What’s the First Species Humans Drove to Extinction?

第一个因人类而灭绝的物种

Sometime in the late 1600s, in the lush forests of Mauritius, the very last dodo took its last breath. After centuries of untroubled ferreting in the tropical undergrowth, this species met its untimely end at the hands of humans, who had arrived on the island less than 100 years before. With their penchant for hunting, habitat destruction and the release of invasive species, humans undid millions of years of evolution, and swiftly removed this bird from the face of the Earth.

17世纪末的一天，最后一只渡渡鸟在毛里求斯茂密的丛林中吐出了最后一口气。在热带丛林中无拘无束的繁衍了数个世纪后，这一物种因为人类而过早的迎来了自己的末日，要知道人类抵达这座岛屿还不足百年。人类对捕猎的嗜好，对栖息地的破坏，同时还带来了入侵物种，抹杀了渡渡鸟数百万年的进化，轻而易举的就让它从地球表面上消失。

Since then, the dodo has nestled itself in our conscience as the first prominent example of human-driven extinction. We’ve also used the dodo to assuage our own guilt: the creature was fat, lazy and unintelligent – and as popular story goes, those traits sealed its inevitable fate.

自此，渡渡鸟作为首个因人类而灭绝的著名案例而扎根于我们的良知中。我们也曾试着用渡渡鸟来减轻自己的负罪感：它们又肥又懒智商又低——而正如受欢迎故事的走向那样，它们的这些特点导致了其不可避免的命运。

But in fact, we couldn’t be more wrong, said Julian Hume, a paleontologist and research associate with the National History Museum in the United Kingdom. He studies the fossils of extinct species, and has devoted a portion of his career to correcting the dodo’s dismal reputation. By digitally modelling the remains of a dodo’s skeleton, he’s produced a 3D digital reconstruction that draws an altogether different picture of a bird that was faster, more athletic and far brainier than popular culture has led us to believe. “It was nothing like this big, fat, bulgy thing that was just waddling around. This bird was super adapted to the environment of Mauritius,” Hume told Live Science. Instead, humans’ unrelenting exploitation was the real culprit behind the dodo’s untimely death.

但根据古生物学家Julian Hume所说，事实上我们大错特错了。他专门研究已灭绝动物的化石，还会用工作上的一部分时间来为渡渡鸟正名。他对一只渡渡鸟骨骼标本进行3D数字重建，得出了完全不同的一种结论——更快、更矫健而且比流行文化中的形象要更加聪明。Hume说：“它根本就不是什么又大又肥又臃肿，只会在地上跑的傻鸟。渡渡鸟非常适应毛里求斯的环境。”而人类无止境的开发才是渡渡鸟灭绝的真凶。

But that’s not all we’ve gotten wrong. Despite the commonly held belief, the dodo actually wasn’t the first creature that humans drove to extinction – not by a long shot. In fact, humanity was wiping out the world’s fauna thousands of years before we set eyes on the dodo. “There was certainly a lot more going on before and after that event,” said Hume.

我们错的不止这一点，因为渡渡鸟其实不是人类导致灭绝的第一种生物——绝对不是。其实早在人类见到渡渡鸟的数千年前，我们就已经在大肆摧毁着全球的动物群。Hume说：“在渡渡鸟灭绝的之前和之后，必定有着很多的灭绝事件。”

So, if the iconic dodo wasn’t the first species we drove to the brink, then which animal gets this disheartening title, instead?

如果标志性的渡渡鸟并非我们导致灭绝的第一个物种，那是什么动物能获此“殊荣”呢？

 

Humans on the move

四处迁徙的人类

We’ve grown accustomed to thinking about human-driven species extinction as a relatively recent trend in our history. Yet, researchers have found convincing palaeontological evidence that dismantles that idea.

我们已经习惯认为人类导致的物种灭绝是人类历史中较近期的事情。不过研究人员已经发现了令人信服的古生物学证据可以驳斥这一观点。

“The real problem started when we, as humans, started migrating,” Hume said. That starting point is still debated, but most recent estimates suggest that migrations that led to lasting populations of humans spread across the globe began with the movement of hominids – Neanderthals and other ancient human relatives, as well Homo sapiens – out of Africa and southeast Asia, roughly 125,000 years ago. This is where the evidence gets interesting. As humans left their ancestral homes, and over the following tens of thousands of years went on to colonize Eurasia, Oceania, North and South America, the fossil record shows a parallel uptick in the extinction in large-bodied animals – also known as megafauna – across those continents.

