Scientists Understand Why there are Short-statured Indonesians Today, But Can they Explain Hobbit Height?

Michael Westaway  & Francis David Bulbeck / The Conversation

Humans are diverse in size and shape – but some populations are of relatively low average height, and historically described using the term “pygmy”. Some researchers have suggested that the Rampasasa inhabitants of the Flores highlands of Indonesia are one such group.

A paper published in Science looked at whether the Rampasasa are related to an ancient human-like being that was also small in stature and once lived on the island of Flores – the archaic hominin Homo floresiensis, commonly referred to as “the Hobbit”. The Rampasasa live near Liang Bua, where the Hobbit fossils were first discovered.

Rampasasa people are from Waemulu village, Flores – near Liang Bua where ‘the Hobbit’ fossils were discovered. (Dean Falk, Florida State University , Author provided)

The study finds no evidence of a genetic relationship – which isn’t surprising, even though a paper published in 2006 suggested otherwise.

The key claim made by today’s paper is that there have been two independent cases of insular dwarfism (reduction in size over time) evolving on Flores: one in our species Home sapiens, and another that resulted in the emergence of Homo floresiensis.

• A Telling Smile: Tooth Variation Shows Hobbit was Entirely Separate Human Species
• Second Group of Tinier than Hobbit Hominins Found on Flores Island
• Humans Wiped Out the Hobbit: New Study Suggests Homo Sapiens Caused Extinction of Tiny Homo Floresiensis Species

But is this really the case?

Short-Statured Humans

In anthropology, the term “pygmy” refers to populations with an average male stature of less than 150cm and an average female stature of less than 140cm – here we’ll use the term “short-statured”.

There are true short-statured populations to this day in the Andaman Islands (north of Sumatra) and the African rainforests, and borderline peoples in the rainforests of the Malay Peninsula and the Philippines.

1921 photo of African pygmies and a European explorer. (Public Domain)

Across Africa, South Asia and South East Asia, short-statured populations in the past were interpreted as representing a single ancient migration out of Africa of modern humans who all shared a close ancestry.

Even in Australia, it was considered by one anthropologist (Dr Joseph Birdsell) that short-statured Indigenous people living in the closed rainforests behind Cairns were part of this first ancient migration of modern humans.

This hypothesis came undone through a better understanding of the genetic diversity of these populations and improved knowledge of how modern humans adapt to closed forests – including in Australia.

The Stature of the Rampasasa

According to 1940s data collected by enigmatic anthropologist W. Keers, average male stature varied between 154cm and 163cm in the Indonesia’s Flores highlands, central Timor and Sumba. They are short people, yes, but not so-called “pygmies” by classical definition.

The same would apply to the Rampasasa, based on their average stature of 146cm across 35 males and 41 females. Given this is a mixed sex sample, it’s somewhat confusing that the new Science paper refers to the Rampasasa as “pygmies”.

The Rampasasa men have a shorter-stature compared to the scientists (Maciej Henneberg and Robert Eckhardt) in this picture. (Maciej Henneberg and Robert Eckhardt)

Semantics aside, the tiny stature of 110cm for “the Hobbit” Homo floresiensis (female) type is well below the recorded range for modern humans, “pygmy” or otherwise. Various attempts have been made to attribute the tiny stature of “the Hobbit” to diseases such as microcephaly, cretinism, Down sydrome and Laron syndrome.

However these attempts have been unsuccessful in explaining the unique suite of Homo floresiensis characteristics that clearly distinguish it from any modern humans.

Reconstruction of an adult female H. floresiensis (front, center) shown alongside reconstructions of H. sapiens (left) and H. neanderthalensis (right). (Ismoon/CC BY SA 4.0)

The ‘Hobbit’ was Tiny

The existence of “the Hobbit” is based on an original fossil reported at Liang Bua in 2004, and possibly additional evidence located at the earlier site of Mate Menge reported in 2016.

So how could Homo floresiensis have developed its unique features, of which tiny size is just one?

According to archaeological evidence, their ancestors arrived on Flores approximately a million years ago, which allows ample time for evolution through isolation of a species (if we accept the Mate Menge fossil as also being Homo floresiensis) dated to 700,000–60,000 years ago.

