Strange evolution: The weird future of life on earth
未来生命：地球可能会演化出哪些奇特生物

In the early 1980s, the author Dougal Dixon published a cult book called After Man: A Zoology of the Future, which imagined what life would look like millions of years from now. Dixon envisaged shrews that use their tails as parachutes, flying monkeys (or “flunkeys”), super-long coiled snakes that strike out to snatch birds mid-flight, nightgliders that impale their prey with long spikes on their chests, and flower-faced birds and bats that fool pollinating insects into landing in their hungry mouths.

上世纪80年代初，古生物学作家道格拉斯‧迪克森（Dougal Dixon）出版了一本名为《人类灭绝之后的未来动物世界》（After Man: a Zoology of the Future）的科幻著作，想象数百万年人类绝迹后地球上的生命形态。在迪克森的未来奇幻世界中，有用尾巴当降落伞的鼩鼱（shrew），飞翔的猴子（flying monkey/flunkey），盘绕卷曲的超级长蛇空中抓捕飞鸟，夜间滑翔动物使用长刺刺杀猎物，脸如鲜花的鸟类和诱惑授粉昆虫落入它们饥饿口中的蝙蝠。

Decades later, Dixon says his book was not an attempt to predict the future, rather it was an exploration of all the possibilities of the natural world. “Popular-level books on evolution, even though it’s not intentional, seem to suggest evolution is something that happened in the past,” he says. “That’s not the case at all. Evolution is taking place today, it will continue to take place well into the future, long after we are gone.”

时过几十年后，迪克森称他这本书并非是想要预测未来，而是要探索自然发展的一切可能性。他说：“有关演化论的科普书籍，即或不是出自本意，看来给人的印象都是生命演化只是过去时。事实当然并非如此。生命的演化今天仍在在进行中，即或人类在地球已经绝迹后的遥远未来，生命的演化仍将继续下去。”

While Dixon’s book was a work of fiction, most biologists agree that millions of years from now Earth will be a very different place. “I think it’s gonna look and feel like an alien planet,” says Athena Aktipis, an evolutionary biologist at Arizona State University.

即或迪克森这本书是科幻著作，但大多数生物学家都同意几百万年后的地球将会是一个完全陌生的星球。亚利桑那州立大学（Arizona State University）演化生物学家阿克逖皮斯（Athena Aktipis）说：“以我之见，遥远未来的地球我们看来和感受会像一颗外行星那般的离奇。”

Whatever evolves will feel foreign and unlikely to us today – just as our current world, dominated by mammals, would have seemed improbable from the perspective of the dinosaur era. So, what might life look like in the future? What creatures could develop in, say, 100 million years, given what we know about life on Earth and the principles of evolution?

无论未来的生命演化如何，今天的人类看到都会觉得怪异和不可思议，如同今天的世界，哺乳动物称霸天下，但要是你自恐龙世纪穿越过来，一定会觉得难以相信。那么，地球遥远未来的生命形态看来将会是什么样？ 比如说，基于我们对地球生命和演化原理的认识，能否推想1亿年之后地球上会演化出什么样的物种？

Let’s start by zooming back millions of years to a much earlier era of life on our planet. In the Cambrian explosion, some 540 million years ago, the Earth became populated by a whole host of “weirdo” and “cartoonish” creatures, according to Jonathan Losos, an evolutionary biologist at Washington University in St Louis.

让我们首先将时光倒流数百万上千万年前，回到我们地球上生命初始的世纪。据圣路易斯华盛顿大学（Washington University in St Louis）的演化生物学家罗索斯（Jonathan Losos）之说，大约5亿4千万年前的寒武纪（Cambrian）大爆发时候，地球上出现一系列“怪异”和“类似今天动画电影角色”的奇特生物。

“The Burgess Shale [in Canada] was inhabited by a veritable bestiary of the bizarre,” he writes in his book called Improbable Destinies: Fate, Chance, and the Future of Evolution. One animal, Hallucigenia, with its thin, tube-like body covered in rows of enormous spines, and stick-like clawed appendages was “similar to something out of a Futurama episode”.

