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“灭绝物种动物园”有望成真

更新时间:2018-4-16 20:07:36 来源:纽约时报中文网 作者:佚名

The increasingly realistic prospect of 'extinct animal' zoos
“灭绝物种动物园”有望成真

A traveller marvelling at snow leopards in a conservation park. A foodie who wants to taste pangolins without breaking the law. A game hunter tracking a black rhino which will be replenished after the kill.

一位旅行者在一个自然保护公园中惊叹于雪豹的雄姿。一位美食家想在不违法的情况下品尝穿山甲的美味。一个猎人正在追杀黑犀牛,猎杀之后黑犀牛即可得到重新补给。

To some people, these scenarios seem like dystopian nightmares. To others, they’re exciting prospects. And as the science advances, they may be more feasible than they might first appear. Some researchers are even exploring how animal cloning could change the tourism industry by 2070.

对某些人来说,这些场景似乎是明日世界的噩梦。对另一些人,则是令人兴奋的克隆动物产业前景。随着科学的进步,这些场景变成现实或许指日可待。研究人员甚至正在探索如何在2070年前通过动物克隆改变旅游业。

State of the art

前言研究

A Jurassic Park situation of dinosaurs once more roaming the Earth remains a fantasy. De-extinction is incredibly challenging and it’s not clear whether dinosaur DNA even can be recovered. With current technology, DNA samples only remain useful for about 1 million years – so theoretically we could clone a Neanderthal, but not a Triceratops last seen 65 million years ago.

《侏罗纪公园》中的恐龙再次漫步地球仍只是一种幻想。复活灭绝物种极具挑战性,况且恐龙的DNA能否被复原都是一大问题。根据目前的技术,DNA样本的有效期大概仅有100万年——所以理论上我们可以克隆出一个尼安德特人(穴居人),而没法克隆出存活于6500万年前的三角恐龙。

Woolly mammoth DNA is more accessible. We have flash-frozen mammoth samples and can implant the genetic material into elephants, which are genetically similar. We can’t actually bring mammoths back in habitats resembling their original ones, though, where they could breed naturally.

猛犸象的DNA则更易获得。我们有快速冻结的猛犸象样本,可以将遗传物质植入与其基因相似的大象体内。实际上,我们无法在其原始栖息地类似环境中将猛犸象复活并任其繁衍。

But scientists might eventually be able to do that with other species that died out more recently than mammoths – like passenger pigeons. This would involve mapping the entire passenger pigeon genome, then mutating a common pigeon’s genome so that it’s akin to a passenger pigeon’s. Voilà: a cloned extinct species.

不过对于那些比猛犸象消失时间迟的物种——比如候鸽,科学家最终可能使其复活。这将需要绘制整个候鸽的基因组,使一只普通鸽子的基因组发生突变以接近候鸽的基因。如此,一个克隆的灭绝物种就产生了。

The science has come a long way since Dolly the sheep was cloned in 1996, says University of Connecticut biotechnology professor Xiuchun (Cindy) Tian, who is working on reactivating nucleus-based DNA through cloning.

康乃狄克大学生物技术教授田秀春(Cindy Tian)认为,自1996年克隆羊多莉诞生以来,科学已经有了长足的进步。目前她正在研究通过克隆在分子层面重新启动DNA。

Controversial conservation efforts are underway to implant white rhino embryos into a surrogate. By one estimate a woolly mammoth-elephant hybrid is only a few years away. In Tian’s estimation, if there were sufficient political will and funding, it would only take 10 years to reach a situation where zoos are populated with rare and even endangered animals.

将白犀牛的胚胎植入代母体内这一极具争议的保护举措仍在展开。据估计,猛犸象与大象杂交的产物也许只需几年就能出现。田教授预测,如果有足够的决心和资金支持,只需要10年的时间就能打造出由稀有甚至濒危动物组成的动物园。

We’re already partway there. In 2000, the San Diego Zoo planned to display a cloned gaur (Indian bison) named Noah, although he died of an infection after two days. The zoo later housed Jahava, a banteng (a type of wild cattle from South East Asia), for seven years, until Jahava broke a leg and was euthanised. Jahava and Noah were both cloned using cells from San Diego’s Frozen Zoo: a collection of frozen skin samples from endangered animals.

我们已经有所成就。2000年,圣地牙哥动物园原计划展示一头名为诺亚(Noah)的克隆白肢野牛(印度野牛),不过它在两天后死于感染。动物园后来成功饲养了一头来自东南亚的爪哇野牛阿哈瓦(Jahava)长达7年,它最终因摔断一条腿被实施安乐死。诺亚和阿哈瓦都是克隆牛,细胞来自圣地牙哥冷冻动物园,该动物园收集了很多濒危动物的冷冻皮肤样本。

So the main obstacles may be financial and political, rather than scientific, Tian says.

