The world's smallest human: Why did Homo floresiensis evolve into a 'hobbit'?

Tuchong Creative

In the movie "Lord of the Rings", there is a race called Hobbits. They are small in stature, with an average height of only 1 meter, but they are agile and have excellent senses, helping humans defeat evil forces. Hobbits are a fictional race, but in the real world, there are indeed people like Hobbits, they are the Flores people. However, they are not "born as Hobbits", but gradually become "Hobbits". Recently, scientists have solved the mystery of why the Flores people became "Hobbits".

In 2003, a scientific research team composed of Australian and Indonesian researchers excavated seven ancient human fossils in a cave on Flores Island in southern Indonesia. One of them was relatively complete. After restoration, scientists found that he was only 1.1 meters tall and had a brain capacity of only about 400 ml. At first, experts thought it was a child's skeleton, but they found that the growth gap in the fossil's skull suture had closed and the deciduous teeth had disappeared, indicating that the owner of the fossil was an adult, and a woman around 20 years old. Only then did the experts realize that they had discovered the legendary dwarfs! At that time, the series of movies "The Lord of the Rings" was popular, so the experts affectionately called it "Hobbit". Later, with the publication of a related research paper in the journal "Nature" in 2004, this petite ancient human race had an official name - Flores Man.

The discovery of Homo floresiensis shocked the world, but it also raised a question: Why did Homo floresiensis become so short?

The stratigraphic information at that time showed that the Flores people lived 190,000 to 50,000 years ago, lived by hunting, used fire and made stone tools, so some people speculated that they were a branch of Homo erectus that walked out of Africa. According to fossils found in various places, the height of Homo erectus was about 1.5-1.8 meters. Why is there such a big difference in height between the ancestors and descendants? Is it a simple genetic mutation or is there another story?

Some people have suggested that the reason why the Flores people were short was because they came to the island due to the drop in sea level during the Ice Age and became shorter and shorter due to food scarcity.

Others have suggested that the reason why Flores people are short is that they may be descendants of Homo habilis or even Australopithecus. It is reasonable that if the ancestors were not tall, the descendants would be short.

Later, archaeologists discovered some fossils of dwarf hominins dating back about 650,000 to 770,000 years at another site on Flores called Matamonge. Their bones shared common features with Javanese and Floresians, early Homo erectus from nearby islands. This discovery directly refuted the claim that Floresians were descendants of Homo habilis or even Australopithecus. However, since the fossils found this time lacked postcranial bones, the origin of Floresians and why they became "hobbits" remains a mystery.

After 2013, researchers discovered another humerus fossil dating back about 700,000 years ago in the Matamonge area. This fossil is only 88 mm long, making it the smallest human limb bone ever discovered. However, research on this fossil has been slow. It was not until August 2024 that the research team published its research results in the journal Nature. The most important discovery was that this limb bone retained the significant features of Homo erectus, proving that the ancestors of Flores people were descendants of Homo erectus. So far, the mystery of the origin of Flores people has been solved.

The mystery was solved because archaeologists were able to "restore" the body shape of the fossil owner through incomplete skeletal fossils.

Based on this fossil, researchers compared the body structure characteristics of the Homo erectus fossils in the database and restored that its owner was only 1.08 meters tall, which is 10 centimeters shorter than the fossil discovered in 2003. It is the smallest ancient human discovered so far.

You may be curious about how these paleontologists can restore the body shape of ancient creatures based on a piece of bone less than ten centimeters in size?

In fact, whether it is paleoanthropologists or paleontologists, the fossils they find during their research are generally incomplete, sometimes even just a few fragments. It is very difficult to directly restore the appearance and body structure of ancient creatures through the discovered bone fragments, so at this time, it is necessary to refer to modern animals that are closely related to ancient creatures for comparison. This is comparative anatomy commonly used in archaeology.

For example, dinosaurs’ “relatives” are crocodiles, so the size and body structure of many dinosaurs are inferred and restored based on the skeletal characteristics of crocodiles.

Archaeologists can also infer the size and distribution of muscles through muscle attachment points (traces of muscles remaining on bones), thereby restoring the body shape of ancient organisms.

In some cases, archaeologists can also infer the body size of ancient creatures through the footprint fossils or skin impressions left by them. The size and distribution of the footprints can reflect the weight, gait and body size of the creature.

In addition, archaeologists can also indirectly infer the body size of ancient creatures by studying the ecological environment of the time when the ancient creatures lived. For example, in open grasslands or colder climates, animals tend to be larger to retain heat.

By restoring their body shape, archaeologists have solved the mystery of the origin of the Flores people. So when and why did they become "hobbits"?

The researchers solved the mystery by studying stone tools dating back 1.02 million years, and inferring the time when the Flores people became smaller.

About 1 million years ago, a branch of Asian Homo erectus crossed the strait and came to many islands including Flores. Due to the influence of the environment, their body size underwent island dwarfism, that is, large animals became smaller on the island. For example, the Flores saber-toothed elephant unearthed around the site where the Flores man was discovered was only about 1.5 meters in size. The equally short Luzon Man discovered on Luzon Island in the Philippines in 2019 also proved that the island dwarfism of the Flores Man is not an isolated case.

Due to lack of food, this group of ancient humans became smaller and smaller, and their brains, which consume a lot of energy, also became smaller, even lower than the level of some apes. Judging from the stone tools found on the island, their intelligence level did not make significant progress. Therefore, researchers believe that the rapid shrinkage of these primitive human types on Flores Island reveals the various paths that human evolution may take, and that it is not inevitable that humans become smarter.

Of course, these changes also laid the hidden danger for the extinction of the Flores people. About 70,000 years ago, the Toba volcano in northern Sumatra, Indonesia, erupted. The volcanic ash that covered the sky and the sun caused great damage to the environment. The Flores people were unable to cope with the brain degeneration, which led to the extinction of a large number of their race.

Tens of thousands of years later, modern humans’ ancestors, Homo sapiens, arrived on Flores Island on rafts. As they did on other continents, Homo sapiens, who were good at killing, immediately began to hunt animals on the island, most likely including the short-statured Homo floresiensis. However, due to the very limited archaeological dating materials, it is not certain that it was the last batch of Homo floresiensis, so it is still impossible to accurately know when Homo floresiensis disappeared. Our ancestors, Homo sapiens, are still the number one suspect who killed Homo floresiensis.

Today, the legend of the dwarfs is still circulating among the people of Flores. According to the legend, the dwarfs have hair on their bodies, can walk upright, and even speak some simple human language. If this is true, then the Flores people may have lived hundreds of years ago, but this requires more archaeological evidence to prove it.

This article is a work supported by the Science Popularization China Creation Cultivation Program. Author: Liu Sen

Auditor: Gao Yuan Auditor Associate Research Curator, National Museum of Natural History

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.