Real life thread

[solarz]

It's called nictitating membrane. It is usually translucent and moves horizontally to cover one's eyes when needed (assuming you have one, of course).

I hate the idea that, evolutionarily "you lose it if you don't use it". That is simply wrong. Sadly, too many professionals still tend to think that way. Evolution only happens when there is pressure for it. For instance, hypothetically, 1% of human has wings. These people will slowly die off and at best stay as minority if nothing happens. If all of a sudden, a global flood occurs. The only way to stay alive is to fly away. Then these winged humans suddenly become advantageous. While most "normal" human drown, these winged human survive and have offsprings. Then before long, all human on Earth have wings. And you have evolution.

So the nictitating membrane must be disadvantageous for land animals or mammals. This should be why most mammals lost it. Not because it is useless. If it is useless, there would not be any pressure one way or another. Mammals would have kept it.

Any difference you see between human and any other animals should be caused by some functional advantages with how human ancestors behaved and lived back when human first evolved. These features may not be advantageous now because we don't have the same environment that our ancestors had back in the day.

So with the narrow eye lids mentioned by that doctor, that will never happen. There never be any evolutionary pressure to favor such physiology.

Evolution always always goes hand in hand with global disasters, the kind that will make a species extinct. Always! Without such disaster when we just go about our everyday life, evolution will never happen.

I think the "you lose it if you don't use it" idea is a simplification of a more complex idea, but it still makes sense because some traits, just by existing, have a detrimental effect to reproduction. Even if that cost is very small, over millions of years it will be bred out.

Take for example the human tail. There was clearly an evolutionary pressure for humans to not have a tail, however small it might be. There doesn't seem to be a physical reason for it. Having a tiny tail doesn't make you run slower, for example. However, there could have been social pressures: other humans didn't want to mate with a person with a tail, and thus the tail slowly died out.

Typically, traits that really don't matter to survival stay around, such as the different shades of hair color, or having double eyelids, etc.

 

[vesicles]

I think the "you lose it if you don't use it" idea is a simplification of a more complex idea, but it still makes sense because some traits, just by existing, have a detrimental effect to reproduction. Even if that cost is very small, over millions of years it will be bred out.

No, it's not a simplification. It is wrong. The idea of "you lose it if you don't use it" goes completely against the very definition of evolution. It suggests that evolution occurs continuously and without pressure. And somehow the species can change their physiology continuously. This is very commonly mentioned in popular culture. Many speculate what would happen to human body 1 million years from now. I would say absolutely nothing if we are lucky (that is assuming nothing disastrous will happen). IF something happens, we would most likely extinct and something else, which should have a very distinct physiology than ours, will take our place. Why the distinction? Anything that share similar physiology with us might be extinct with us. If we can't survive, how can anything else with similar features with us? It has to be something completely different.

Take for example the human tail. There was clearly an evolutionary pressure for humans to not have a tail, however small it might be. There doesn't seem to be a physical reason for it. Having a tiny tail doesn't make you run slower, for example. However, there could have been social pressures: other humans didn't want to mate with a person with a tail, and thus the tail slowly died out.

There is no physical reason for losing the tail NOW. It doesn't mean there wasn't one back when our ancestors first evolved. Human is not the only mammal without a tail. Many primates, such as chimps, also do not have tails. There must be some selection factor. We don't know about it, yet.

About running, it has never been about the speed for human. It is about endurance. Human is one of the few, if not the only one, that can run and finish a marathon. Human ancestors used endurance to hunt. They simply kept chasing their prey and forcing them to keep running to the point of overheating their brain. so speed is never the issue. Our body is a perfect fit for endurance. One huge evidence of that is that we have sweat glands all over our body. Most other mammals do not. And we don't have fur while most mammals do.

Also, our primate ancestors had already lost their tail, way before the appearance of homosapien. If you want to find out how we lost the tail, you'll have to look at chimps and other primates.

Another thing is that you cannot simply look at a tail on its own. Genetically speaking, many genetic traits are connected. For instance, people with freckles typically have red hair. Many seemingly unrelated genes are located on the same chromosome. So if you lose one trait, you might lose something that might be completely different. Hypothetically, the tail gene might be connected to thick fur. So those early humans who happened to be excellent runners and good hunters had less body hair and also no tail. It might not be the tail that was under the evolutionary pressure at all. It was the thick fur. But because tail and fur genes happened to be located next to each other, you would have to lose both all together. This is all hypothetical, of course.