因此田教授认为,克隆动物面临的主要问题可能还是经济和政治上的,而不是技术上的。

For one thing, mortality rates for cloned animals are initially very high. Reasons aren’t entirely clear, but likely include reprogramming errors: essentially, the donor egg cell’s nucleus holds on to a kind of genetic memory and resists the replacement with the new genetic material. Animals cloned through this process, known as somatic cell nuclear transfer, “have to survive that first shock after birth”, Tian says. “If they do survive, they’re generally healthy.”

首先,克隆动物初期死亡率是非常高的。原因尚不完全清楚,但可能包括重新编码细胞时发生的错误。究其根本,供体卵细胞的细胞核持有一种遗传记忆,会抵制新遗传物质的替代。田教授说,克隆动物涉及到体细胞核移植,这一过程非常艰难,克隆出来的动物"必须熬过出生后的第一个难关才能存活", "如果能挨过这一关,他们通常都会健康成长" 。

There are ethical concerns about producing animals with a high chance of early death or stress. Still, similar questions might be raised about producing livestock in general. And the success rates are increasing. In 1996, scientists used 277 cloned embryos to get one successful Dolly. “Now if you do cloned cattle, you can transfer 100 cattle cloned embryos and get about 10–20 cloned animals born,” says Tian. "That’s an amazing change.”

人们对于克隆动物较高的早期死亡率和存活压力怀有伦理方面的担忧。同样的问题也存在于一般牲畜的生产过程中。不过成功率确实在提高。早在1996年时,科学家使用277个克隆胚胎才能成功培育一只多莉羊。 "现在如果你生产克隆牛,你可以向100头牛移植克隆胚胎,并获得约10-20只出生的克隆动物,"田教授赞叹道,"这是一个了不起的变化。"

Even so, the higher mortality rates mean that cloning remains very expensive. The only current productive use of animal cloning is for prize beef bulls, whose genetic stock is valuable to farmers. Tian estimates that the cost of cloning a single bull is at least $15,000. Cloning wild or endangered animals would be even more expensive, as we have less information about them and fewer specimens to use as tests.

即便如此,较高的死亡率意味着克隆技术仍非常昂贵。动物克隆目前唯一的有效用途是克隆优质肉用公牛,其基因对农民来说具有很高价值。田教授估计,克隆一头公牛的成本至少为1.5万美元。克隆野生或濒危动物就更贵了,因为科学家对其知之甚少,且可供测试的标本数量也更少。

Clone ranger

克隆管理员

So from a scientific standpoint, it’s well within the realm of possibility to clone endangered animals (and, to a lesser extent, recently extinct ones). If that happens, most of us won’t have much contact with these cloned endangered animals on a daily basis. But one area that might allow non-scientists to interact with clones is in tourism for wealthy individuals.

因此,从科学的角度来看,克隆濒危动物(以及较少数近期灭绝的动物)是完全可能的。如果那一天真的到来,我们大多数人与这些克隆的濒危动物每天并不会有过多接触。但有一个领域可以使专家之外的普通人与克隆动物进行接触,那便是针对富人开展的旅游业务。

If you think your Instagram feed already is full of people showing off novel, specialised travel experiences, that will only increase, according to experts like Daniel Wright, tourism management lecturer at the University of Central Lancashire and author of a paper on cloning and tourism. Jaded travellers might pay through the nose to hunt cloned animals in South Africa, eat cloned animals in Japan, or spot clones of endangered animals while on safari in the US.

赖特(Daniel Wright)是中央兰开夏大学旅游管理专业讲师,并撰写过一篇关于克隆与旅游的论文。他认为,人们的社交网站首页会越来越多地被各种新颖、特别的旅游体验所占据。已经厌倦常规旅行的游客可能会出高价在南非捕猎克隆动物,在日本品尝克隆动物,或是在美国探险的途中观赏克隆的濒危动物。

Right now, adventurous eaters in Japan eat fugu although certain species are threatened by overfishing (and despite the poisonous nature of these pufferfish). Controversially, the Namibian government auctions off several permits each year to hunt the endangered black rhino, arguing that the money is essential for conservation programmes and only non-breeding rhinos can be hunted. Cloning could make both experiences accessible to more visitors.

目前,虽然河豚的一些品种正遭受过度捕捞的威胁,日本一些大胆的食客们仍会食用河豚(尽管这些河豚有毒性)。有争议的是,纳米比亚政府每年都会通过拍卖来允许一些人捕猎濒危的黑犀牛,他们认为这笔资金对于保护计划至关重要,而且只有无繁殖能力的犀牛才能被猎杀。克隆技术可以使更多游客接触到上述这两种体验。

And of course zoos and safari parks around the world already display endangered animals. Many of them participate in biodiversity programmes aiming to keep endangered animals from going fully extinct, or from becoming dangerously inbred as there are so few, for instance, black-footed ferrets.