Hume说：“当人类开始迁徙后才出现了真正的问题。”具体的迁徙起始时间点还有争议，不过最新的推算表明致使人类持续繁衍遍布全球的大迁徙开始于原始人类——尼安德特人和其他古人类亲戚，还有智人——走出非洲和东南亚，距今约有12.5万年。证据在这个地方变的有趣起来。随着人类离开祖先的土地，并且在接下来的数万年里前往开拓欧亚大陆、大洋洲、北美洲和南美洲，化石记录显示出在这些大陆上的大型动物的灭绝也出现了平行上升。

“As [hominids] migrated out of Africa, you see this incredibly regular pattern of extinction,” said Felisa Smith, a professor of ecology and evolutionary biology at the University of New Mexico, who studies how animals’ body sizes have changed over the course of history. As she and her colleagues explained in a 2018 study published in the journal Science, each time our ancestors set foot in new places, fossil records show that large-bodied species – the humongous prehistoric relatives of elephants, bears, antelope and other creatures – started going extinct within a few hundred to 1,000 years, at most. Such rapid extinction timescales don’t occur at any other point in the last several million years (not since the non-avian dinosaurs were wiped out by an asteroid about 65 million years ago.) “The only time you see it is when humans are involved, which is really striking,” Smith said.

“随着原始人类走出非洲，你就能见到这种异常规律的灭绝模式。”新墨西哥大学的生态学和进化生物学教授Felisa Smith表示。正如她和同事在2018年《科学》期刊上发表的研究文章中所解释的那样，每当我们的祖先踏足一个新地方，就有化石记录表明这里的大型动物——大象、熊、羚羊和其他生物的巨型史前近亲——会在几百年的时间里灭绝，最多不超一千年。这种快速灭绝的时间尺度在过去的数百万年里都没有出现过。Smith说：“你见到的都是和人类有关的，很惊人。”

Some of those early lost species would seem like fantastical beasts if they roamed Earth today. For example, “There was an armadillo-like thing called the glyptodon, which was the size of a Volkswagen bus,” Smith told Live Science. Glyptodons, many equipped with vicious-looking spiked tails, disappeared from the Americas at the end of the last ice age, roughly 12,000 years ago – which is probably connected to the earlier arrival of humans there. The number of gigantic Eurasian cave bears, several hundred pounds heavier than grizzly bears today, went into a steep decline about 40,000 years ago, around the same time that humans began to spread across their habitat. South America was once home to lumbering giant ground sloths – and humans were also the most likely candidate in their demise, about 11,000 years ago.

早期灭绝的物种中如果有一些还活在当今的地球上，看似会像是奇幻野兽。比如说，“有一种和犰狳很像的动物，叫雕齿兽，体型跟大众的巴士差不多”，Smith告诉Live Science说。雕齿兽在距今约12000年前的上个冰河期的末尾从美洲大陆上消失——这可能和早期抵达美洲的人类有关。欧亚大陆上生活的巨型洞穴熊比现在的灰熊要重上几百斤，它们的种群数量在距今约4万年前急剧下降，大约和人类开始在它们栖息地生活繁衍的时期相同。

What made large animals, in particular, so susceptible to humanity’s spread? Megafauna likely represented food, or a threat, to incoming humans. What’s more, animals that had never encountered humans before were probably unwary of these strange newcomers migrating into their unspoiled lands, which might have increased their vulnerability to attack. Unlike other smaller animals that breed more rapidly, megafauna also reproduce more slowly and so have smaller populations compared with other species, Hume explained: “So if you take out a big section of [a population] they cannot reproduce quickly enough to build up numbers again.”

