A 700,000 year old arm bone found on an Indonesian island throws light on the evolution of the Homo Floresiensis 1– an ancient relative of modern humans, nicknamed Hobbit due to his small size.

The arm bone fragment of only 88 millimeters in length was one of the smallest adult adult hominids. The discovery, published on August 6th inNature Communications, supports the idea that the ancestors ofH. floresiensisJust a few thousand years after their arrival on the remote island of Flores in what is Indonesia today, developed into a much smaller way.

Island dwarfism – the process by which animals develop smaller body size through isolation on an island – has occurred frequently during evolution. But before that Discovery ofH. floresiensis, which was reported in 2004 2,, 3, no one thought it could happen to humans,” says study co-author Yousuke Kaifu, an anthropologist at the University of Tokyo.

The assumption that the ancestors ofH. FloresiensisThe fact that they could have developed dwarfism so quickly after arriving on the island is “surprising but also exciting,” he adds.

Island effect

Species that are trapped on an island often go through massive changes to adapt to their new environment. Mammuts, deer and other animals that have landed on islands have all shrunk - possibly because less food is available or because there are fewer threats from predators, says Kaifu.

Scientists suspect that something similar happened with the ancestors ofH. Floresiensiscould have happened. A working…

Ein Bild des Humerusfragments von Mata Menge neben dem Humerus von Homo floresiensis aus Liang Bua, als Maßstab

A breakthrough came in 2015 when the team reconstructed fragmented bones in the lab and found that some broken pieces belonged to a humerus - the bone that connects the shoulder to the elbow. Although the fossil was missing both end pieces, it could still provide some clues about the size of the ancient human to whom it belonged.

Adult bones

The size of the humerus suggested that its owner was tiny - but it could also have belonged to a child rather than an adult. In the latest study, Kaifu and his team examined a piece of the bone under a microscope to investigate this possibility. The structure of the bone suggested that it belonged to a fully grown adult.

The arm bone is 9-16% smaller and thinner than those 60,000 years oldH. Floresiensis-Sexemplar belonged, which confirmed that his owner was "at least as small as later members of the species", says Baab. The researchers estimate that this person would not have been more than 108 centimeters tall.

The results suggest thatH. Floresiensisevolved into a shorter species within 300,000 years after the species' ancestors arrived on the island. Brain findings fromH. floresiensis suggest that your brains have also shrunk during this time. The quick appearance of a new body type shows the many ways that human evolution can take, says Kaifu. "We believe that it was the fate of people to become wise," he says. "Flores shows us that there are other opportunities for people."