罗索斯所著《不可思议的生命：演化的命运、时机和未来》（Improbable Destinies: Fate, Chance, and the Future of Evolution）一书写道：“栖息在加拿大伯吉斯页岩（Burgess Shale）的生命完全可以称之为怪物。”有一种叫怪诞虫（Hallucigenia）的动物，细长的管状肢体上长满了两排巨大的长刺，以及类似棍子的爪子状附肢，“像是来自动画片《飞出个未来》（Futurama）的东西”。

So, it is not impossible for similarly weird and unusual creatures to evolve in future. “Just about anything plausible you can imagine has evolved somewhere at some point in some species,” Losos argues. “Given enough time, even the improbable will occur eventually.”

因此，生命在遥远的未来演化出如此奇特和怪诞的物种不是不可能的事。罗索斯说：“差不多任何你能想象到的生物形态，都曾在生命演化史的某个地方某个时期在某些物种中出现过，只要演化时间足够，就能化不可能为可能。”

According to Losos, the world of biological possibilities is vast, and we may not have seen everything yet. “I, for one, am not at all convinced that life on Earth has uncovered every conceivable way of existing on a planet like our own, or even most of the ways,” he writes.

按照罗索斯的理论，生命演化之潜在世界广袤无垠，人类尚未能窥其全貌。因此，他在书中如此说道：“如果认为地球上的生命形态已经揭示了如同我们地球这样的星球上生命所有可能存在的方式，或者大多数方式。这样的观点，就我本人而言，实难苟同。”

Still, it’s difficult to predict which of those possibilities we may end up with. Losos’ book analyses the arguments for and against the predictability of evolution: the question of whether history would repeat if we were to “replay the tape of life”. The evidence is split, and we simply don’t know to what extent evolution is predictable and repeatable over long time periods. Add to that an element of chance – a huge volcanic eruption or an asteroid hitting the Earth, and firm predictions become near impossible.

当然，要预言生物究竟如何演化是相当困难的。物种演化能否预测？罗索斯的著作分析了支持和反对的两种观点，提出一个关键问题在于，如果我们想要“再现生命的历程”，演化的历史是否会依旧再来一次。无坚实可靠的证据支持历史会重演，因为物种演化要经历极其漫长的地质年代时间，人类无法知道对未来的演化我们可预测到多少，以及生命史是否会重演。而且还会有不可预料的偶发事件，比如超级火山的爆发，或者小行星撞上地球。所以，物种将来如何演化，今天根本不可知。

Yet, we can make educated guesses.

或许，我们可以根据现有的知识做一些猜测。

First, however, we must address the impact of a major evolutionary force that is already transforming life worldwide: Homo sapiens.

不过，我们首先必须讨论一支正在改变地球生态的演化大军，即我们人类，或曰智人（Homo sapiens）的影响。

If humans thrive for millions of years, they will have a marked effect on future evolution, and natural selection will produce new varieties of life to deal with the altered, and probably polluted, environments that we create. “We may well see the evolution of a bird beak specialised for feeding out of tin cans, or rats developing oily fur to slough off toxic wastewater,” writes Peter Ward, a paleontologist at the University of Washington, Seattle, in his 2001 book Future Evolution.

人类在地球上生生不息，繁殖人口，扩张领土已数百万年，因此可肯定对未来的生命演化的影响必定举足轻重。为适应人类对自然环境的改变和污染，物竞天择，适者生存，就会有新的物种演化而生。西雅图华盛顿大学（University of Washington）的古生物学家彼特·沃德（Peter Ward）2001年出版他的著作《未来的物种演化》（Future Evolution），书中这样认为：“有一天我们很可能会看到鸟喙演化到能够啄食罐头里的食物，或者老鼠长出不沾水的油性皮毛以防被有毒废水污染。”

Ward foresees opportunities for new types of species that possess “weedy” qualities – hardy, adaptable creatures that don’t mind living around humans and are able to make use of their world, such as house cats, rats, raccoons, coyotes, crows, pigeons, starlings, sparrows, flies, fleas, ticks, and intestinal parasites.

按照沃德的预测，地球有可能出现这样的新物种，耐寒、适应性强，具有野火烧不尽，春风吹又生的强韧生命力，愿意附生于人类社会，甚至能够利用人类世界的资源，比如家猫、老鼠、浣熊、郊狼、乌鸦、鸽子、椋鸟、麻雀、苍蝇、跳蚤、蜱虫和肠道寄生虫之类。

On a hotter, dryer Earth warmed by humans, a lack of fresh water may also prompt novel adaptations. “I would imagine animals that would evolve weird specialisations to capture moisture from the air,” says Patricia Brennan, an evolutionary biologist at Mount Holyoke College in Massachusetts. “Larger animals might evolve things like extended sails or skin flaps that they could extend out in the early morning to try to capture moisture. The frilly collars of some lizards, for example, could become very large and exaggerated to gather water in this way.”

