More than 140 sign languages are used today， primarily by deaf communities around the world. Like spoken languages， each sign language has its own grammar， vocabulary and other special features.

For example， American Sign Language and British Sign Language are mutually unintelligible. In fact， American Sign Language has more in common with French Sign Language， largely because French educators were instrumental in helping get deaf schools established in the United States during the 19th century.

But while the lineages and development of spoken languages are well-studied， “There havent been a lot of large-scale comparisons of sign languages，” University of Texas at Austin linguist Justin Power says. He and his colleagues aim to address that information gap.

“In order to study the question of sign language evolution， we first assembled a database of manual alphabets from dozens of different sign languages around the world. A manual alphabet is sort of a subsystem within a sign language that is used to represent a written language. So theres a hand shape that corresponds to each letter.”

當(dāng)今在用的手語超過140種，使用者主要是世界各地的聾啞人。就像口語一樣，每種手語也有自己的語法、詞匯和其他特征。

例如，使用美國手語的人就無法和使用英國手語的人溝通。事實(shí)上，美國手語和法國手語有更多的相似之處，主要是因?yàn)?9世紀(jì)法國教育家對美國聾啞學(xué)校的建設(shè)起到了重要作用。

盡管人們對口語語系和口語演變進(jìn)行了深入的研究，“但是目前對手語的大規(guī)模對比研究還不多?！?得克薩斯大學(xué)奧斯汀分校的語言學(xué)家賈斯汀·鮑爾說。賈斯汀和他的同事想要彌補(bǔ)這一信息缺口。

“為了研究手語的演化過程，我們首先收集了全世界幾十種不同手語的字母表，組建了一個(gè)數(shù)據(jù)庫。手語字母表是手語的一種子系統(tǒng)，用來代表書面語言，也就是說每種手型都會在書面語言中找到對應(yīng)?！?/p>

Powers team chose to study manual alphabets because a record of them exists going back to the late 16th century in Europe. To uncover relationships between the alphabets， the researchers used the same methods that biologists use to trace relationships between different species， based on their DNA.

The methods grouped sign languages in this study into five main European lineages. And those were Austrian origin， British origin， French origin， Spanish origin and Swedish origin.

Power says manual alphabets from Austria， France and Spain could be traced back to one-handed manual alphabets from 16th- and 17th-century Spain. But each of these lineages evolved independently of each other. And the British lineage， which uses a two-handed manual alphabet， eventually made it to Australia， New Zealand and India.

The study also confirmed the French origins of American Sign Language and those of other countries， including Mexico， Brazil and the Netherlands.

Surprisingly， the Austrian manual alphabet influenced sign languages as far away as Russia. But while this lineage has largely died out， remnants of it live on in Icelandic Sign Language today.

The study is in the journal Royal Society Open Science.

Power says future research comparing the vocabularies of different sign languages could provide even more clues about how theyve changed over time.

“Understanding how sign languages evolve would tell us a lot about the way that language， in general， evolves.”

鮑爾的團(tuán)隊(duì)選擇研究手語字母表，是因?yàn)槭终Z字母表的記錄可以追溯到16世紀(jì)晚期的歐洲。為了找到這些字母表之間的關(guān)系，研究人員使用了生物學(xué)家同樣會用到的方法，生物學(xué)家會根據(jù)基因追蹤不同物種之間的關(guān)系。

在這項(xiàng)研究中，研究人員將不同的手語分為五大歐洲語系，分別是奧地利手語、英國手語、法國手語、西班牙手語和瑞典手語。

鮑爾說，奧地利、法國以及西班牙的手語字母表可以追溯到16世紀(jì)和17世紀(jì)的西班牙單手字母表，但是這些語系均獨(dú)立演變，互不相干。而英國手語使用的是雙手字母表，最終傳播到了澳大利亞、新西蘭和印度。

這項(xiàng)研究還證實(shí)了美國手語和其他一些國家（包括墨西哥、巴西和荷蘭）的手語源自法國。

令人驚訝的是，奧地利手語字母表甚至影響了遠(yuǎn)在俄羅斯的手語。雖然奧地利手語幾乎消失殆盡，但在今天的冰島手語中依然能看到奧地利手語的影子。

這項(xiàng)研究發(fā)表在英國《皇家學(xué)會開放科學(xué)》雜志上。

鮑爾說，未來不同手語詞匯的比較研究可能為我們提供更多的線索，讓我們探明手語是如何演變的。

“了解手語的演變規(guī)律，我們就能看出語言的總體演變規(guī)律?！?/p>

Word Study

unintelligible /'?n?n'tel?d??bl/ adj. 難以理解的;難懂的

lineage /'l?ni?d?/ n. 世系;宗系

address /?'dres/ v. 設(shè)法解決;處理

We must address ourselves to the problem of traffic pollution.

assemble /?'sembl/ v. 收集

evolve /i'v?lv/ v. 逐步發(fā)展，逐漸演變

Birds are widely believed to have evolved from dinosaurs.

clue /klu?/ n. 線索，跡象