Homo floresiensis is a distant cousin of ours who inhabited the island of Flores, Indonesia, until about 50 thousand years ago. Among experts they are also known by the informal nickname of “hobbit”, because they did not measure more than one meter in height even as adults, less than any other known hominid species, including chimpanzees and gorillas. There are still various hypotheses regarding their origin, while regarding their disappearance things are starting to become clearer. In fact, a new study indicates that what caused their decline, together with that of their chosen prey, the small pygmy elephants known as stegodonts, could have been a well-known enemy today: climate change.
Indonesian hobbits
Until some time ago, in fact, it was believed that the hobbits of Flores had survived much longer, up to around 12 thousand years ago. And that a period of high volcanic activity in the region, and growing competition with a much more fearsome species: ours, had contributed to their extinction, in variable percentages.
Recently, however, various studies have dated the disappearance of Homo Floresiensis with more precision, moving the date back by approximately 38 thousand years, and thus removing credibility from previous theories: in that period, in fact, there are no traces of eruptions or conflicts with the ‘homo sapiens that can explain the sudden extinction of these ancient Indonesian pygmies.
For this reason, a team of researchers from the University of Wollongong, Australia, decided to explore another possibility: that climate change played a preponderant role in their demise; credible hypothesis because the island of Flores, the only known habitat of these hominids, owes almost all of its annual rainfall to the summer monsoons, and even small changes in their regularity can therefore have dramatic consequences for its island ecosystem.
To confirm their suspicion, the researchers collected samples in a cave not far from the one where the Homo floresiensis remains were found, and studied the ratio between magnesium and potassium and the relative abundance of different oxygen isotopes in inside the rocks dating back to the period of the disappearance of the small pygmy people. With this information they were then able to reconstruct the rainfall trend, obtaining the confirmation they were looking for: between 76 and 55 thousand years ago the amount of annual rainfall on the island was in fact reduced by 38 percent, creating an environment which at the time of extinction of Homo floresiensis was 51 percent drier than today.
In such an environment, the stogodonts on which the diet of small hominids was based would no longer be able to survive. Without prey, Indonesian hobbits were probably forced to migrate out of their natural environment, reaching the coasts where they could easily have come into contact with Homo sapiens, thus receiving the final blow. This is not a certainty, because the study has not yet been published in a scientific journal, and because more solid evidence will be needed to consider the mystery of the disappearance of Homo floresiensis solved. But the conclusions of the research are plausible, and show us a further example of how dangerous climate changes can be: after having taken thousands of years to adapt to their island environment, reducing their size to a fraction of those of their ancestors, both the stegodonts and Homo floresiensis probably didn’t stand a chance in the face of the very rapid decline of the island’s water reserves.