一只作證的蒼蠅

∷王偉濱

不知不覺間，美劇《犯罪現(xiàn)場(chǎng)調(diào)查》CSI（Crime Scene Investigation）連續(xù)播出已有14年時(shí)間，在第十個(gè)年頭上，法醫(yī)昆蟲學(xué)家（forensic entomologist） Gil Grissom終于離開警隊(duì)，去密林深處找尋他的小蟲們了。從那以后，CSI兩次換主演，然而不論專業(yè)知識(shí)還是個(gè)人魅力，新人總難以企及 Grissom。老劇迷們明白，沒有了Grissom和他時(shí)常擺弄的那些盛在瓶瓶罐罐中（學(xué)名叫vials，“玻璃瓶”）的小蟲們，CSI 便失去了靈魂，幾乎只剩下冰冷與血腥，于是，也便離曲終人散不遠(yuǎn)了。

這世界上，不知有多少人因?yàn)镃SI而喜歡上了法醫(yī)這門“學(xué)問”，我也算其中之一吧；當(dāng)然，我只是停留在“喜歡”的層面，實(shí)則是個(gè)門外漢（layman）。不過，這份“喜歡”卻帶著我走進(jìn)哈佛大學(xué)出版社出版于2000年的一本極為有趣的書——A Fly for the Prosecution（起訴）: How Insect Evidence Helps Solve Crimes。這書的主角是一群“讓人尊敬”的小蟲，作者是夏威夷大學(xué)昆蟲學(xué)教授M. Lee Goff，此君從20世紀(jì)80年代開始，便擔(dān)任檀香山警局的法醫(yī)昆蟲學(xué)顧問（Consultant in Forensic Entomology to the Medical Examiner of the City and County of Honolulu），算得上Forensic Entomology方面的權(quán)威人士。CSI 中的Grissom，從學(xué)識(shí)到“俏皮”（甚至Grissom從第四季開始留起的那有型的大胡子）與他都頗為相像；因此，讀此君書，對(duì)于CSI 迷來說，自然有種特殊的親近之感。

雖然由Harvard UP這樣的頂級(jí)學(xué)術(shù)出版機(jī)構(gòu)出版，但A Fly for the Prosecution并非艱深的學(xué)術(shù)著作，盡管各種昆蟲的拉丁文名稱的確令人頭昏腦脹。這其實(shí)是一本頗為“安靜”的書，雖然里面滿是嚇人的小蟲的圖示，就連各篇章的分割線也是由兩條親密的maggots（蛆）組成。說它“安靜”，是因?yàn)?，它?huì)讓你感到一種“超脫生死”的愉悅，更會(huì)給你一種因自然界中“小生命”的偉大和“真誠”而產(chǎn)生的欣喜。

若要涉足Forensic Entomology，首先需要轉(zhuǎn)變對(duì)于死亡的看法——在自然界，萬物都是cycling與recycling過程中的某個(gè)節(jié)點(diǎn)，而“小蟲們”則是這個(gè)過程中的催化劑：

“Anyone involved in death investigations quickly becomes aware of the connection between dead bodies and maggots. Insects are major players in nature’s recycling effort,and in nature a corpse is simply organic matter（有機(jī)物）to be recycled. Left to its own devices（任其自然）, nature quickly populates a corpse with a diverse community of organisms, all dedicated to reducing the body to its basic components. Very quickly, ‘worms’ appear,crawling out of the various orifices（孔口）”。

小小的蛆蟲，千百年來，總被人類認(rèn)為是“討厭”、甚至“可怕”的東西，它們的存在似乎只是證明了生命的脆弱和塵世的骯臟。在Charles Baudelaire（波德萊爾）的Les Fleurs du mal（《惡之花》）中，有一首名為《腐尸》（“A Carcass”）的詩，這樣描寫道：

Recall to mind the sight we saw, my soul,That soft, sweet summer day:

Upon a bed of flints（燧石）a carrion（腐尸）foul（污穢的）,

Just as we turn’d the way,

...

The sky regarded as the carcass proud

Oped（opened古體寫法） flower-like to the day;

The flies the putrid（腐爛的） belly buzz’d about,

Whence black battalions（部隊(duì)）throng（擁擠）

Of maggots, like thick liquid flowing out

The living rags along.

And as a wave they mounted and went down.

Or darted（猛沖）sparkling wide;

As if the body, by a wild breath blown,

Lived as it multiplied.

...

