你身邊仍未揭祕的十個小謎團(下)
Do Birds Migrate?
5.為何鳥兒會遷徙？We know that birds migrate over really long distances every year to lay eggs or to escape harsh winters. What we don't know is how they do it at all. The migration of birds remains one of the most mysterious animal behaviors known to science, and even though they've been trying hard to solve it for a long time, answers haven't been easy to come by.
鳥兒每年都會遷徙至很遠的城市繁殖、過冬，沒有人可以解釋它們這樣做的原因。鳥兒的遷徙至今仍為科學界未解之謎，即便多年來人們想盡辦法去研究這個問題，答案仍未揭曉。
Consider this: Cuckoos migrate and lay their eggs in other birds' nests, then just fly away to their own business. When the young ones grow up, they make their way to their ancestral lands without any help whatsoever. Scientists do believe that they are able to use a variety of compasses based on the stars and the Earth's magnetic field, but a compass can only guide you—it can't tell you the coordinates of a location you should have no idea about. Clearly, cuckoos are one species you don't want to mess with.
試想一下，布穀鳥遷徙，將蛋產於別種鳥的巢中，便過著自由自在的日子。而布穀鳥的幼子長大後，卻可以在沒有父母的指引下，飛回它們祖先棲息的土地。科學家相信布穀鳥可以藉助星星的位置或者地球磁場來辨別南北方向，但指南針只可以引導方向而不能帶領你去一個你根本不知道的地方。顯然，布穀鳥會是一個你並不想惹的物種。
Causes Gravity?
4.引力是如何產生的？
Newton pioneered the study of gravity over 350 years ago, and you'd think that we'd have it all figured out by now. But the more we've progressed in our knowledge of the world, the more baffling gravity has become for researchers. For starters, we know the causing particle for each of the four fundamental forces of the universe—except gravity. A graviton is believed to be that particle, but we're pretty far from actually finding it.
牛頓在350年前開創了力學研究，你可能會認為人類已研究清楚所有關於力學的問題。但當人類對世界瞭解得更多，令人疑惑的力學問題也隨之增多。一開始，人類甚至不知道四大基本力（萬有引力，電磁相互作用力，弱相互作用力，強相互作用力）中的萬有引力。很多人認為萬有引力是微粒，但人類所掌握的知識遠遠未能證明此設想。Another thing about gravity is that it is the weakest of all the other fundamental forces, yet if we look around the world, that doesn't seem to be the case at all. Gravity keeps galaxies together, and it is about 1040 times weaker than the electromagnetic force. The fact that it's so weak makes it all the more difficult to study it in the lab.
另一個有關引力的說法是：引力在四大基本力中最弱。當我們仔細觀察這個世界時，這一說法似乎不可信。引力使星系聚集，但引力卻比電磁相互作用力弱1040倍，亦因為引力微弱，在實驗室難以研究。Do We Store And Retrieve Memories?
3.人類如何儲存與檢索大腦中的資訊？
Science has come a long way toward understanding how our bodies work, but memories are still one of the most perplexing problems of the human anatomy. We just have no idea exactly what parts of the brain are involved in the storage of our memories, though we do know that a lot of areas of the brain are involved in the process. Even more confusing than memory storage is memory retrieval. Scientists have been looking into how our brains trace a particular memory from our memory bank since at least the '20s, but it's still not clear how we do it.
科學研究人類身體機能運作已取得很大進展，但大腦記憶仍是人體解剖學中最複雜的問題。即便我們已經知道大腦很多區域都參與記憶，大腦哪一部位與記憶有直接關係則仍未知曉。相比之下，記憶檢索比記憶儲存更令人費解。科學家在20世紀前已開始研究腦部如何檢索特定記憶，至今仍無結論。What we do know for sure is that it has something to do with neurons and the connections between them. When we see something that triggers a memory to be traced, many parts of the brain interact with each other simultaneously to make us remember it. Beyond that, though, the whole thing is a mystery.
可以確定的是，記憶檢索與神經元和兩者之間的聯絡有關。當我們看見觸發記憶的事物，在大腦各領域的相互作用下，大腦做出記憶。除此之外，一切都只是一個謎。Do Women Go Through Menopause?
2.為何女性有更年期？
Menopause defies all the rules of evolution. The ability to reproduce in the animal kingdom ensures that the species are able to pass on their superior genes, but in humans, something weird happens. Women decisively lose their ability to pass on their lineage at the age of about 45–50, and science just doesn't have any idea why. From an evolutionary perspective, it is always harmful for a species to completely give up their ability to reproduce, as survival by natural selection ceases to take place once that happens.
更年期不符合演變規律。在動物王國中，再生功能使物種傳遞優異基因。但奇怪的事情發生了，人類女性在45～50歲時失去了傳遞基因的能力。從進化論的觀點來看，放棄生育能力對於任何一個物種來說都是有害的。一旦這種情況發生，自然選擇不再有效。One explanation is the grandmother hypothesis, which says that after a point, women should spend more time caring for their grandchildren than their children, but the benefits of that are far inferior to the benefits of giving birth to your own children. It's also not abundantly found in the animal kingdom. Apart from humans, only two species of whale completely stop breeding at a certain age and go on to live for a significant amount of time. Other animals that experience deteriorating sexual abilities, however, often die out soon after.
一種解釋是祖母假說：當女性到了一定年齡時，應花費更多的時間去照顧孫輩而不是兒女，但這樣做並沒有比生育自己的孩子得到更多的好處。“祖母假說”也很少出現在動物世界當中。除了人類，只有兩類鯨會在在特定年齡完全失去生育能力，並能生存很長一段時間，而其他動物性功能衰退後很快就會死去。Are Dreams?
1.夢是什麼？
Dreaming is one thing that's common to us all. It might differ in the way it happens for some of us, but it's definitely a resident feature of all of our brains. You'd think that science would be able to figure out why our brains decide to go in LSD mode every night, but sadly, there are no definite answers as to what exactly dreams are. Some people believe that they're just random images which serve no purpose, while others believe that they carry a deeper meaning, though we're all pretty much guessing here.
夢對於所有人來說都不陌生。對於我們的大腦來說，夢是一個固有特徵，不同的只是夢的內容。也許你認為科學可以解釋大腦為何每晚都大螢幕播放影象，不幸的是，科學也無法給出夢的定義。一些人相信，夢只是一些沒有意義的隨機影像，而有人則認為夢有更深的含義，但大家的猜想並無根據。Some theories suggest that dreams are a manifestation of things we'd rather not think about during the day, like sexual fantasies, though many modern scientists don't agree with that. What they do agree with, however, is that dreams are most likely symbolic of something deep in our psyche, though no one can decisively say what. The jury is divided on whether they serve any purpose at all, and it looks like it's going to take a long time for us to come to a universally accepted answer.
有理論提出夢展現了我們在白天不會想的事情，例如性幻想。但許多近代科學家並不認同此理論。大部分人則認為夢是人類靈魂深處的象徵，但沒有人可以準確說出是什麼。人們對夢是否有意義的看法仍有分歧，普遍接受的理論出現還需要一段時間。翻譯：陳夏瑾 來源：前十網
