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科学美国人60秒:巨型动物的粪便帮助南瓜散播种子

所属教程:科学美国人60秒科学系列 更新:11-28
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We Owe Our Pumpkins to Pooping Megafauna

巨型动物的粪便帮助南瓜散播种子

This Halloween, as you carve jack-o-lanterns and make pumpkin pie, take a moment to appreciate just how far the humble pumpkin has come. "The wild form of a pumpkin looks like a tennis ball and it tastes like one. It's incredibly bitter, it's got a really hard rind, and it's incredibly unpalatable to humans."

在这个万圣节,当你雕刻南瓜灯和做南瓜饼的时候,花点时间来欣赏一下这个不起眼的南瓜已经走了多远。“野生南瓜看起来像网球,尝起来也像。它非常苦,外皮非常硬,对人类来说非常难吃。”

Logan Kistler, an archaeologist at the Smithsonian's National Museum of Natural History. He says, as unpalatable as those early squashes were, they made a tasty tidbit for mastodons. "And we know that because there are deposits of mastodon dung in Florida that are over 30 thousand years old. And so in those mastodon dung deposits, sure enough what we can find are wild squash seeds."

洛根·基斯特勒是史密森尼国家自然历史博物馆的考古学家。他说,尽管早期的南瓜很难吃,但它们是乳齿象的美味佳肴。“我们知道这些是因为在佛罗里达有超过3万年前的乳齿象粪便。所以在那些乳齿象的粪便沉积物中,我们肯定能找到野生南瓜种子。”

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Kistler says mastodons probably weren't put off by the gourds' bitter taste. Because a few years back, his team analyzed the genomes of more than 40 mammals. And they found that the larger the animal, the fewer copies of a bitter-taste-perception gene they tended to have.

基斯特勒说,乳齿象可能不会因为南瓜的苦味而却步。因为几年前,他的团队分析了40多种哺乳动物的基因组。他们发现,体型越大的动物,其感知苦味的基因就越少。

"Turns out there's this absolutely beautiful correlation between body size and the ability to taste bitter compounds. So what we think is going on, is that these are really plants adapted to a landscape with large herbivores. They evolved this bitter toxicity in order to deter small mammals who would destroy the seeds, but they've evolved it at just the right level where large mammals are not put off by the bitterness and they can disperse the seeds."

“事实证明,体型和品尝苦味化合物的能力之间存在着绝对美妙的关联。所以我们认为,这些是适应大型食草动物生存环境的植物。它们进化出这种苦涩的毒性是为了阻止小型哺乳动物破坏种子,但它们进化的程度恰到好处,大型哺乳动物不会被这种苦涩所吓倒,它们可以散播种子。”

Through their poop. Kistler reported those findings in the Proceedings of the National Academy of Sciences in 2015. Along with dispersing seeds, mastodons, like modern elephants, probably stomped around a lot and vacuumed up vegetation—creating the sort of disturbed environments where squash plants thrive. So it was a beneficial match.

通过这些动物的粪便,Kistler在2015年的《美国国家科学院院刊》上报道了这些发现。除了散播种子,乳齿象,就像现代的大象一样,可能会四处踩踏并吸尘吸收植物——创造出一种混乱的环境,让南瓜植物茁壮成长。所以这是一场有益的比赛。

But then, of course, the mastodons died out. And humans, Kistler says, which also tend to disturb the environments around them, creating great squash habitat—may have taken the mastodon's place. The details are murky.

当然,后来乳齿象灭绝了。而人类,Kistler说,也倾向于扰乱他们周围的环境,创造了巨大的壁球栖息地——可能取代了乳齿象的位置。细节尚不清楚。

"The way that the domestication of squashes started is still a little bit of a mystery. Because they're bitter and toxic in the wild and they get to this place of palatability." Perhaps, he says, humans grew the gourds first to use them as storage vessels…and later tamed the bitterness. Either way, squash seeds, stems and rinds discovered in a cave in Oaxaca, Mexico provide evidence that, at least 10,000 years ago, ancient people had already begun domesticating a squash that would, eventually, carve a place for itself as our modern pumpkin.

“瓜类驯化的起源至今仍是个谜。因为它们在野外又苦又毒,所以来到了这个美味的地方。”也许,他说,人类最初种植葫芦是为了将其用作储藏容器,后来才驯服了苦味。不管怎样,在墨西哥瓦哈卡的一个洞穴中发现的南瓜种子、茎和皮提供了证据,证明至少在一万年前,古人就已经开始驯化南瓜,这种南瓜最终会为自己开辟一块地方,成为我们现在的南瓜。

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