Yet you will be like that corruption too,

Like that infection prove—

Star of my eyes, sun of my nature, you.

My angel and my love!

...

（Translated by Richard Herne Shepherd）

愛人，想想我們?cè)?jīng)見過的東西，

在涼夏的美麗的早晨：

在小路的拐彎處，一具丑陋的腐尸

在鋪石子的床上橫陳

……

天空對(duì)著這壯麗的尸體凝望，

好像一朵開放的花苞

蒼蠅嗡嗡地聚在腐敗的肚子上，

黑壓壓的一大群蛆蟲

從肚子里鉆出來，沿著臭皮囊，

像黏稠的膿一樣流動(dòng)。

這些像潮水般洶涌起伏的蛆子

嘩啦嘩啦地亂撞亂爬，

好像這個(gè)被微風(fēng)吹得膨脹的身體

還在度著繁殖的生涯。

……

可是將來，你也要像這臭貨一樣，

像這令人恐怖的腐尸，

我的眼睛的明星，我的心性的太陽，

你，我的激情，我的天使！

……

（錢春綺 譯）

殘酷的詩人向身邊的愛人宣稱，路邊的腐尸也是美麗的她難以擺脫的歸宿，只有不朽的詩篇可以保存“愛的形姿和神髓”（I have kept the godlike essence and the form / Of perishable bliss!）。

即便是經(jīng)常與小蟲們打交道的法醫(yī)，也往往只是厭惡地把它們沖刷干凈，而沒有意識(shí)到除了把尸體“蹂躪”得一塌糊涂之外，它們還能有什么作用。韓愈在《馬說》開篇感嘆道，“世有伯樂，然后有千里馬。千里馬常有，而伯樂不常有。”世間的一切事物同是這個(gè)道理——這世界上并不缺少有價(jià)值的東西，但缺少有價(jià)值的眼睛。對(duì)于小蟲們來說，forensic entomologist便算得上它們的伯樂了。

有時(shí)，我們不能不感嘆，對(duì)于自然的奧秘，人類所知不僅甚少，而且也是甚晚的。長期以來，人們一直以為蛆蟲是原本存在于人或動(dòng)物體內(nèi)的，在活體死亡之后，便從體內(nèi)鉆出來，吞吃尸體。今天，在中國的某些地方，人們還把臘肉上的“小蟲”，稱作“肉芽”，大概認(rèn)為那些小東西是像豆芽一樣，從肉里鉆出來的呢。在西方，直到1668年，意大利醫(yī)學(xué)家Francesco Redi才通過實(shí)驗(yàn)證實(shí)，蛆蟲與蠅卵（ fly eggs）之間是存在直接聯(lián)系的。

不過，像很多重大科學(xué)發(fā)現(xiàn)一樣，倒是中國人很早便在法醫(yī)昆蟲學(xué)方面有了建樹。據(jù)Lee Goff說，“大宋提刑官”宋慈便是Forensic Entomology的先驅(qū)之一：“In 1235，a Chinese“death investigator”named Sung Ts’u（宋慈）wrote a book entitled The Washing Away of Wrongs（《洗冤集錄》）, which was translated into English by B. E. McKnight in 1981. Sung tells of a murder in a Chinese village in which the victim was repeatedly slashed（砍）. The local magistrate（地方法官） thought the wounds might have been in flicted（造成）by a sickle（鐮刀）. Repeated questioning of witnesses and other avenues（途徑） of investigation proved fruitless. Finally, the magistrate ordered all the village men to assemble（集合）, each with his own sickle. In the hot summer sun, flies were attracted to one sickle, because of the residue（殘留）of blood and small tissue（組織）fragments still clinging to the blade and handle. Confronted with this evidence, the owner of the sickle confessed to the crime. The magistrate’s action demonstrates considerable knowledge of the activity patterns of the flies, which were certainly blow flies（麗蠅）”。此外，有關(guān)昆蟲在斷案中的重要作用，《洗冤集錄》中另有多處提及，足見宋提刑在此領(lǐng)域的洞見。

