Small height evolved twice on 'Hobbit' island of Flores

Small height evolved twice in humans on the Indonesian island of Flores, according to a study.

Researchers from Princeton University in the US created a tool for finding archaic genetic sequences in modern DNA, as no one has been able to recover DNA from the fossils of Homo floresiensis, nicknamed the "hobbit".

They found that a modern pygmy population evolved short stature independently of the extinct 'hobbit' pygmy species that lived on Flores Island, tens of thousands of years earlier.

H floresiensis was significantly smaller than the modern Flores pygmies, standing about 3.5 feet tall, while modern pygmies average about 15 inches taller.

"In your genome - and in mine - there are genes that we inherited from Neanderthals," said Serena Tucci, a postdoctoral research associate at Princeton University.

"We scan the genome and look for chunks that come from different species - Neanderthal, Denisovans, or something unknown," said Tucci.

She used this technique with the genomes of 32 modern pygmies living in a village near the Liang Bua cave on Flores Island, where H floresiensis fossils were discovered in 2004.

"They definitely have a lot of Neanderthal. They have a little bit of Denisovan. We expected that, because we knew there was some migration that went from Oceania to Flores, so there was some shared ancestry of these populations," said Tucci, first author of the study published in the journal Science.

But there were no chromosomal "chunks" of unknown origins, researchers said.

"If there was any chance to know the hobbit genetically from the genomes of extant humans, this would have been it," said Richard Green, an associate professor at the University of California-Santa Cruz (UCSC).

"But we don't see it. There is no indication of gene flow from the hobbit into people living today," Green said.

The researchers did find evolutionary changes associated with diet and short stature.

Height is very heritable, and geneticists have identified many genes with variants linked to taller or shorter stature.

Tucci and her colleagues analysed the Flores pygmy genomes with respect to height-associated genes identified in Europeans, and they found a high frequency of genetic variants associated with short stature.

"It sounds like a boring result, but it's actually quite meaningful," Green said.

"It means that these gene variants were present in a common ancestor of Europeans and the Flores pygmies.

"They became short by selection acting on this standing variation already present in the population, so there's little need for genes from an archaic hominin to explain their small stature," Green said.