人类的活动改变着气候，我们生活的地球正在变暖，变干燥，缺乏淡水亦会影响物种为适应环境而改变。美国马萨诸塞州曼荷莲学院（Mount Holyoke College）的演化生物学家帕翠霞‧布伦南（Patricia Brennan）说：“我会想象动物演化出怪异的特性和本领来获取空气中的水分。块头较大的动物可能会演化出一些好像扬起的船帆或鼓起的皮翼之类的东西，清晨空气潮湿时就伸展开来获取水分。例如，有些蜥蜴的褶边颈圈为收集水分会鼓涨很大很夸张。”

In a hotter world, Brennan also envisages the rise of naked mammals and birds: “Mammals may lose fur in some patches and collect water in skin pockets. In a warming planet, endothermic animals [those that generate their own heat] may have a hard time, so birds in warmer climates may lose contour feathers to prevent overheating, and mammals may lose most fur.”

布伦南还设想在一个变暖的地球上，会演化出无毛的哺乳动物和鸟类，“哺乳动物的某些部位可能会不再有毛，会以身体上的皮囊收集水分。在暖化的星球上，靠自身新陈代谢产生热量的温血动物可能会活得很艰难，因此，在暖化的气候里，属于温血动物的鸟类可能会去掉体外的羽毛以散热，哺乳动物也可能会去掉大部分毛发。”

Future humans may also decide to directly manipulate life – in fact, it’s happening already. As the researcher Lauren Holt wrote for BBC Future’s Deep Civilisation series earlier this year, one trajectory for life on Earth could be a “post-natural” one. In this scenario, genetic engineering, biotechnology and the influence of human culture could redirect evolution down radically different paths, from mosquitoes that contain gene drives to mechanical pollinator drones. The evolution of life would be entwined with humanity’s own desires and needs.

未来的人类或许也会将生命玩弄于股掌之上，事实上，这已经开始。就如研究人员劳伦‧霍尔特（Lauren Holt）今年为英国广播公司未来频道（BBC Future）的《深度文明》（Deep Civilisation）系列节目所写的文章说，地球上生命发展其中的一条轨迹可能是人类干涉的“后自然”走向。在后自然主义的情景中，从基因改造的蚊子到人工授粉无人机，人类操控的基因工程、生物技术和人类文化的影响可能会把物种的演化导向迥然有别的道路。生命的演化将受制于人类的欲望和需求。

However, there are alternative paths for future evolution: for example, our more enlightened descendants may decide to rewild nature and let natural evolution pursue its course, or humans could become extinct (which was the scenario of After Man).

不过，未来生命的演化也有其他的可能选择。例如，人类的后代会比今天的人类更有智慧，有可能会决定放弃干涉自然，让自然重新野生化，让自然的演化自行其自然之道，否则人类就会自取灭亡，这就是《人类灭绝之后的未来动物世界》一书为人类预言的结局。

Extinction in particular can lead to sweeping evolutionary innovation. In essence, a mass extinction resets the evolutionary clock, argues Ward. After previous mass extinctions, he says, Earth’s plants and animals changed radically.

物种灭绝尤其可能导致生命演化的全新局面。沃德指出，物种大灭绝实质上等于重设物种演化的时钟。他说，地球上发生过的5次物种大灭绝，都使得地球上的动植物发生了天翻地覆的变化。

The Permian extinction, around 252 million years ago, eliminated over 95% of marine and 70% of land species, including fin-backed reptiles and massive mammal-like reptiles that ruled the Earth at the time. It made space for dinosaurs to evolve and take over as the dominant land animals, an outcome perhaps as unlikely and unexpected as the take-over by mammals when they replaced dinosaurs after the Cretaceous-Tertiary mass extinction.

发生在大约2.52亿年前的二叠纪（Permian）大灭绝事件，灭绝了地球上95%以上的海洋物种和70%的陆地物种，包括当时横霸地球的背鳍爬行动物和大型哺乳类爬行动物。但这次大灭绝腾出了空间，让恐龙得以演化，随即取代前朝成为陆地上的新霸主。这一结局与发生在白垩纪-第三纪（Cretaceous-Tertiary）大灭绝竟然异曲同工，这次大灭绝意外地让哺乳动物取代了恐龙，成为地球新世界的最强大物种。

“There was not only a turnover, but also what we might call a ‘changeover’,” Ward writes. “Mass extinctions did more than just change the number of species on Earth. They also changed the makeup of the Earth.”

