科学与数学atlasobscura.com
古生物学家试图解释为何化石记录中多为雄性
Paleontologists are trying to understand why the fossil record is mostly males
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这篇文章探讨一个古生物学谜题：化石记录中雄性个体远多于雌性。目前的主流假说认为，年轻的雄性猛犸象等群居动物常独自离群行动，缺乏母系族群的庇护，更容易陷入沥青坑、沼泽等险境而死，而这些地点恰好利于化石保存。
为什么经久不衰：它用现代大象的行为解释远古化石的性别偏差，兼具趣味与科学洞察，多次登上 HN 首页说明这类演化行为学话题经久不衰。
HN 评论精选
概括文章核心假说：雄性离群冒险导致死亡地点更易形成化石
TL;DR 目前最佳假说：研究者认为年轻雄性猛犸象更可能独自离群，远离母系族群的智慧与保护，类似今天的大象社会。换句话说，这些年轻鲁莽的雄象更容易惹上麻烦而死——从陷进坑里到撞上猎人。幸运的是，沼泽、裂隙、湖泊这些死亡地点很利于保存遗骸。它们更容易做傻事，比如死在沥青坑里。
daenz查看英文原文
TL;DR The current best hypothesis: >They figured it was more probable that young male mammoths were much more likely to travel solo, away from the wisdom and protection of matriarchal herds, similar to the way elephant societies function today. In other words, these male mammoths—young, reckless, foolhardy—were just more likely to get into some kind of trouble and die, from getting stuck in a pit to running afoul of hunting humans. Luckily for paleontologists, some of these death sites—bogs, crevices, lakes—are pretty good at preserving remains. “They were more likely to do silly things, like die in tar pits,” Gower says.
用现代大象的 musth 现象佐证雄性更鲁莽的假说
有趣的事实：现代大象中确实有一种现象可以解释雄性更鲁莽的观点。公象会周期性经历“狂暴期”（musth），类似雄性版发情。睾酮水平飙升约60倍，变得极具攻击性甚至暴力，几乎毫无预警地攻击人类和其他动物。南非克鲁格国家公园的一位向导提到，曾有一群进入狂暴期的年轻公象袭击并撞断犀牛的脊椎。我想猛犸象若也有狂暴期，对地形危险大概也不会特别谨慎。
openasocket查看英文原文
Interesting fact: there’s actually a specific phenomenon in modern-day elephants that explains the idea of males being more reckless. Modern elephant males periodically go through a process called musth . It’s sort of like the male version of going into heat. Their testosterone goes up like 60x and they become aggressive and even violent. They’ll even attack humans and other animals with little warning. A guide at Kruger national park in South Africa mentioned that they once had a spree of young bull elephants going into musth and attacking and breaking the spines of rhinoceros. I imagine if mammoths also went through musth they wouldn’t be particularly cautious about terrain hazards and the like
提出采样偏差假说：收藏者偏好大体型标本造成雄性偏多
文章结尾提出了第二个假说，评论里似乎被忽略了但相当合理：人们会保留找到的较大标本，使收藏偏向大体型个体，也就是偏向雄性。当然，可能同时存在多种选择效应。
robotresearcher查看英文原文
Towards the end of the article they state a second hypothesis that seems to be ignored in these comments but pretty plausible: people kept the larger examples they found, skewing the collections in favor of size, and thus males over females. Of course, there could be more than one selection effect at work.
从演化博弈角度解释：雄性高方差冒险策略提高了化石留存率
历史上，典型雄性往往没有后代，而少数雄性有很多（雌性并非如此）。当你的演化中位结果是惨淡的，你就会演化出高方差行为，比如离开部落去探索陌生之地。这导致雄性化石比例更高，因为遗骸保存是极小概率事件，需要特殊条件。
highfrequency查看英文原文
Historically, the typical male had 0 offspring while a minority had many (this was not the case for females). When your median evolutionary outcome is atrocious, you will evolve toward high variance behavior like venturing away from the tribe to explore foreign places. This leads to a higher fraction of male fossils because the preservation of remains is a very unlikely event requiring unusual conditions. "These male mammoths—young, reckless, foolhardy—were just more likely to get into some kind of trouble and die, from getting stuck in a pit to running afoul of hunting humans. Luckily for paleontologists, some of these death sites—bogs, crevices, lakes—are pretty good at preserving remains. 'They were more likely to do silly things, like die in tar pits,' Gower says."
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