MinuteEarth
在“造娃”进行到一半的时候，雌性螳螂有时会突然一口咬掉雄性的脑袋，然后一边继续交配，一边把他慢慢吃掉。
而螳螂并不是个例。很多不同的物种，都会把自己的“恋人”当午餐。不过有一件事非常一致：几乎总是雌性在吃雄性。
为什么“男士们”总是沦为晚餐？
嗨，我是Kate，这是MinuteFood。呃……Kate？哦抱歉！这是MinuteEarth。
确实，很多动物偶尔都会吃掉自己的同类。但我们今天讨论的，是一种更“特别”的现象：当动物在交配前、交配中，或者刚刚交配后，把自己的配偶——甚至潜在配偶——吃掉。这种行为在科学上被称为“性食同类”（sexual cannibalism）。
仔细想一想：雌性是负责产卵或在体内孕育后代的一方。如果雄性在交配前、交配中或交配后把雌性吃掉，那就根本不会有宝宝诞生。因此，那些经常“吃约会对象”的雄性，是无法把这种行为遗传下去的。
所以，真正可能长期形成“吃伴侣”习惯的，只能是雌性。而且有时候，这个习惯确实“很划算”。
比如，如果雄性原本会帮忙养育幼崽，那么杀掉“孩子他爸”显然不太明智。但在许多物种中，雄性并不会参与育儿。雌性必须独自抚养孩子——而且有时候是一大堆孩子——这需要消耗大量能量。
这时候，如果一个高蛋白、现成的“营养餐”就在眼前，那当然是吃掉最划算。
有研究发现，吃掉伴侣的雌性螳螂，产卵数量是那些没吃掉伴侣的两倍以上。
听起来好像“吃伴侣”对雌雄双方都有利——因为后代更多，基因传得更远。但问题在于，雄性被吃掉之后，人生（哦不，虫生）就直接终结了。如果他没被吃掉，他本可以继续交配，一次又一次，留下更多后代。
不过，在某些情况下，被吃掉对雄性来说，反而可能是一种“进化策略”。
以红背蜘蛛为例。交配完成后，雄性往往会主动翻滚进雌性的毒牙之间，把自己送上“餐桌”。
科学家认为，这种“自我牺牲”之所以进化出来，是因为在这个物种中，大多数雄性在找到配偶之前，就已经被捕食者吃掉了。所以，如果一只雄性红背蜘蛛好不容易成功交配，他几乎不太可能再有第二次机会。与其等着被天敌吃掉，不如把自己献给伴侣，让她获得更多营养，从而提高后代的存活率。
前面我们讲了为什么雄性会在交配过程中或之后被吃。那么，如果在交配之前就把潜在对象吃掉，直接导致“零后代”，这又是怎么回事呢？
在某些物种中，比如捕鱼蛛，竞争异常激烈。对雌性来说，足够“凶猛”和具有攻击性，反而是一种优势。但问题是，这种天生的攻击性有时会误伤“准对象”……一不小心就变成了“约会事故”。
总结来说，虽然对我们人类来说，这种行为听起来不可思议，但在某些进化背景下，雌性把“约会对象”摆上餐盘，确实是合乎逻辑的。
说到未来的不确定性——它不仅让人焦虑，还会悄悄影响我们每天做出的许多决定。倒不是说我们会被吃掉，但大多数人终究都会遇到某个时刻：工作不再稳定、不再有意义，或者不够灵活。
感谢TripleTen的支持！
In the middle of baby-making, a female praying mantis will sometimes chomp down on a male’s head, then devour him as she finishes mating with him. And mantises aren’t alone; many different species lunch on their lovers. But one thing is remarkably consistent: it’s almost always the females doing the eating. Why is it dudes that always end up as dinner? Hi, I’m Kate, and this is MinuteFood. Uhhh, Kate? Oh, sorry! This is MinuteEarth. All sorts of critters will occasionally munch on members of their own species, but here, we’re talking specifically about when an animal eats its mate – or potential mate – before, during, or right after babymaking, which scientists call “sexual cannibalism”. And – think about it – since females are the sex that lays the eggs or nurtures the offspring inside their own bodies, if a male eats a female before, during, or right after mating, there won’t BE any babies. So any male who regularly dined on his dates wouldn’t be able to pass along the habit. It can really only be females that make a habit of lunching on their lovers – and sometimes, that habit really pays off. Like, killing off a baby daddy that otherwise would have helped raise the babies doesn’t make a lot of sense. But in species where males don’t help out, the female gets left alone to raise the babies – sometimes a LOT of babies – which takes a lot of energy. So if a convenient, protein-packed snack is, like, RIGHT THERE, it benefits her bigtime to chow down. One study found that mantis females that ate their mates laid more than twice as many eggs as those that didn’t. Which might make it seem like mate-eating helps both female AND male mantises leave behind a bigger genetic legacy. But since the male ends up dead, his future prospects are over; if he hadn't been eaten, he could have gone on to mate again – and again, leaving way more babies behind. In some cases, though, getting eaten does seem to benefit males. After redback spiders mate, the male often somersaults into the female’s fangs, offering himself up to her. Scientists think this self-sacrifice evolved because in this species, the vast majority of males get eaten by predators before they ever get a chance to mate. So if a male redback does get lucky enough to actually get lucky, he’s almost certainly not going to get another chance; he might as well sacrifice himself to his mate to make sure the babies are well-provided for. So we've covered why males get eaten during and after babymaking, but what’s up with eating a potential partner before mating, which guarantees exactly zero offspring from the pair-up? Well, in certain species, like fishing spiders, competition is intense, so it really pays for females to be super aggressive, and all that innate aggression can accidentally end up directed toward a potential mate...oops! The bottom line is that, while it seems unthinkable to us, sometimes it does make sense for females to plate their dates. Uncertainty about your future isn’t just uncomfortable – it quietly shapes a lot of decisions we make every day. And not just cause you might get eaten; most of us will eventually face a moment when a job no longer feels stable, meaningful, or flexible enough. Thanks, TripleTen!