沃德这本书指出：“大灭绝不仅出现了物种的更替，还出现了我们可以称之为物种整体系统的变革。大规模灭绝改变的不仅是地球上物种的数量，还有地球生命的结构。”

Following an extinction, some biologists think it’s possible that whole new lifeforms with new capabilities will evolve; so different that we can’t even imagine what they might be like. For the first billion years or so of life on Earth, for example, oxygen-breathing animals would have been inconceivable, because oxygen was in short supply and cells hadn’t evolved to use it for energy. That changed forever with the Great Oxidation Event, around 2.4 billion years ago, when the arrival of photosynthesising bacteria led to the Earth’s first mass extinction.

一些生物学家认为，在一次物种大灭绝之后，会演化出具有全新能力的全新生命形式，因新旧物种之天差地别，我们根本无法想象全新的物种会是什么样子。例如，在地球上生命的最初10亿年左右，地球上出现以呼吸氧气为生的动物是不可思议的，因为当时地球大气层氧气极少，而且细胞尚未演化到以氧气为能量。到大约24亿年前发生大氧化事件（Great Oxidation Event）后，形势完全逆转，进行光合作用为大气层带来氧气的细菌导致了地球上的第一次物种大规模灭绝。

“The microbes caused the whole planet to have oxygen and that created a huge shift,” says Leonora Bittelston, an evolutionary biologist at the Massachusetts Institute of Technology. “There have been a lot of innovations that could have been hard to predict before they happened – but once they start happening, they do change our planet.”

麻省理工学院的演化生物学家比特尔斯顿（Leonora Bittelston）说：“这种微生物为整个地球带来氧气，结果是天翻地覆的变化。很多新事物在发生之前无人可以预料，不过一旦发生，我们的地球就会改变。”

So, if humans die off, how wild and sophisticated could things get 100 million years from now? Could we see trees starting to walk, or feasting on animals after killing them with toxic fumes or poisonous darts? Could sea life change, with spiders taking to the water, using their webs to net sardines, while fish learn to fly so they can feed on insects and birds? Could deep-sea animals project bright holograms of themselves to fool predators, attract prey or impress potential mates? Perhaps killer whales and catfish will regain their ancestors’ past ability to run on land so that they can hunt more effectively onshore?

因此让我们设想，要是人类绝迹于地球，从今天往前的1亿年内，地球上的生命会变得如何的野性十足和复杂难解？我们是否能看到树木开始行走，或发射毒气或毒飞镖来猎杀动物而食之？海洋生物会改变形态吗？会有蜘蛛游到水里，用蛛网捕捉沙丁鱼？而水中之鱼是否会飞，好在空中捕食昆虫和鸟类？深海动物能否投射出自己明亮的全息影像来欺骗捕食者、吸引猎物或引诱性伴侣？虎鲸和鲶鱼能否返祖，回到陆地捕食猎物？

Could we also see organisms take up residence in previously underexplored habitats: for example, giant, lightweight poisonous fungi floating in mid-air like an aerial jellyfish, entangling and consuming anything they bump into? Or could insects and spiders build silk nests in the clouds and feed on photosynthesising organisms in the sky? And if plants or microbes evolved something like solar panels to track and concentrate sunlight, could green oases of life thrive on frigid glaciers?

我们是否也能看到生物迁居陌生的栖息地？譬如，是否会有巨大而轻盈的有毒真菌飘浮在空中，状如空中之水母，任何动物一旦撞上就会被缠绕而吞噬？是否有在云中筑巢，捕捉在空中进行光合作用之生物的昆虫和蜘蛛？要是植物或微生物演化出类似太阳能光伏板的东西来追踪并聚集阳光，寒冷的冰川能否出现生机盎然的绿洲？

None of these fantastical creatures sound impossible, says Aktipis. A lot of them are based on what already exists in nature: there are seafaring and gliding spiders, there is microbial life in the clouds, and deep sea anglerfish dangle bioluminescent balls in front of them to attract prey. Some populations of killer whales and catfish can beach to hunt for animals on the shoreline, and small independent oases of life thrive on ice where there are residues of cryoconite, a black dust made up of soot, rock and microbes.

