How are we related to hobbits?

View similar to that seen from the Liang Bua cave. (Photo by Jose Murillo on Unsplash.com)

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Nowadays, the Liang Bua cave overlooks lush farmland. High above its ceiling, trees blanket the hillside as if they were deliberately trying to hide the island’s violent volcanic beginnings. It’s hard to know what events lead up to her demise, but it’s likely that here, in the shelter of this cave—with a view of the sprawling valley before it—a hobbit took her final breaths of life.

When we think of human history, we often picture a linear progression where primitive beings exist for a time, only to give way as more sophisticated humans develop. And so it goes up to the modern day. This view isn’t necessarily wrong, but it does gloss over some pretty incredible moments in our history—including the evolution of the hobbits.

In 2004, researchers described the discovery of multiple ancient human-like skeletons in the Liang Bua cave, located on the island of Flores in Indonesia [1,2]. The remains belonged to beings who had occupied the cave as recently as 50,000 years ago, with the oldest skeleton among them dating back about 95,000 years [1-3]. But what was truly exceptional about these skeletons was how different they were compared to other ancient human remains in that part of the world—these beings were remarkably small, had disproportionately long arms, and stood on particularly long feet. In other words, they looked like hobbits. Adding to their curious features was the finding that they likely had unusually small brains. Despite having small brains, there is substantial evidence showing that the hobbits had the cognitive competence to make and use tools. Taken together, the short, disproportionate stature and small, but cognitively proficient brains of the hobbits were unexpected and set off a storm of arguments in the scientific community that continues to this day [2,4].

In other words, they looked like hobbits

The argument centers around whether the hobbits of Flores represent ancient humans, or an even older, human-like species. This is important because the answer to this question could potentially rewrite human history.

Currently, it’s believed that around 2 million years ago, the species that came before us (Homo erectus) left Africa and entered the Eurasian continent, marking the first time any human species left Africa. Over time, they spread across the continent and may have contributed to the ancestry of Neanderthals and Denisovans, and therefore to many modern humans today. Groups of Homo erectus that stayed in Africa eventually gave rise to Homo sapiens and modern man [2,5].

One viewpoint argues that a Homo erectus group living in Indonesia approximately 800,000 years ago may have migrated to the island of Flores, where they became isolated from the mainland population. As a result of the unique evolutionary pressures on the island, this group could have evolved into the hobbits. There is substantial evidence supporting this viewpoint, which includes hobbit-like remains located on the island of Flores that are approximately 700,000 years old [2,4,6]. However, Homo erectushad a large brain, causing some to question whether the hobbits could really have evolved from Homo erectus [2].

A competing theory suggest that the hobbits developed from a hominid species that predates Homo erectus. Archeological findings in Africa show us that the predecessors to Homo erectus were smaller in stature and had smaller brains. It is possible—though no evidence currently exists to support it—that these early hominids left Africa and made their way to Indonesia. Once on Flores, their isolation from the mainland population may have preserved their primitive features [2]. If this were the case, it would mean that human-like species left Africa much earlier than we are aware.

Hobbits lived alongside miniature elephants and komodo dragons

Debate over the origins of the hobbits’ features is intense, and fueled partly by the relative scarcity of material for scientists to study [2]. There’s just not that many skeletons and other kinds of material evidence. We do know that they were able to make tools and fire thanks to the discovery of charred bones and ancient, fire-cracked rocks in the Liang Bua cave [2]. We also know that they weren’t alone on the island. Archeological findings tell us that the hobbits lived alongside miniature elephants (Stegodon florensis insularis), gigantic rats, komodo dragons, and a crane-like carnivorous bird that stood six feet tall [7,8]. The presence of these exotic creatures could give us some clues about the hobbits’ origins.

Isolation on an island can lead to dramatic evolutionary change. The elephants of Flores are good examples. In the wake of a cataclysmic volcanic eruption approximately 900,000 years ago, the island became inhabited by new life including Stegodons from nearby islands [7,8]. Large animals may sometimes evolve away from having a large body in the absence of significant predators. Small islands usually have limited resources, so evolution may favor smaller body types that requires less energy. This may be why the Stegodons shrank. Recent modeling suggests that, if Homo erectus did colonize the island, it could have been evolutionarily favorable for them to develop smaller bodies—eventually leading to evolution of the hobbits [4,7,8].

Ultimately, the hobbits’ unique features lead to their designation as a bona fide species, officially called Homo floresiensis. These early humans highlight the branching nature of evolution and remind us that our history is far from being a simple, ordered path from primitive to modern. It will be interesting to see what comes to light in the future as studies continue to explore the origin of these ancient cousins of ours.

References

1. Brown, P., et al. “A New Small-Bodied Hominin from the Late Pleistocene of Flores, Indonesia.” Nature, vol. 431, no. 7012, 2004, pp. 1055–1061., doi:10.1038/nature02999.

2. Aiello, Leslie C. “Five Years of Homo Floresiensis.” American Journal of Physical Anthropology, 2010, doi:10.1002/ajpa.21255.

3. Brumm, Adam, et al. “Age and Context of the Oldest Known Hominin Fossils from Flores.” Nature, vol. 534, no. 7606, 2016, pp. 249–253., doi:10.1038/nature17663.

4. Diniz-Filho, José Alexandre Felizola, and Pasquale Raia. “Island Rule, Quantitative Genetics and Brain–body Size Evolution in Homo Floresiensis.” Proceedings of the Royal Society B: Biological Sciences 284.1857 (2017): 20171065. PMC. Web. 20 Sept. 2018.

5. Michel, Véronique et al. “New Dating Evidence of the Early Presence of Hominins in Southern Europe.” Scientific Reports 7 (2017): 10074. PMC. Web. 21 Sept. 2018.

6. Bergh, Gerrit D. Van Den, et al. “Homo Floresiensis-like Fossils from the Early Middle Pleistocene of Flores.” Nature, vol. 534, no. 7606, 2016, pp. 245–248., doi:10.1038/nature17999.

7. Sutikna, Thomas, et al. “The Spatio-Temporal Distribution of Archaeological and Faunal Finds at Liang Bua (Flores, Indonesia) in Light of the Revised Chronology for Homo Floresiensis.” Journal of Human Evolution, 2018, doi:10.1016/j.jhevol.2018.07.001.

8. Meijer, Hanneke J. M., et al. “The Fellowship of the Hobbit: the Fauna Surrounding Homo Floresiensis.” Journal of Biogeography, vol. 37, no. 6, 2010, pp. 995–1006., doi:10.1111/j.1365-2699.2010.02308.x.