是什么使得大型动物尤其容易受人类分布的影响呢？对于初来乍到的人类来说，巨型动物可能象征着食物或者是威胁。此外，此前从未见过人类的动物们可能没有警惕这些新来的陌生物种，或许这也使它们更容易受到攻击。和其他那些繁殖速度更快的小型动物不同，巨型动物的繁殖速度更为缓慢，所以比起其他物种来说，种群数量也更少。Hume解释说：“所以如果你杀死了很大的比例，那它们的繁殖速度跟不上，就无法恢复种群数量。”

It wasn’t just hunting that posed a threat – but also the spread of human-caused fires that would have destroyed swathes of habitat, and increasing competition from humans for food. For instance, it’s thought that by preying heavily on the same herbivores, growing numbers of hungry humans helped drive the extinction of the short-faced bear, a gigantic South American species that once stood at over 10 feet (3 meters) tall, and died out roughly 11,000 years ago. Climate change, paired with human impacts like hunting, also proved to be a lethal combination for some megafauna – most famously, mammoths, which went extinct about 10,500 years ago (except for the dwarf woolly mammoth, which survived until about 4,000 years ago on an island off northern Russia). “If you combine climate change with a negative human impact, it’s a disaster,” said Hume.

 

造成威胁的不止是打猎——人类导致的火灾的扩散也摧毁了大片的栖息地，并且加剧了动物和人类之间的食物竞争。比方说，人们认为由于大量捕食相同种类的食草动物，饥饿人类数量的增加促使了短面熊的灭绝。短面熊生活在南美洲，体型硕大，站立起来的高度可超3米，在距今大约1.1万年前灭绝。气候变化和人类活动也被证明是一些巨型动物的末日组合——著名的猛犸象在距今约10500年前灭绝。Hume说：“如果把气候变化和一种负面的人类活动组合在一起，那就是一场灾难。”

 

An answer?

答案？

All of this is to say that humans have systematically wiped out the species around us from almost the beginning of our history. Our migration prompted “a disaster across the world,” said Hume. “We weren’t very pleasant.” Unfortunately, we’ve continued our ancestors’ legacy, with, among thousands of other species, the eradication of Madagascan hippos 1,000 years ago, the loss of moa birds in New Zealand 600 years ago, and the decimation of passenger pigeons 106 years ago. We are also responsible for ongoing extinctions today.

所有都表明，人类几乎是从人类历史的一开始就已经在系统性的抹杀我们周围物种的存在。“我们的迁徙促使了一场全球灾难，”Hume说，“我们真是一点都不讨喜。”不幸的是，我们接过了祖先的衣钵，在1000年前杀光了马达加斯加河马，在600年前的新西兰又让恐鸟绝种，在106年前大量捕杀旅鸽，还有成千上万个物种的灭绝。而目前物种的持续灭绝，我们也难辞其咎。

But this still hasn’t answered the question of what species went extinct first. And here’s the catch: the data on human-driven extinction across the planet is only reliable as far back as about 125,000 years – but that doesn’t mean we weren’t driving animals to extinction before that in Africa, too. In fact, there’s compelling evidence to suggest that before humans migrated out, they unleashed their hunting instincts on species there as well.

但仍没有回答之前的问题，首个灭绝的动物是什么？重点是：人类导致物种灭绝的可靠数据最早只能追溯到距今约12.5万年前——但这不意味着人类还在非洲的时候就没有导致动物灭绝过。事实上有令人信服的证据表明，人类在迁徙出非洲之前就已经对其他物种释放自己的捕猎天性了。

Smith’s research has revealed that the average body size of African animals 125,000 years ago was only half that of species that were present on other continents around the world. “Africa is one of the largest continents, so it should have had a mean body size similar to that of the Americas and Eurasia where it was roughly about 100 kilograms [220 lbs.],” Smith said. “The fact that it didn’t suggests that there had already been an effect of hominids on megafauna in Africa, prior to 125,000 years ago.”

Smith的研究揭示了12.5万年前的非洲动物平均体型仅有世界其他大陆上的物种的一半。“非洲是面积最大的大陆之一，所以非洲大陆上的动物也应该有着类似于美洲和欧亚大陆那样体重大约在100公斤的平均体型，”Smith说，“但事实上它并没有证明非洲的原始人类在12.5万年前就已经对巨型动物产生了影响。”

In essence, because the rest of history tells us that humans are good at dispatching the largest creatures in an ecosystem, we can make a fairly safe assumption that hominids in Africa at the time could have been responsible for extinctions going even further back in time.