阿克蒂皮斯说，这些生物听起来是匪夷所思，但并非不可能。许多想像在自然界本有依据，比如有滑水和空中滑翔的蜘蛛，有栖息在云层中的微生物，有深海琵琶鱼摇摆其生物性发光球来吸引猎物。还有一些虎鲸和鲶鱼种群会有意搁浅海滩猎食岸边的动物。冰上也会出现一些微小的独立绿洲，由烟尘、岩石和微生物组成的冰上微细生态群。

Jo Wolfe, an evolutionary biologist at Harvard University, notes that some trees are able to “walk” very slowly as they move towards sources of water, and thinks it’s possible that trees could evolve to hunt using poisonous gases or even spiked branches. After all, we already have carnivorous plants like the Venus flytrap. She also points to the existence of spiders that eat fish, and says that cloud-dwelling microbes could possibly evolve from the multitude of tiny organisms known as Prochlorococcus that live in the uppermost layers of the ocean.

哈佛大学演化生物学家乔·沃尔夫（Jo Wolfe）发现，真的会有树木能够行走，即是说，这些树木会非常缓慢地向水源方向移动。她认为，树木可能会进化到利用毒气甚至带刺的枝捕猎食物。因为自然界早有了捕蝇草（Venus flytrap）这样的食肉植物。她还指出有食鱼的蜘蛛，并说生活在云层中的微生物可能是从生活在海洋最上层的大量称之为原绿球藻（Prochlorococcus）的微生物演化而来。

In nature, often all it takes for unusual adaptations to develop are extreme environments. Earth already has plenty of those, and that is not going to change. For example, consider how the male anglerfish has responded to the dire shortage of potential mates in the deep ocean. When he meets a female, he actually fuses into her body. “It is so unlikely he'll ever meet another female again that he just gives up and becomes a sperm accessory for her,” says Kristin Hook, a behavioural ecologist at the University of Maryland, College Park. “So, we might see animals doing more things like this, and over time I'd imagine selection favouring animals that can self-fertilise when finding mates is nearly impossible.”

在自然界，一般是极端环境中才能产生反常的演化。地球上此类现象多不胜数，而且会一直如此。我们以深海中的雄性琵琶鱼为例。因为能与其交配的雌性琵琶鱼极少，当雄性有幸邂逅一只雌性时，即干脆融入雌性，与其合体。马里兰大学帕克分校（University of Maryland, College Park）的行为生态学家克里斯婷‧胡克（Kristin Hook）说：“雄性琵琶鱼此生可能再也见不到其他雌性，所以干脆放弃自我，成为雌性的精子附属器官。所以，我们可能会看到动物做更多类似行为事情，随着时间的流逝，我能想象，如果不可能找到交配对象，自然选择会让能自我繁殖的物种获得演化的优势而生存下去。”

Based on what we know of nature, we also shouldn’t assume that future creatures will stay confined to their current habitats. Lynn Caporale, a biochemist and author, points out that some “flying” fish can already catch insects (and even birds), and some fish are able to walk on land, even climb trees. Even squid occasionally fly above the ocean surface, using squirts of water as propulsion and fins that double as wings.

基于我们对自然的认识，我们切勿假设未来世界的生物仍会固守其目前的栖息地而不另寻空间发展。生物化学家兼作家琳‧卡波拉尔（Lynn Caporale）指出，一些“飞鱼”已经能够在空中捕捉昆虫，甚至猎杀鸟类，还有某类鱼竟能上岸在陆地上行走，甚而爬树。甚至乌贼偶尔也会喷水推进，用鳍作翅膀飞出海面。

This potential for habitat-switching leads to some pretty fantastical possibilities. Consider a toad whose gullet swells outward as a large gasbag used to make mating calls. In his book, Ward playfully envisages it evolving into a “zeppelinoid”, a new type of floating animal that will conquer the lower atmosphere. The toad could evolve to make hydrogen out of water and store it in its throat, helping it to hop and eventually float in the air. Its legs – no longer needed for walking – could become dangling tentacles used for feeding and it would evolve to be large to avoid being eaten – maybe even larger than a blue whale. Giant zeppelinoids would float in the air like jellyfish, dragging their tentacles to catch prey such as deer, and grazing on treetops. They would fill the skies and their shifting shadows would dominate the landscape – the age of the flying toad.