当然,世界各地的动物园和野生动物园已经展示了一些濒临灭绝的动物。其中许多动物园都参与了生物多样性合作以防止濒危动物完全灭绝,或是因数量极少而近亲繁殖、损害种群繁衍,例如黑足雪貂。

So it could be argued that applying cloning technology for similar tourism purposes is, while expensive, not hugely different from an ethical standpoint. If it’s harmful to support a zoo containing carefully bred animals that will spend their lives in captivity, cloning doesn’t change that.

可以说,将克隆技术应用于发展类似的旅游产业虽然昂贵,但在伦理道德方面它也并没有那么不同。如果说动物园把动物囚在园中精心饲养是有害的,那么克隆也并没有改变这一点。

One person paying close attention to these debates is Carrie Friese, a London School of Economics sociologist and the author of Cloning Wild Life. Friese says that in traditional zoos, animals are the stars; they’re the reasons people come. But in future conservation parks featuring cloned animals, she envisions the technology rather than the animals being the focus. A de-extinction park, for instance, would be about celebrating human ingenuity as much as marvelling at the animals: “The appeal is the ability to bring the passenger pigeon back, as much as seeing the passenger pigeon.”

伦敦政治经济学院社会学家,《克隆野生动物》(Cloning Wild Life)作者弗里斯(Carrie Friese)一直密切关注这些争论。弗里斯说,在传统的动物园里,动物是焦点,人们为它们而来。然而她预想,在未来以克隆动物为特色的保护公园中,焦点会是克隆技术而非仅仅动物本身。例如在一个灭绝动物复活园中,人们在观赏动物的同时也会庆祝人类的聪明才智:"其吸引力不仅在于观赏候鸽,也在于惊叹人类复活候鸽的能力。"

Like Tian, Friese can see these experiences drawing tourists. For instance, some opinion polls show that Americans are more supportive of cloning technology when it’s used for conservation than for any other purpose.

弗里斯同田教授持相似观点,也认为这些体验能吸引到游客。例如,一些民意调查显示,美国人更加支援克隆技术用于保护动物而非其他目的。

The two researchers can also imagine people cloning endangered animals for food. Tian’s research has shown that the meat and milk produced by cloned bovines is safe for human consumption and is largely indistinguishable from non-cloned animal products. She recalls sampling beef from a cloned black bull in Japan, “It was delicious. Many people stayed in line for seconds.” But food supply isn’t the main use for animal cloning at the moment, and some people may be anxious about the safety of eating cloned food.

田教授和弗里斯都预想到今后人们会食用克隆动物制品。田教授的研究表明,克隆牛的肉和奶对人类来说是安全的,且与非克隆动物制品没有很大区别。她回忆自己曾经在日本从一只克隆黑牛身上采集牛肉样品,"味道不错,许多人一直在排队。"但目前食品供应并非动物克隆的主要用途,有些人可能会担心克隆食物是否安全。

Thus, the most likely scenario for future cloned-animal tourism remains a (non-Jurassic) park. Yet as Friese points out, cloning practices raise complicated questions about authenticity and ethics. Would a cloned Pyrenean ibex, whose nuclear DNA is combined with that of domestic goats, be a true ibex? Could a cloned animal from a wild species be considered wild itself? And if zoos and safari parks with access to the latest biotechnology become full of cloned animals in the future, what would the impact be on low-income countries that currently depend on tourism based around wild animals?

因此,关于未来克隆动物旅游的最佳预想还是打造一个圈有非侏罗纪时代动物的公园。不过弗里斯还指出,克隆引发了一系列复杂的关于真实性和道德等问题。核子DNA与家养山羊相结合的克隆庇里牛斯山羊算不算是真正的野山羊呢?野生物种的克隆物其本身还算是野生的吗?如果将来动物园和野生动物园能够获取最新的生物技术,展出许多克隆动物,那么对那些目前依赖野生动物旅游的低收入国家又会产生哪些影响呢?

These aspects are foggy, but one thing is clear. The hype around a costly biotechnological process shouldn’t entirely displace habitat preservation and tried-and-true conservation practices. As Wright puts it, “humans should support and implement measures that aim for preservation of natural environments and to ensure animals and species do not go extinct.”

这些前景都不明朗,但有一点很明确。昂贵的生物技术新潮不应完全取代栖息地保护和其他可靠的保护举措。正如赖特所说的那样,"人类应该支持和实施那些旨在保护自然环境、确保动物和物种不会灭绝的措施。"

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