2008/05/23：
人类或许不再需要的五个器官（下）
以下五个器官是最有可能的退化而无用的。来源：newscientist
上篇在这里
3.达尔文点（小耳尖）
在妊娠的第六周，六个突起组织在耳孔周围出现。这些最后将形成外耳。达尔文的点，是在第四和第五小突出结合部的小小形变。有相当的人群 (大约10.4%) 在他们的外耳顶端被赋予了这个小小的软骨。如今看来这是一个退化了的关节组织，祖先的外耳上端是可以旋动，并且向下覆盖外裸的耳孔的。维基百科英文
从科学角度看这一先天缺陷，他对我们没有任何害处，我们为之动手术，往往只是为了美容和化妆。然而，纽约市眼耳疗养院的整形外科医生安东尼斯克拉法尼告诉我们，内在的基因遗传学述说了一个有趣的故事。这一特性是个显性基因，也就是说，只要一条基因满足条件即可。说明这一特性是比较强势的，然而，这一基因又有很多变体，意味着即便你拥有这一基因，你也得不到小耳尖。变种的出现又意味着，小耳尖已不再拥有遗传优势。
4.尾骨
组织结构如果缺少进化压力，可能在一定程度改变表现形式，产生变异。人类的尾骨是个很好的例子，哺乳动物的尾骨退化，拥有了修正的功能，较显著的是，尾骨作为肌肉的锚点，为肛门定位。
人类的尾骨一般是由四节脊椎骨合并退化而构成的一根骨头。“这里发生了令人惊异的变异”， 新泽西的纽瓦克州立医学院的尾骨疼痛服务中心主任，帕特里克。他说到，生来六指非常稀少，而尾骨可以有这种数量上的变动，他们常常由不确定的3到5块骨头构成。甚至于，有上百例的医学报告说婴孩出生带有尾巴。如果胚胎发育过程中，停止脊椎生长发育的信号没有及时给出，这一返祖现象的出现机率就会增加。
5.智齿
大多数灵长类动物有智齿（第三大臼齿） ，但少数物种，包括狨猴和绢毛猴没有。乔治华盛顿大学，人类学家彼得卢卡斯：“他们可能是进化中的矮子。”他阐述道，当哺乳动物的体型趋小，很快的，他们的颚部变得不够容纳所有的牙齿了，拥挤导致物竞天择了较小或较少牙齿的物种。这些似乎在智人阶段发生了。
南伊利诺斯州大学的罗伯特科鲁奇尼认为，对人类而言，在过去的四个世纪，食物更加柔软，更多的加工，从而，拥挤的问题更加严重了。臼齿的磨损减少，颚部的空间更加值钱。“因而第三臼齿，我们的最后一颗长出的牙齿很难找到生长的空间。”他说到。不仅”挤压中的智齿“，这一现象非常普遍，更有35%的人群压根没有智齿了。我们可能处于一个最终失去智齿的进化历程中。
#小耳尖很可爱 ₪
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[...] 下篇在这里 [...]
智齿会疼的，我感觉得到
这个耳朵怎么那么红？
猴子在说她坏话？
据说有拔智齿瘦脸的
智齿名字好听，但是肿起来真折磨人……
看到“3.达尔文点（小耳尖）”的时候，应该大家都摸了摸自己的耳尖吧？
还真是……
内个，我四颗智齿长全了……
@Dickey，我有的
我的尾骨处有毛。。。
我有三颗智齿~疼死俺了~
为什么没有我期待的 扁桃体…
我一直觉得这东西没用….还经常发炎
@X: 大嘴！
“更有35%的人群压根没有智齿了”,这句话中听，我到现在还没长，真不想长~听说很痛苦
非常感谢，长知识了，尤其是那个耳尖。
啊哈哈·耳尖···
以后我可以严肃地说，我的达尔文点有点小痒。。。
扁桃体~上有扁桃腺吧~
这个是管大脖子的~ 我可不想以大脖子为美~
原来那叫智齿啊，我以为我多长了一颗牙齿呢，好疼，上次出血了都
我什么也不想扔……
啦啦啦~我家人是属于没有智齿的~但是有小耳尖（比图中的小）。。。
另，小脚趾指甲是两瓣的。。这个据说是匈奴人的后裔？！我有。。。
小耳尖~精灵的耳朵~~
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