A biological point of view on why we have eyebrows.

Bottleneck Effect

Well first let me go over why i find it strange that eyebrows are there. First of all the theory of evolution is that a beneficial mutation will obviously help the organism survive. These mutations may go unnoticed but will be there. The mutated organism breeds with other organisms, lets just use cows as an example. The mutation will take dominance in the genes so if the mutation provides an immunity to say a certain virus that cow will be immune. so back to the evolution theory, say there is an influx of the amount of virus infected cows. The immune ones will survive while most or all of the non immune ones will die. This will cause the cows that are immune to mate since they are the only mating options meaning all the offspring will have this immunization, this does lower the gene pool diversity but leaves all the cows immune to this virus. This is called the bottleneck effect. This bottleneck effect made the cows immune to the virus and helped them survive so the reason i find it strange eye brows are there is because, how did it help humans survive? What made the humans that didn't have eyebrows die?

Catastrophism/Possible Bottleneck on Humans

A possible reason for humans having eyebrows is that in a certain part of the earth there was a mutation that caused people to grow hair above their eyes. The catastrophism theory is that every once and a while an event will occur that wipes out most of the planets organisms, its what predicted happened to the dinosaurs and what may have possibly happened to the early human species. In this case the tribe or group that had eyebrows was the only one left surviving on the whole entire planet. This means that since their whole group had the dominant genes for eyebrows all the young are going to have eyebrows and the humans that evolved from them are going to have eyebrows aside from the ones that mutate again but in the modern day society we as humans are subject to artificial selection which is you choose who you make offspring with opposed to in the wild where animals mate with any other animal of the same species they can find. This artificial selection will be why less genetic variation will be happening to todays human species. There will have been less artificial selection millions of years ago in fact it would most likely be fully natural selection and that is a way that eyebrows may have been permanently built into the human genes. Well atleast my theory anyway.

从生物学的角度解读眉毛存在的必要性

瓶颈效应

哦,先让我想想为何奇怪眉毛长在眼部上方。首先进化论是一种有利的基因突变,明显有助于有机体幸存。这些突变会不经意间出现但的的确确发生在那。突变的有机体和其它有机体“相依为命”。我们就以奶牛为例吧!由于突变在基因中占据中支配地位,因此,如果突变会对某中病毒产生一定的免疫力,那么奶牛就有免疫性。现在我们回到进化论的问题上。假设有大量病毒感染了牛群,有免疫力的奶牛就会幸存而无免疫力的大多数或所有奶牛将无法幸免。有免疫力的奶牛就因此配对,因为这是它们的唯一选择,这样一来它们的幼仔也会有免疫作用,这减少了基因库的多样性但幸免的所有奶牛对病毒均具免疫性。这便是所谓的“瓶颈效应”。它使得奶牛幸免于病毒而活下来,由此得出那原因在于:眉毛是如何使人类幸存下来的?又是什么使得那些没眉毛的人无法幸存呢?

灾变说/人类身上的可能瓶颈

人类长有眉毛,一个可能的原因就是地球某一区域发生过灾变,从而导致人眼上方长有毛发。所谓灾变理论即每隔一定时期后会突发事故,彻底消灭大多数行星的有机体,就像人类预测的曾经发生在恐龙和早期人类身上的灾害事故。为此,那些长有眉毛的部落和人群是整个星球的唯一幸存者。自那些人具备了支配性的眉毛基因后,他们的后代长有眉毛;进化而来的人类长有眉毛;那些再次基因突变的人群也长有眉毛。但在现代社会,作为人类的我们受到“人为淘汰”的影响,可以选择谁是自己的子孙,而不同于野生动物,他们只能和自己找到的同一物种进行交配。这种所谓的“人为淘汰”将是当今人类物种为何发生较小基因突变的最好诠释。事实上在数百万年前很少有这种“人为淘汰”而绝大多数是“物竞天择”,这也就是为什么眉毛永远是人类基因的一部分。好了,无论如何,这至少是我的理论。