Typically, traits that really don't matter to survival stay around, such as the different shades of hair color, or having double eyelids, etc.

That's exactly my point. you can't lose simply because you don't use it. There has to be evolutionary pressure to select, one way or another.

 

[solarz]

No, it's not a simplification. It is wrong. The idea of "you lose it if you don't use it" goes completely against the very definition of evolution. It suggests that evolution occurs continuously and without pressure. And somehow the species can change their physiology continuously. This is very commonly mentioned in popular culture. Many speculate what would happen to human body 1 million years from now. I would say absolutely nothing if we are lucky (that is assuming nothing disastrous will happen). IF something happens, we would most likely extinct and something else, which should have a very distinct physiology than ours, will take our place. Why the distinction? Anything that share similar physiology with us might be extinct with us. If we can't survive, how can anything else with similar features with us? It has to be something completely different.

That's exactly my point. you can't lose simply because you don't use it. There has to be evolutionary pressure to select, one way or another.

I don't think that expression discounts the role of selection pressure in evolution. Instead, I think it assumes that all species are constantly experiencing various selection pressures.

First, there is sexual selection, which plays a pretty big part in evolution. Traits that do not help with survival are nonetheless promoted through sexual selection, such as the tail feathers of the male peacock.

Second, on an evolutionary scale, the Earth is constantly changing, thus constantly forcing species to evolve and adapt.

So to take your example of 1 million years in the future, assuming the human race is still around (very doubtful), it would be a practical impossibility that some kind of environmental change has not caused our bodies to evolve and adapt. After all, geologists have just announced we have entered a new geological epoch, so it's pretty unlikely that there won't be big environmental changes in 1 million years.

Furthermore, evolutionary traits do not have to be drastic to make a big difference. For example, something as simple as a species of zooanthellae being more tolerant of acidic water would allow corals to survive climate change.

 

[siegecrossbow]

First, there is sexual selection, which plays a pretty big part in evolution. Traits that do not help with survival are nonetheless promoted through sexual selection, such as the tail feathers of the male peacock.

I always thought that if a male peacock could sport such an outlandishly long and heavy without getting eaten, it must be fit and healthy enough to pass on good genes.

 

[vesicles]

I don't think that expression discounts the role of selection pressure in evolution. Instead, I think it assumes that all species are constantly experiencing various selection pressures.

First, there is sexual selection, which plays a pretty big part in evolution. Traits that do not help with survival are nonetheless promoted through sexual selection, such as the tail feathers of the male peacock.

Second, on an evolutionary scale, the Earth is constantly changing, thus constantly forcing species to evolve and adapt.

So to take your example of 1 million years in the future, assuming the human race is still around (very doubtful), it would be a practical impossibility that some kind of environmental change has not caused our bodies to evolve and adapt. After all, geologists have just announced we have entered a new geological epoch, so it's pretty unlikely that there won't be big environmental changes in 1 million years.

Furthermore, evolutionary traits do not have to be drastic to make a big difference. For example, something as simple as a species of zooanthellae being more tolerant of acidic water would allow corals to survive climate change.

I think you are confusing macroscopic features with genetic evolution. The issue at hands is that the scale of evolution. When you see a change in small feature of an animal without any global change (your example of zooanthellae adapting to acidic water), you assume that this change must have come gradually. My question is: how does the new feature become dominant in a species? It is impossible for 50% of individuals within a single species to make the same mutation all at the same time. So how does that 0.001% of the species with the mutation to take over and become dominant enough to define evolution of an entire species?

Let's use your example of zooanthellae becoming more tolerant of acidic water. What you can see on a macroscopic level, you don't see much change with the overall physiology of the zooanthellae when they become adaptable to acidic water and assume that these organisms simply gradually changed their physiology to adapt. Then the same question: how did that 0.001% of zooanthellae with mutation to adapt acidic water become dominant?

In reality, something much more drastic has happened to zooanthellae. At the beginning, majority of the zooanthellae would not tolerate acidic water well, while a tiny fraction possesses some mutated genes that allow them to tolerate acidity. If ocean water stays as normal, this small fraction would die off quickly. As ocean water becomes acidic, this small fraction of zooanthellae can survive much better. Yes, but even at its very best, this would only allow such small fraction of acidic water-adaptable zooanthellae to maintain its population, hence maintaining its 0.001%. However, the majority of the zooanthellae would still be prone to acidic water. The only way for this small fraction of zooanthellae to become dominant, i.e. the only way that we human can notice such change in zooanthellae behavior, is that vast majority of the "normal" zooanthellae die off. This would leave only those acidity-adaptable zooanthellae, thus changing zooanthellae genetic make-up, thus evolution. Mathematically speaking, that is the ONLY way evolution can occur. The majority of the dominant feature must die off in order for the new feature to become dominant enough to qualify as evolution.

