Last updated October 25, 2018 at 3:02 pm
A modern group of short-statured people living on the island of Flores are not genetically related to the original ‘hobbits’ Homo floresiensis.
The Liang Bua cave on Flores where H. floresiensis was discovered, and near which a modern population of similarly short-statured people live. Credit: Rosino/Flicke
On the island of Flores in South East Asia, not that far north of Western Australia, populations of tiny humans arose twice, completely independently and separated by tens of thousands of years.
The research by an international team led by Princeton University, and published in Science, found that a modern group of short-statured people living on the island today bear no genetic relation to the “hobbits” Homo floresiensis, who lived on the island until around 54,000 years ago.
Intriguingly, the modern population live close to the cave in which H. floresiensis was found.
Homo floresiensis
The mystery of H. floresiensis, or the hobbits of Flores, began in 2001 with the discovery by a team from UNE of an oddly curved forearm bone. Later, this was followed by the discovery of a skeleton originally thought to be a small child. However, the teeth in the skull weren’t a child’s; they were well-worn, permanent teeth. What they had found instead was the remains of an extremely tiny adult.
“None of the bones looked obviously pathological,” English paleopathologist Professor Alice Roberts wrote of her chance to study the remains.
“The shape of the pelvis and the proportions of the limbs looked primitive – reminiscent of australopithecines, or the earliest of human species, Homo habilis, from around 2-3m years ago.”
Reconstruction of an adult female H. floresiensis (front, center) alongside reconstructions of H. sapiens (left) and H. neanderthalensis (right). Credit: Ismoon, Wikimedia Commons, Musée des Confluences
What the archaeologists from ANU had discovered was in fact a completely new form of archaic human which lived in the area until between 50,000 and 60,000 years ago.
It remains to this day a mystery as to why the “hobbits” were tiny, the discovery of more remains and analysis by experts such as Roberts ruled out disease. Something had lead them to only grow to a maximum height of around 1 metre.
A 2017 study revealed they could not be descendants of Homo erectus, an archaic hominin that emerged from Africa around 2 million years ago and well before Homo sapiens. Instead, they were related to something even more primitive – a close cousin of the Homo habilis that Roberts had thought they resembled.
With a similarly short-statured population living on the island today, and close to the cave where the hobbits were discovered, it had been wondered whether H. floresiensis genes were still present today, leading to their diminutive size.
Modern population unrelated
However, genetic analysis of the modern population of short-statured people living on the island revealed no genetic relation to that original pygmy population.
The researchers collected and analysed the DNA of 32 modern pygmy humans living in the nearby town of Rampasasa, which included 10 whole-genome sequences, and studied their genetic variation.
The genomic analysis revealed a complex genetic history for the modern pygmies, one that contains both Neanderthal and Denisovan ancestry, along with Homo sapiens. However, the authors found no evidence of gene flow with H. floresiensis or other archaic hominins.
The DNA suggested that their ancestors had come to Flores in waves within the last 50,000 years when modern humans reached Micronesia, and again around 5000 years ago from East Asia and New Guinea.
What they found instead was that short-stature phenotype of the modern Flores was developed through natural selection of naturally occurring genetic variation, rather than genetic heritage.
As the modern pygmies of Flores are not the descendants of H. floresiensis, this suggests that the dwarfism which characterises both populations arose twice and in at least two separate hominin lineages.
It’s known that isolation of island life can have strange effects. On Cyprus, hippos shrunk to roughly the size of sea lions. On Flores itself an extinct elephant was no larger than a large pig, but rats became as big as cats. These kind of occurrences are thought to happen when food and predators are scarce, leading to big animals shrinking and small ones growing. It has also been seen in humans, with suggestions evolution also favoured short stature on the Andaman Islands near Thailand and Myanmar.
We can now add Homo floresiensis and the modern population to that mysterious island effect.
