花蜜中常含有微量酒精，这意味着蜂鸟等传粉者全天都在摄入酒精。尽管摄入量相当于人类的水平，它们却未表现出任何醉酒迹象——这表明它们拥有惊人的进化耐受性。
在首次针对花蜜中酒精成分的大规模调查中，加州大学伯克利分校的生物学家在他们检测的29种植物中，发现至少有26种植物的样本中含有乙醇。大多数花蜜样本仅含微量乙醇，这可能是由酵母发酵糖分产生的。然而，有一个样本的乙醇含量按重量计算达到了0.056%，约为标准酒精度的十分之一。
传粉者摄入多少酒精
尽管这些含量听起来微乎其微，但花蜜是许多物种的主要能量来源。例如，蜂鸟每天摄入的花蜜量相当于其体重的50%到150%。基于这些摄食习惯，研究人员估计，一种常见于太平洋沿岸的安氏蜂鸟每天每公斤体重约摄入0.2克乙醇。这相当于人类饮用大约一份酒精饮料。
尽管摄入量如此规律，但蜜蜂和鸟类在一天中是逐渐摄入酒精的，并未表现出明显的醉酒迹象。该团队早期的研究发现，蜂鸟会饮用酒精含量高达1%的糖水，但当浓度超过该水平时，它们便会开始回避。
醉酒之外的可能影响
即便如此，花蜜中还含有尼古丁和咖啡因等其他已知会影响动物行为的化合物。乙醇可能具有类似的微妙影响。
“蜂鸟就像小火炉。它们燃烧一切的速度非常快，所以你不会预期有任何东西在它们的血液中积累，”与博士后Ammon Corl一起进行花蜜分析的博士生Aleksey Maro说道，“但我们不知道酒精具有什么样的信号传导或食欲刺激特性。除了像人类那样产生醉意之外，乙醇可能还有其他作用。”
“对于所研究物种的觅食生物学而言，可能存在其他种类的有益影响，”加州大学伯克利分校整合生物学教授Robert Dudley补充道，“它们燃烧酒精的速度如此之快，我猜它们可能并没有受到醉酒效应的影响。但这可能对它们的行为产生其他后果。”
Maro、Corl和Dudley于3月25日在《皇家学会开放科学》（Royal Society Open Science）上报告了他们的发现，一同署名的还有伯克利分校的同事Rauri Bowie和Jimmy McGuire，两人均为整合生物学教授兼该校脊椎动物学博物馆馆长。
实验揭示酒精耐受性
早些时候在Dudley办公室外的喂食器进行的实验表明，安氏蜂鸟对糖水中的低浓度酒精（体积百分比低于1%）基本不在意。然而，当浓度达到2%时，它们光顾喂食器的频率大约降低了一半。
* *Draft:* “不知何故，它们在控制自己的摄入量，所以在野外，0到1%可能是比更高浓度更常见的浓度，”他说。 * *Refinement:* "Metering" implies regulating or measuring. "Control" or "regulate" fits well. "Likely concentration" -> 更可能遇到的浓度. * *Final Polish:* “不知何故，它们在控制摄入量，所以在野外，0到1%可能是比更高浓度更常见的浓度，”他说。 * *Sentence 2:*Another study led by former graduate student Cynthia Wang-Claypool found that feathers, including those of Anna's hummingbirds, contain ethyl glucuronide, a byproduct of ethanol metabolism. * *Key terms:* former graduate student (前研究生), Anna's hummingbirds (安娜蜂鸟), ethyl glucuronide (乙基葡萄糖醛酸苷), byproduct (副产物), ethanol metabolism (乙醇代谢). * *Draft:* 由前研究生Cynthia Wang-Claypool领导的另一项研究发现，羽毛，包括安娜蜂鸟的羽毛，含有乙基葡萄糖醛酸苷，这是乙醇代谢的一种副产物。 * *Refinement:* "Led by" -> 主导/领导. "Contain" -> 含有. * *Sentence 4:* This indicates that these birds not only ingest alcohol but process it in a way similar to mammals. * *Key terms:* ingest (摄入), process (代谢/处理), mammals (哺乳动物). * *Draft:* 这表明这些鸟类不仅摄入酒精，而且以类似于哺乳动物的方式代谢它。 * *Refinement:* "Process" in a biological context usually means metabolize. * *Sentence 5:* Together, these findings suggest that birds and other animals, including human ancestors, may have evolved a tolerance for and sometimes even a preference for alcohol.
* *Key terms:* findings (发现), human ancestors (人类祖先), evolved (进化), tolerance (耐受性), preference (偏好). * *Draft:* 总之，这些发现表明，鸟类和其他动物，包括人类祖先，可能已经进化出了对酒精的耐受性，有时甚至是偏好。 * *Sentence 6:*"The laboratory experiment was showing that yes, they will drink ethanol in their nectar, though they have some aversion to it if it gets too high," Corl said. * *Key terms:* laboratory experiment (实验室实验), nectar (花蜜), aversion (厌恶/排斥). * *Draft:* “实验室实验表明，是的，它们会喝花蜜中的乙醇，尽管如果浓度太高，它们会有些排斥，”Corl说。 * *Sentence 7:* "The feathers are saying that, yes, they will metabolize it. * *Draft:* “羽毛（的分析结果）表明，是的，它们会代谢它。 * *Refinement:* "The feathers are saying" is metaphorical. "羽毛证据显示" or just "羽毛表明". Let's stick to the literal but smooth flow. * *Sentence 8:* And then this study is saying that ethanol is actually pretty widespread in the nectar they consume."