You will not see this drastic dying off macroscopically because the mutant will most likely still look the same as the original and you assume that nothing dramatic has happened. Yet, to the zooanthellae, it's almost like a global disaster.

The same concept applies to every living thing. The initial batch of individuals with a unique mutation is always small, infinitely small, in population because all mutations are random with no exception. One in a million, one in a billion, etc. For such mutants to become dominant, something drastic must happen. The majority must go away. Without anything drastic, the best the random mutants can hope for is to maintain its infinitely small population. No doubt about it.

 

[vesicles]

Let's do some math! We all know the exponential growth equation: N(t) = N(0) x exp(rt).

Let's assume we have an initial population of 10,000. Within it, 10 individuals have a unique genetic mutation (mutant %: 0.1%). To maximize their chance of keeping the gene alive, we will do inbreeding among the 10 individuals and maintain purity of the mutant gene. and let's assume that this species has an annual growth rate of 10%. After 100 years, we will get 220,264,658 normal individuals and 220,265 mutants, still exactly 0.1%. As you can see, even in the best case scenario, you can only maintain your mutant population. In reality, your mutant gene will be lost in the ocean of wild-type genes in no time as there is no way to maintain purity of a genetic make-up in the wild. And majority of the mutations is typically recessive, meaning that the chance of having both copies of the mutant gene in the same body is even less. It's completely hopeless to hope that your mutant can gradually become dominant species... It's mathematically impossible even under the most ideal conditions.

 

[Jeff Head]

This is one of the model kits I bought, which is die cast and pretty muich already built...you screw them together. I put together a couple of YouTube videos showing it.

I made a few changes.

SkyPilot SH-60 Sehawk Helicopter Pt. 1

SkyPilot SH-60 Sehawk Helicopter Pt. 2

 

[B.I.B.]

Dutch police train eagles to take out drones

 

[Jeff Head]

Thought I'd let everyone know about a new thread I started. It is about a relatively new Naval Wargaminig Simulation I purchased this weekd and it is very good.

Anyone really interested in Naval technology and Warfae should be interested in this simulation, and I figured there would be quite a few on SD. I am in no way connected to the people who developed the game or its publisher/marketing. Just thought SD members may find it interesting.

it is a very worthy successor to the Harpoon gaming system which was used in the 1980s and 1990s to train naval officers..

Here's the thread:

https://www.sinodefenceforum.com/command-modern-air-naval-operations-simulation-game.t7950/

Anyhow, take a look and let me know what you think.

 

[AssassinsMace]

Because I'm not voting for Hillary I was accused recently by an acquaintance that it was because she was a woman. This person has been around me long enough to know why I don't like Hillary and it has nothing to do with her being a woman. And the accusation comes on the heels of Madeline Albright saying there's a special place in Hell for women who don't support a woman meaning Hillary Clinton in light that she's not getting blanket support from women voters especially middle age and younger. Then Gloria Steinem charges young women are only voting for Bernie Sanders because that's who young men are voting for and they just want to be liked. All these dirty tactics and they wonder why Hillary isn't liked? It also doesn't help that Democratic National Committee Chair Debbie Wasserman-Schultz, a Hillary supporter, tried to engineer only a few Democratic Presidential nominee debates because she knew the more Hillary had to talk, the more people don't like her. Yet they're trying push someone not popular down people's throats by even using intimidation and other undemocratic tactics. Ironically I remember when Republican Matt Fong ran against Barbara Boxer for California's US Senate seat, the Democrat establishment was afraid Asian-American Democrats might for him just because he was Asian. That would be their democratic right, wouldn't it? I even heard Democrats call for Asian-Americans to lose their citizenship if they dared. But somehow now it's demanded by the Democratic establishment that women vote for women. BTW, I don't like Bernie Sanders either because like Trump they're both pushing a utopian vision respective of their parties' beliefs that by its own nature is unrealistic. Meaning they're going to fail to live up to their own ideals and turn out just like the establishment they rail against.