本质上来说，由于剩下的历史告诉我们人类非常善于杀死一个生态系统中体型最大的生物，所以我们可以做一个相当可信的推断，即当时在非洲的原始人类导致了更久以前的物种灭绝。

Still, there’s no way to know for sure what that ‘first’ species would have been – though Smith takes a wild guess: “It was probably some species in the elephant family. But whether that’s palaeomastodon, or stegodon” – the latter being a behemoth with tusks that measured 10 feet (3 meters) long – “I couldn’t tell you.”

可是仍然无法确定哪个物种的灭绝才是“第一个”——不过Smith大胆的猜测道：“可能是象科中的某个物种。但我也不知道到底是古乳齿象还是剑齿象。”——后者是种巨兽，光象牙就有3米长。

Clues for the future

未来的线索

We may not have a clear answer to that original question – but perhaps the more important one to ask is what humanity’s legacy of extinction can teach us about conservation, going into the future.

对于最初的问题，我们可能没有一个准确的答案——但或许更重要的问题是人类导致物种灭绝能教会我们如何在未来更好的保护物种。

Past extinctions have revealed that when animals – especially megafauna – disappear, there are profound ecological consequences. Whole landscapes are transformed in the absence of their shaping effects, with changes to vegetation and species diversity. Smith has even published research showing that the decline of global megafauna in past millennia led to dips in the amount of methane they burped out – with potentially transformative consequences for global climate. What’s more, when animals disappear, whole rafts of dependent species go down with them. The iconic dodo presents one such cautionary tale: when the birds died out, so did a Mauritian dung beetle that relied on dodo feces to survive.

以往的灭绝事件表明，当一种动物消失后，尤其是巨型动物消失后，会有着深远的生态影响。没有了它们的塑造效应，整个地貌会发生转变，植被和物种多样性也会发生改变。Smith也发表过研究文章，显示出在过去一千年里全球巨型动物种群的缩减导致它们排放的甲烷总量下降——对全球气候有着潜在的变革影响。此外，当某种动物灭绝后，这艘“巨轮”上所承载的依附物种也会迎来灭顶之灾。渡渡鸟灭绝后，靠渡渡鸟粪便生存的毛里求斯蜣螂也随之灭绝了。

Understanding human-driven extinctions of the past can help us figure out what the environmental consequences have been, explained Smith, and how we can limit those in the future by protecting the species that remain. Even the dodo’s extinction provides clues that are helping us preserve ecosystems today. Hume is working on a project to catalog pollen spores present in the sediments around dodo fossils, to build up a detailed picture of the lush, palm-fringed forests they once roamed. That’s helping conservationists to rewild the island with vegetation that was once there. “We’re actually reconstructing the exact species of plants and trees from the environment the dodo was living in, before humans arrived,” Hume said.

Smith说，理解过往人类导致的灭绝能帮助我们弄清环境影响是怎样的，以及未来我们如何通过保护剩余的物种来限制影响。即便是渡渡鸟的灭绝也提供了线索，帮助我们保护当前的生态系统。Hume正在从事一个项目，为渡渡鸟化石周围沉积物中的花粉孢子进行编录登记，以便详尽的重现出渡渡鸟曾经生活过的繁茂的棕榈密林。这能够帮助环保主义者使用曾经生长在这里的植被来重新野化这座岛屿。“我们实际上在用人类到达前，渡渡鸟曾经生活的环境中的那些植物和树木来进行重建。”Hume说。

A bit of paradise was lost when we drove the dodo to extinction – not to mention the thousands of species whose demise came before that. But perhaps with hindsight, and the willingness to learn from our mistakes, some of that can be reclaimed.

当我们把渡渡鸟逼到灭绝后，就失去了一部分天堂——更不用说在此前已经灭绝的成千上万的物种。但或许有了后见之明，还有从错误中学习经验的意愿，有些错误是可以改正的。

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