* *Key terms:* widespread (广泛存在). * *Draft:* 而这项研究则表明，乙醇在它们摄入的花蜜中实际上相当普遍。” * *Sentence 9:*Comparing Alcohol Intake Across Species
* *Draft:*跨物种酒精摄入量比较
(Keep bolding as per source style). * *Sentence 10:*After measuring ethanol levels using an enzymatic assay, the team estimated daily alcohol intake for several nectar-feeding species based on their caloric needs. * *Key terms:* enzymatic assay (酶法测定/酶联免疫测定 - usually just 酶法测定 in this context), estimated (估算), daily alcohol intake (每日酒精摄入量), nectar-feeding species (食蜜物种), caloric needs (热量需求). * *Draft:* 在使用酶法测定测量乙醇水平后，团队根据热量需求估算了几种食蜜物种的每日酒精摄入量。 * *Sentence 11:* Because detailed feeding data are limited, they focused on two hummingbird species, including the Anna's hummingbird, and three species of sunbirds, which in South Africa feed on plants such as honeybush (Melianthus major). * *Key terms:* detailed feeding data (详细的进食数据), sunbirds (太阳鸟), honeybush (蜜灌木/蜂蜜茶树 - *Melianthus major* is often called honey flower or honeybush, though true honeybush is *Cyclopia*. *Melianthus major* is usually "Honey Flower" or 大花蜜灌木. I will use the scientific name translation or common name. *Melianthus major* = 大花蜜灌木/蜜花. Let's check standard translation. *Melianthus major* is commonly "蜜花" or "大花蜜灌木". "Honeybush" in the text might be a colloquial reference or specific local name. I will translate as "蜜灌木" or "蜜花" and keep the Latin name). * *Correction:* *Melianthus major* is commonly known as "Honey flower". The text says "honeybush". I will translate "honeybush" as 蜜灌木 and put the Latin name in brackets. * *Draft:* 由于详细的进食数据有限，他们重点关注了两种蜂鸟（包括安娜蜂鸟）和三种太阳鸟，后者在南非以蜜灌木等植物为食。 * *Sentence 12:* Sunbirds fill a similar ecological role in Africa as hummingbirds do in the Americas.
* *Key terms:* ecological role (生态位/生态角色). * *Draft:* 太阳鸟在非洲扮演着与美洲蜂鸟相似的生态角色。 * *Sentence 13:*The researchers also compared these values with other animals, including the European honeybee, the pen-tailed tree shrew, fruit-eating chimpanzees, and humans consuming one standard drink per day (0.14 grams/kg/day). * *Key terms:* European honeybee (欧洲蜜蜂), pen-tailed tree shrew (笔尾树鼩), fruit-eating chimpanzees (食果黑猩猩), standard drink (标准饮酒量). * *Draft:* 研究人员还将这些数值与其他动物进行了比较，包括欧洲蜜蜂、笔尾树鼩、食果黑猩猩，以及每天饮用一份标准酒量的人类（0.14克/千克/天）。 * *Sentence 14:* The tree shrew had the highest intake at 1.4 g/kg/day, while the honeybee had the lowest at 0.05 g/kg/day. * *Draft:* 笔尾树鼩的摄入量最高，为1.4克/千克/天，而蜜蜂的摄入量最低，为0.05克/千克/天。 * *Sentence 15:* Nectar-feeding birds fell in a similar range, consuming about 0.19 to 0.27 g/kg/day when feeding on native flowers.
* *Key terms:* native flowers (本土花卉/原生花卉). * *Draft:* 食蜜鸟类的摄入量处于相似范围，当以原生花卉为食时，摄入量约为0.19至0.27克/千克/天。 * *Sentence 16:*Interestingly, the feeder experiments suggest that Anna's hummingbirds may ingest even more alcohol from fermented sugar water in feeders (0.30 g/kg/day) than from natural nectar.
* *Key terms:* feeder experiments (喂食器实验), fermented sugar water (发酵糖水). * *Draft:* 有趣的是，喂食器实验表明，安娜蜂鸟从喂食器中发酵糖水摄入的酒精（0.30克/千克/天）可能比从天然花蜜中摄入的更多。 “这些研究表明，针对饮食中普遍存在的乙醇，动物界可能存在广泛的生理适应机制；我们在人类身上观察到的反应可能并不具有代表性，无法代表所有灵长类动物或所有动物，”达德利说。“对于那些终生每天都在摄入乙醇的动物而言，也许存在其他的生理解毒途径，或者乙醇具有其他种类的营养效应。这正是有趣之处——这种摄入贯穿全天，属于慢性过程，但这更是一种断奶后持续终生的暴露。这意味着乙醇摄入的比较生物学值得进一步研究。”