今天，forensic entomologists與他們信賴的小蟲們對(duì)于探案的最重要貢獻(xiàn)是“確定死亡時(shí)間”（to determine the time since death, the postmortem interval)。此領(lǐng)域的有兩位奠基者——Bernard Greenberg和Jerry Payne。前者關(guān)于多種麗蠅的生物和生命周期（the biology and life cycles）的研究為辨識(shí)小蟲們的“年齡”提供了依據(jù)。而后者提出的“succession”（接續(xù)）理論，則為辨識(shí)小蟲們來到的先后次序指明了道路。“Simply stated, succession is the idea that as each organism or group of organisms feeds on a body, it changes the body. This change in turn makes the body attractive to another group of organisms, which changes the body for the next group, and so on until the body has been reduced to a skeleton. This is a predictable process, with different groups of organisms occupying the decomposing body at different times”。于是，結(jié)合二人的理論，forensic entomologist便可以讓小蟲們說話，判定死亡時(shí)間了。

1996年11月，在夏威夷某地（時(shí)間與地點(diǎn)是識(shí)別小蟲的關(guān)鍵）一片甘蔗地中發(fā)現(xiàn)一具“分解狀態(tài)”的（decomposed，常譯作“腐爛的”，但從尊重小蟲們和死者的角度來看，稱為“分解狀態(tài)的”似乎更合適，因?yàn)樯螒B(tài)本就是compose與decompose兩面）女尸。在分析了于拋尸地采集的各類小蟲后，Lee Goff斷定死亡時(shí)間為樣本(specimen)采集前的34天。據(jù)此，警方鎖定了最后與死者接觸的人，并獲得搜查證（search warrant）；在仔細(xì)搜查了曾經(jīng)嫌犯細(xì)心清理的住所后，警方最終通過luminol(發(fā)光氨)技術(shù)發(fā)現(xiàn)了大量血跡：“When luminol was sprayed（噴灑）in the bedroom and the lights were dimmed（調(diào)暗）, the outline of a body was clearly visible on the floor beside the bed. The body had been lying on its side and blood had seeped（滲出）out of it to form the outline”。顯然，若非小蟲們“作證”，警方便難以鎖定嫌犯，更無法得到搜查證，冤案便不知如何昭雪了。

有時(shí)候，小蟲們提供的線索遠(yuǎn)比“死亡時(shí)間”更有趣。1992年8月27日，在Grand Canyon（大峽谷）的某個(gè)山崖下發(fā)現(xiàn)了一對(duì)男女的遺體，尸體解剖證實(shí)，二人是在一處沙漠地帶溺水死亡（The results of the autopsies indicated that both had died by drowning, even though the bodies had been recovered in a dry, desert area），這結(jié)論當(dāng)然不可思議，除非，你假設(shè)他們是溺水而死后，又被人撈起，然后拋尸他處。然而，Lee Goff分析了現(xiàn)場(chǎng)小蟲的樣本，以及當(dāng)?shù)赝寥罉颖竞?，得出結(jié)論：“It appeared that the two hikers, last seen alive on August 18,had left the marked trail（有標(biāo)志的路線） through the canyon. The woman had fallen, injuring her leg.Her companion then climbed down to assist her and fashioned（制作） the crude（簡陋的） splint(夾板）.Because of injuries or oncoming darkness, they found themselves spending the night of the twenty- first on the canyon floor. During the evening, a flash flood(驟發(fā)山洪）swept through the canyon, drowning them both, and depositing their bodies downstream, 100 feet apart on rocks at the base of a cliff. As is typical in flash floods, the water evaporated quickly（蒸發(fā)）,leaving no trace. With daytime temperatures ranging from 81 to 100 ℉, their clothing quickly dried and insects immediately began to arrive at the bodies.Thus they were discovered five days later, having drowned in a desert”。

與蛆蟲和尸體整日為伍，大概要算得上一份真正意義的“dirty job”了吧。不過正如Lee Goff所說，“As forensic entomology has changed, I also have changed... I am no longer concerned with just the insects and what they do to each other. I have entered into an area where insects, crime, and our criminal justice system intersect with（交叉）very darkest aspects of human nature.” 被Lee Goff親切地稱作“witnesses”（證人）的小蟲們不會(huì)撒謊，不會(huì)爽約，它們總是在該“到場(chǎng)”的時(shí)候“到場(chǎng)”；與這些“可愛”而“單純”的creepy-crawlies（爬蟲）相比，反倒是“人”讓昆蟲學(xué)家難以理解了：在很多的案件中，案發(fā)地附近，甚至當(dāng)場(chǎng)，便有不止一個(gè)目擊“證人”，但是這些人既沒有出面制止犯罪，也沒有站出來在法庭上指證罪犯?！癐 find myself looking again at old questions regarding human nature. Some things I am certain I will never be able to comprehend”。也許，在良知的法庭上，小蟲們也是指證我們的證人吧。