The excavation site in Liang Bua, Indonesia where Australian scientists discovered the a female skeleton of an ancient human-like species now referred to as ‘the Hobbit’. (University of New England/AAP)

Some palaeoanthropologists argue that the Hobbit direct ancestor was the Asian hominin Homo erectus, commonly referred to as “Java Man” because it inhabited Java from about 1.7 million years ago until sometime before 100,000 years ago.

Insular dwarfing may explain the tiny size (and remarkably small braincase) of the Hobbit, but it does not easily explain the other features of the skull and lower skeleton that appear more primitive than recorded for Homo erectus.

Replica of Homo Javanensis in Bad Cannstatt, part of Stuttgart, Germany. (Public Domain)

A number of scientists employing phylogenetic techniques that are commonly used across palaeontology propose that a more ancient hominin, perhaps one more closely related to Homo habilis must have reached Flores to give rise to the Hobbit.

Recent archaeological finds in China dated to 2.1 million years ago support the idea that an older, pre-erectus hominin may have been present in Asia.

More fossil evidence is required before we can confidently classify the Hobbit, and establish if it is derived from Homo erectus or whether it represents a so-called “pre-erectus” hominin.

Facial approximation of ‘the Hobbit’ by Dr Susan Hayes. (University of Wollongong/AAP)

Modern Humans in Southeast Asia

Modern humans first moved into the region of Island Southeast Asia as early as 65,000 years ago, heralding the seaborne colonisation of Australia and New Guinea. A later migration of modern humans from Northeast Asia occurred into Island Southeast Asia in the last 4,000 years.

Different physical characteristics in peoples in this region may reflect these two migrations.

The Science paper did find a small genetic contribution to the Rampasasa from two other archaic populations, but this does not distinguish them from other modern humans in the region.

One of these archaic populations is the Neanderthals, whose genetic signature is present in all modern humans outside of Africa. The other is the Denisovans, whose DNA is known only from a finger bone found in a Siberian cave.

Denisovans have been identified as a minor contributor to the DNA of populations today in the Philippines, the islands near Flores, with slightly higher frequencies in the DNA of people from New Guinea and Australia.

The evolution and geographic spread of Denisovans as compared with other groups. (John D. Croft/CC BY SA 3.0)

The genetic data obtained for the Rampasasa are entirely compatible with a dual ancestry as also found for other eastern Indonesians.

• Origins of Indonesian Hobbits Finally Revealed
• Sulawesi Discoveries: Earliest Human Occupation Pushed Back 60,000 Years and Some of the Oldest Cave Paintings in the World
• New Research Asserts that the Hobbits of Indonesia Vanished Earlier than Previously Believed

A Unique Finding Related to Diet

Perhaps the major contribution made by the Science paper is its analysis of a group of genes known as the fatty acid desaturatase (FADS) gene cluster, and how this could modulate dietary related selection pressures.

Where the diet is poor, the FADS gene cluster is shown to select for small stature. This mechanism could be of value in explaining the small stature of some populations (particularly in rainforests and on small islands), as well as other small-bodied individuals in some environments.

The Aeta (Ati) is one of the native peoples of the Philippines. An Ati (Aeta) woman from the hinterlands of Panay Island in the Philippines. (Ken Ilio/CC BY 2.0)

Indeed there may also be an insight here for understanding stature variation in archaic hominins like the Hobbit, if we are able to identify their genomes in ancient fossils or modern human sequences.

Top Image: In this illustration, the modern pygmy village, Rampasasa, is shown at left; in the center, a modern Rampasasa pygmy wearing the traditional head covering and clothing is juxtaposed against the face of a Homo floresiensis reconstruction; at right, pygmy elephants play in the Liang Bua cave where theH. floresiensis fossils were discovered in 2004. Source: Illustration by Matilda Luk, Office of Communications, Princeton University

The article, originally titled We know why short-statured people of Flores became small – but for the extinct ‘Hobbit’ it’s not so clear, by Michael Westaway & Francis David Bulbeck was originally published on The Conversation and has been republished under a Creative Commons license.