Living on an island can have strange effects. On Cyprus, hippos dwindled to the size of sea lions. On Flores in Indonesia, extinct elephants weighed no more than a large hog, but rats grew as big as cats. All are examples of the so-called island effect, which holds that when food and predators are scarce, big animals shrink and little ones grow. But no one was sure whether the same rule explains the most famous example of dwarfing on Flores, the odd extinct hominin called the hobbit, which lived 60,000 to 100,000 years ago and stood about a meter tall.
Now, genetic evidence from modern pygmies on Flores—who are unrelated to the hobbit—confirms that humans, too, are subject to so-called island dwarfing. On p. 511, an international team reports that Flores pygmies differ from their closest relatives on New Guinea and in East Asia in carrying more gene variants that promote short stature. The genetic differences testify to recent evolution—the island rule at work. And they imply that the same force gave the hobbit its short stature, the authors say.
“Flores is a magical place where things go and get small,” says population geneticist Joshua Akey at Princeton University, a co-author of the study. “This is the only example in the world where insular dwarfism has arisen twice in hominins.”
The pygmies' genomes are also rich in alleles that data from the UK Biobank have linked to short stature. Other East Asians have the same height-reducing alleles, but at much lower frequencies. This suggests natural selection favored existing genes for shortness while the pygmies' ancestors were on Flores. “We can't say for sure that they got shorter on Flores, but what makes this convincing is they're comparing the Flores population to other East Asian populations of similar ancestry,” says population geneticist Iain Mathieson of the University of Pennsylvania.
Source: https://www.science.org/doi/10.1126/science.361.6401.439
Now, genetic evidence from modern pygmies on Flores—who are unrelated to the hobbit—confirms that humans, too, are subject to so-called island dwarfing. On p. 511, an international team reports that Flores pygmies differ from their closest relatives on New Guinea and in East Asia in carrying more gene variants that promote short stature. The genetic differences testify to recent evolution—the island rule at work. And they imply that the same force gave the hobbit its short stature, the authors say.
“Flores is a magical place where things go and get small,” says population geneticist Joshua Akey at Princeton University, a co-author of the study. “This is the only example in the world where insular dwarfism has arisen twice in hominins.”
The pygmies' genomes are also rich in alleles that data from the UK Biobank have linked to short stature. Other East Asians have the same height-reducing alleles, but at much lower frequencies. This suggests natural selection favored existing genes for shortness while the pygmies' ancestors were on Flores. “We can't say for sure that they got shorter on Flores, but what makes this convincing is they're comparing the Flores population to other East Asian populations of similar ancestry,” says population geneticist Iain Mathieson of the University of Pennsylvania.
Source: https://www.science.org/doi/10.1126/science.361.6401.439
