霍比特人曾經(jīng)是高大的人種，然后

常年生活在島上可能會產(chǎn)生奇怪的影響。在塞浦路斯，河馬體形逐漸縮小到海獅的大小。在印度尼西亞的弗洛雷斯，已絕種的大象骸骨顯示其體重不超過大型的豬，但老鼠與貓一樣大。所有這些都是所謂的“島嶼效應(yīng)”的例子——當(dāng)食物和食肉動物稀缺時(shí)，大型動物會萎縮而小型動物會膨脹。但是沒有人能確定它是否足以解釋弗洛雷斯最著名的現(xiàn)象：在6萬至10萬年前曾經(jīng)生活在島上的人類的一個(gè)分支，身高約1米左右的霍比特人。

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. An international team reports this week in Science 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.

現(xiàn)在，來自弗洛雷斯的現(xiàn)代俾格米人的遺傳證據(jù)——與霍比特人無關(guān)——證實(shí)人類也受到所謂的島嶼矮化的影響。一支國際聯(lián)合科研團(tuán)隊(duì)本周在Science雜志上報(bào)告說，弗洛雷斯俾格米人與他們在新幾內(nèi)亞和東亞的最近支的親戚不同，他們的基因存在著更多的變異細(xì)節(jié)導(dǎo)致身材矮小。遺傳差異表明了晚近的進(jìn)化力量——島嶼效應(yīng)在起作用。作者說，他們傾向于認(rèn)為同樣的力量使霍比特人的身材矮小。

"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."

“弗洛雷斯是一個(gè)神奇的地方，那里的東西都會變得越來越小”，共同作者、普林斯頓大學(xué)的人類遺傳學(xué)家Joshua Akey說 ，“在一座島嶼上出現(xiàn)兩支侏儒化人種，這是世界上已知絕無僅有的一例。”

Princeton postdoc Serena Tucci set out to study the Rampasasa pygmies of Flores, who average just 145 centimeters tall. Famed Indonesian paleoanthropologist Teuku Jacob, now deceased, had controversially proposed that the Rampasasa people inherited some traits from the hobbit, whom he thought was a modern human. To explore the pygmies' ancestry, Tucci and her then-adviser, Ed Green of the University of California (UC), Santa Cruz, traveled to Flores. With the pygmies' permission, they began a "model" collaboration with Indonesian researchers, says molecular biologist and co-author Herawati Sudoyo of the Eijkman Institute for Molecular Biology in Jakarta. Her colleagues gathered spit and blood from 32 people and extracted the DNA. Then, Eijkman researcher Gludhug Purnomo hand-carried samples to Green's lab, where he helped sequence 2.5 million single nucleotide polymorphisms, or alleles, in every individual, plus 10 complete genomes.

普林斯頓博士后Serena Tucci 一直研究著弗洛雷斯的Rampasasa 俾格米人，他們的平均身高只有145厘米?，F(xiàn)已去世的，著名的印度尼西亞古人類學(xué)家Teuku Jacob，曾提出有爭議地觀點(diǎn)，認(rèn)為Rampasasa人繼承了霍比特人的一些特征，他認(rèn)為后者也是現(xiàn)代人的一支。為了探索俾格米的祖先，Tucci和她當(dāng)時(shí)的顧問，加州大學(xué)圣克魯茲分校的Ed Green，前往弗洛雷斯。在雅加達(dá)Eijkman分子生物學(xué)研究所的分子生物學(xué)家和共同作者Herawati Sudoyo的幫助下，經(jīng)過俾格米人的同意，他們開始與印尼的研究人員進(jìn)行合作，收集了當(dāng)?shù)?2位俾格米成員的唾液和血液樣本。然后，Eijkman的研究員Gludhug Purnomo將樣品運(yùn)送到Green的實(shí)驗(yàn)室提取DNA?？茖W(xué)家在那里對每個(gè)個(gè)體的250萬個(gè)單核苷酸多態(tài)性等位基因進(jìn)行測序。

The team found no trace of archaic DNA that could be from the hobbit. Instead, the pygmies were most closely related to other East Asians. The DNA suggested that their ancestors came to Flores in several waves: in the past 50,000 years or so, when modern humans first reached Melanesia; and in the past 5000 years, when settlers came from both East Asia and New Guinea.

該團(tuán)隊(duì)沒有發(fā)現(xiàn)可能來自霍比特人的古老DNA痕跡。相反，俾格米人與其他東亞人關(guān)系最密切。DNA表明他們的祖先通過幾波遷徙來到弗洛雷斯：5萬年前左右，現(xiàn)代人類首次到達(dá)美拉尼西亞;過去的5000年里，定居者來自東亞和新幾內(nèi)亞。

The pygmies' genomes also reflect an environmental shift. They carry an ancient version of a gene that encodes enzymes to break down fatty acids in meat and seafood. It suggests their ancestors underwent a "big shift in diet" after reaching Flores, perhaps eating pygmy elephants or marine foods, says population geneticist Rasmus Nielsen of UC Berkeley, who was not part of the study.

俾格米人的基因組也反映了環(huán)境的變遷。他們攜帶了古老版本的基因，可以編碼特殊的酶來分解肉類和海鮮中的脂肪酸。加州大學(xué)伯克利分校的人口遺傳學(xué)家Rasmus Nielsen 說，這表明他們的祖先在到達(dá)弗洛雷斯之后經(jīng)歷了“飲食習(xí)慣的巨大轉(zhuǎn)變”。

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.

通過與英國生物銀行的數(shù)據(jù)進(jìn)行比較，我們知道俾格米人的基因組中存在多組與身材矮小相關(guān)的等位基因。其他東亞人具有類似基因的頻率要低得多。這表明自然選擇有利于現(xiàn)有的基因。賓夕法尼亞大學(xué)的人類遺傳學(xué)家Iain Mathieson說：“我們不能肯定地說他們來到弗洛雷斯后就變得矮小了，但把他們與其他類似血統(tǒng)的東亞人群進(jìn)行比較，似乎得到了令人信服的結(jié)論。”

The discovery fits with a recent study suggesting evolution also favored short stature in people on the Andaman Islands, Green says. Such selection on islands boosts the theory that the hobbit, too, was once a taller species, who dwindled in height over millennia on Flores.

Green說，這一發(fā)現(xiàn)符合最近的一項(xiàng)研究，那項(xiàng)研究表明，安達(dá)曼群島島民矮小的身材在自然選擇中有利。島嶼上的這一現(xiàn)象支持了這樣的理論：霍比特人曾經(jīng)是更高大的人種，當(dāng)他們在弗洛雷斯生活了數(shù)千年之后，變得更加矮小了。

"If it can happen in hippos, it can happen in humans," Tucci says. "Humans are not as special as we think. This shows we evolve like all other animals."

“如果它可能發(fā)生在河馬中，它也可能發(fā)生在人類身上，”Tucci說，“人類并不像我們想象的那么特別。我們遵循像所有其他動物一樣的進(jìn)化路徑。”