This weekly roundup thread is intended for all culture war posts. 'Culture war' is vaguely defined, but it basically means controversial issues that fall along set tribal lines. Arguments over culture war issues generate a lot of heat and little light, and few deeply entrenched people ever change their minds. This thread is for voicing opinions and analyzing the state of the discussion while trying to optimize for light over heat.
Optimistically, we think that engaging with people you disagree with is worth your time, and so is being nice! Pessimistically, there are many dynamics that can lead discussions on Culture War topics to become unproductive. There's a human tendency to divide along tribal lines, praising your ingroup and vilifying your outgroup - and if you think you find it easy to criticize your ingroup, then it may be that your outgroup is not who you think it is. Extremists with opposing positions can feed off each other, highlighting each other's worst points to justify their own angry rhetoric, which becomes in turn a new example of bad behavior for the other side to highlight.
We would like to avoid these negative dynamics. Accordingly, we ask that you do not use this thread for waging the Culture War. Examples of waging the Culture War:
-
Shaming.
-
Attempting to 'build consensus' or enforce ideological conformity.
-
Making sweeping generalizations to vilify a group you dislike.
-
Recruiting for a cause.
-
Posting links that could be summarized as 'Boo outgroup!' Basically, if your content is 'Can you believe what Those People did this week?' then you should either refrain from posting, or do some very patient work to contextualize and/or steel-man the relevant viewpoint.
In general, you should argue to understand, not to win. This thread is not territory to be claimed by one group or another; indeed, the aim is to have many different viewpoints represented here. Thus, we also ask that you follow some guidelines:
-
Speak plainly. Avoid sarcasm and mockery. When disagreeing with someone, state your objections explicitly.
-
Be as precise and charitable as you can. Don't paraphrase unflatteringly.
-
Don't imply that someone said something they did not say, even if you think it follows from what they said.
-
Write like everyone is reading and you want them to be included in the discussion.
On an ad hoc basis, the mods will try to compile a list of the best posts/comments from the previous week, posted in Quality Contribution threads and archived at /r/TheThread. You may nominate a comment for this list by clicking on 'report' at the bottom of the post and typing 'Actually a quality contribution' as the report reason.
Jump in the discussion.
No email address required.
Notes -
Off topic, but this is my area so I can't resist.
The key thing to understand about the evolution of complex biological systems is that they didn't just pop up fully-formed. Instead, they evolved through a series of small changes to simpler systems. The changes which worked better than the original were passed on to the next generation, and the next generation had a more functional but more complex version of that system. The story of the eye's development goes something like this:
Billions of years ago, a cell contained some retinal. Retinal is a simple molecule that has a special property: when light hits it, one of its double bonds can switch between the cis and trans conformations. The cell can then extract energy (in the form of a proton gradient across a membrane) by flipping it back. Being able to harvest energy from light was a massive advantage, and this adaptation spread like wildfire. An explosion of thriving life turned the world purple.
Once cells had retinal, their internal chemistry would change depending on whether they were exposed to light. This allowed cells to adapt their behavior based on the presence or absence of light.
Fast forward to multicellular life. Organisms could save energy by having cells express only the proteins they needed for their specific functions. The PAX genes allowed for specialization of cells based on their location, and clusters of photosensitive cells evolved into the first eye spots. If an animal had two eye spots on different sides of its body, it could tell the direction of light, helping it orient which way was up.
Over time, eye spots became cup-shaped, allowing them to distinguish light from more directions. The deeper the cup, the better it could do this. Eventually, the cups closed over at the top, turning into pinhole cameras with images projected onto a layer of photoreceptors at the back. Organisms like nautiluses can see blurry images with eyes like these.
Finally, lenses made of clear proteins with different refractive indices came along. Selective pressure favored organisms that could see better, pushing for the development of lenses—specifically, lenses shaped to focus light more precisely onto the retina.
So that's how eyes evolved for the first time—through steady selective pressure stacking small adaptations, one after the other, all the way from basic photosynthesis to the human eye.
Reality doesn't need to sound plausible to be true, but it usually does end up making sense once you understand the driving mechanisms.
Except quantum physics, or so I am told!
More options
Context Copy link
Interesting, thanks for the explanation.
More options
Context Copy link
More options
Context Copy link