陆栖或海栖动物如果能切换栖息地，这是否会产生一些奇幻怪异的生物。不妨以一只蟾蜍为例。蟾蜍求偶时，食道向外鼓胀，壮大如气囊，然后发出求偶的呱呱蛙鸣声。在《未来的物种演化》这本书中，沃德戏虐般假设蟾蜍会演化成"齐柏林飞船（zeppelinoid）"，一种栖息在低层大气中的新型浮游动物。这种离奇的蟾蜍可能从水中提取氢气并储存于咽喉中，将身体变为气球，因此可以腾空而起，最后飘浮在于空气中。因为不再需要陆上蹦跳而行，蟾蜍的腿会变成悬垂的触须以觅食，体型会进化得很大，以避免成为他人的猎物，其大甚至可能超过蓝鲸。这艘巨大的“齐柏林飞船”如同水母漂浮水中一样飘浮在空中，拖着触手捕捉比如鹿这类的猎物，还可以从空中吃树梢上的叶子。在这个想象的飞行蟾蜍主宰时代，飘浮的蟾蜍会满布空中，其漂浮的庞大身躯为大地投下壮观的奇妙幻影。

Zeppelinoids, says Ward, are “a fairy tale – but there is a glimmer of reality in this fable”. There was once the first flying organism and the first swimming organism, and we know that more species quickly evolved from them, as the innovation allowed them to take over a habitat they never had access to before.

沃德说：“齐柏林飞船是一个童话，但这个幻想的角色也有些微现实。”自然演化史曾诞生第一个会飞的生物和第一个会游水的生物，这一突变为这两个物种开辟了新的疆域，随后很快地更多的物种也就演化而生。

Given that our understanding of evolution and genetics is incomplete, and that much will likely depend on chance events, no one can know for sure what future life will look like. Picking the evolutionary winners of the future is like trying to pick winners on the stock market, or forecasting the weather, writes Ward. We have some data for making educated guesses, but also a large degree of uncertainty. “The colours, habits, and shapes of the newly evolved fauna can only be guessed at.”

既然人类还未对演化论和遗传学有充分的认识，而且演化的进程常常受到偶发事件的影响而突变，因而人类是无法准确预测未来地球的生命将会是什么样。沃德认为，要找出在未来演化中的获胜者，就像要事先指出谁是股市赢家，或谁做了正确天气预报一样。我们有一些资料可以做有根据的猜测，但不确定性也非常之高。“未来将演化出来的新生动物，我们只能猜猜颜色、习性和形状而已。”

Losos agrees. “At the end of the day,” he says, “the possibilities are so wide and uncertain that it’s really pointless trying to speculate about what life might look like – there are just way too many degrees of freedom. Life could go in so many different ways.”

罗索斯同意此说。他说：“总而言之，潜在的发展面向是如此之广阔，又如此之不确定，因此试图预测未来生命的形态可以说是刻舟求剑，如做无用之功，因为演化的随意度实在太大。生命可能的呈现方式多不胜数。”

But if the weirdness of present-day life is a guide, we should not discount the possibility that future evolution could go down some truly mind-boggling paths. And a great deal of current natural creativity and diversity remains unexplored.

但要是参考现代生命的千奇百怪，我们就不应低估这一可能性，即地球未来可能会有神乎其神的生命演化形态。实际上，在今天的地球上，尚有许多自然的创造成果和多样模式人类还有待探索认识。

Indeed, Dixon notes that several of the original “purely speculative” creations he described in his After Man book in 1981 were subsequently discovered: for example, walking bats and snakes that can snatch bats from the air. As he reflected in the 2018 edition of the book: “Many’s the time that I have come across some new ecological or evolutionary development and thought, ‘If I had put that in After Man everyone would have laughed’.”

确实如此。迪克森指出，他在1981年出版的《人类灭绝之后的未来动物世界》所描述的一些怪异动物，本是他“纯属猜测”的个人臆想，后来竟然真的在自然界发现，比如地上行走的蝙蝠和空中猎杀蝙蝠的蛇。该书2018年再版时，他在书中如此反思，“有好几次，每当我遇到一些新发现的自然生态系统或演化新形态，就不免想到，‘如果我当时把这些发现写进《人类灭绝之后》，我应该会大笑不止’。”