineral grains in sediment (like cave dirt), estimating how long ago they were exposed to sunlight–therefore gauging how long ago they were buried. OSL especially useful when radiocarbon dating is not possible. For example, if the thing that needs to be dated is thought to be beyond the radiocarbon age limit or is not made of material necessary for carbon dating (like bone).
At Liang Bua, OSL dating has the potential to answer some of the questions that remain concerning the timing of modern humans’ arrival at the site–as well as the hobbits’ extinction. The tricky thing about the minerals used in OSL dating, though, is that they reset their clock every time they are exposed to sunlight–or any light at all for that matter. Therefore, the samples must be collected in complete darkness.
This need for nighttime samples meant that a group of us hung around the cave today, catching up on work and waiting for the sun to go down. After a dinner of extra spicy beef rendang (a dish served with chilis and rice), we extinguished the few scattered lightbulbs and introduced an all-consuming darkness. Now, the geologists can work.
The scientists switch on their small, red headlamps (which won’t disrupt the minerals) and set out in the excavation pits. They hammer away while the rest of us wait for our eyes to adjust. Even the light of a phone can alter the samples, so we just sit. In true Liang Bua fashion, an entire team is here to support the four collectors. This place is truly characterized by teamwork.
The geologists take samples from many layers of dirt, in order to get a more clear picture of when each layer was laid down at Liang Bua. Although such layering (stratigraphy) is important at any site, it is especially a concern at here–given that the stratigraphy around the hobbit was originally misinterpreted, leading to estimate that floresiensis lived as recently as 12,000 years ago (we now know they disappeared from Liang Bua about 50,000 years ago).
Deciphering cave layers can be quite tricky. Indeed, in the nineteenth century, many scientists dismissed early Neanderthal fossils because the fossils came from caves. These scientists argued that cave stratigraphy was too misleading, so they distrusted any claims of ancientness from such layers. Liang Bua is no exception. Every time the nearby river flooded, or a volcano erupted, or part of the ceiling collapsed, the cave floor changed, creating a complex series of intricate layers that are tricky to disentangle and differ in every corner of the cave.
As the geologists hammer away in the excavation pits on this particular night, my gaze shifts outside the cave to the surrounding hillside. Outside the cave’s gaping mouth, banana trees and palm trees are illuminated by the nearly full moon. I try to imagine what evenings at Liang Bua would have felt like for the tiny floresiensis hominins, 70,000 years ago.
Nighttime would have truly been terrifying for Homo floresiensis. Even by day, formidable Komodo Dragons roamed the island and giant carnivorous birds like vultures stalked around, searching for meat. It’s difficult to even imagine what sort of dangers these small creatures faced in the dark. My surroundings tonight are much tamer, the only hazard being the attack of fire ants, which causes an occasional shriek and a relocation of our sitting positions. In the hobbit’s version of this world, the darkness must have felt incredibly ominous. We know these tiny hominins couldn’t run very fast, and it seems unlikely that they had consistent control of fire.
One thing that my evening has in common with the nights of the hobbits’ time is the giant rats that are endemic to Flores, creatures that come out at night. I don’t see any tonight–we are far too noisy for them to venture out of their hiding places–but I know they are there. My suspicion has been confirmed by a series of night-hunts the local villagers have conducted this week, hunts that resulted in numerous specimens of this tikus besar (giant rat in Indonesian). These rats, about the size of a Jack Russell terrier, were here when the hobbits were around as well–truly a persistent group of creatures. While the hominins inhabiting Liang Bua have come and gone, the giant rats have remained.
Though I often write about miraculous discovery and fierce controversy on my blog, tonight’s endeavor paints a much more honest picture of science. Science as a process of meticulous measuring, sample collecting, and extensive note taking. The results from tonight’s endeavor, for example, could provide answers to big questions about the disappearance of Homo floresiensis and the arrival of humans in Indonesia. In order to get those answers, however, samples need to be carefully obtained, labeled, analyzed and reanalyzed. Any team fortunate enough to experience occasional flashes of discovery can tell you these flashes interrupt months or years of long days and nights of such tasks.
The sampling continues as the moon climbs high in the sky, illuminating the rice paddies outside. The geologists complete their task around 11pm, collecting the last of the samples and safely wrapping them to ensure they remain in darkness. By now, much of the support team has fallen asleep (Indonesia is a country that tends to rise incredibly early–and go to sleep equally early, a schedule after my own heart). Everyone is woken up, the generator switched on to break the darkness, and we all pitch in to help clean up. Then, we sleepily pile into the trucks and head back to base camp, having briefly obtained a glimpse of what the hobbits felt like at night.