(Lack of) Human Evolution.

Sljslj · 05-30-2010, 01:33 PM

It seems to me that humans just don't evolve physically anymore (mentally maybe, possibly even "devolving" mentally at this point). I have a feeling if you were to hop in your time machine (you can borrow mine if you don't have your own) and travel 40,000 years into the past, you would encounter beings physically identical or nearly so.
So is our understanding of evolution completely off? Or is it that we have no need to evolve anymore? If the latter is true, what might bring us to the point that evolution is once again necessary?
It's an interesting thought and I just wanted to see what the great mind at MB (all three of them) have to say about it.

Guybrush · 05-30-2010, 01:36 PM

Quote:

Originally Posted by Sljslj

So is our understanding of evolution completely off?

No offense, but I think yours might be - at least slightly! As a biology student, I see no real mystery here and I think the notion that there is or the idea that humans have stopped evolving stems from misconceptions about evolution.

What is evolution? What is it you think drives evolution? Who do well in evolution and who get weeded out and why? Some kind of answers to those questions will solve much of the mystery.

Sljslj · 05-30-2010, 01:58 PM

I don't claim to be an expert, but I'm pretty sure I understand natural selection. Is the reason that people haven't changed genetically because we have no need to?; because we have been the heirarchy species for a long time and "survival of the fittest" is no longer applicable? Or am I once again off?
I don't mean to avoid your questions, tore, but I honestly don't know how to answer them without sounding like an idiot or a ****.

Barnard17 · 05-30-2010, 02:11 PM

Out of curiosity, how fast do you think evolution actually happens?

Guybrush · 05-30-2010, 02:19 PM

Well, defining evolution is a bit hard but it's obviously an important thing to do if you want to say whether it happens or not. A lot of ecologists for example might say that evolution is a change in allele frequencies from one generation to the next. For humans, this happens for every new generation so then it's a question of how much. I understand however that you think that humans are not changing as quickly physically as we used to and then I guess you would have to compare. Do you know if we have evolved slower physically the last 100 000 years than we did the 100 000 years before that? You are also focusing on morphological and mental traits, but what about all those genes that you can't really tell that easily?

Evolution is a process of cause and consequence where those who are fittest - those who pass on their genes the most - add more to the human genetic makeup for the future and those who don't pass on their genes, well .. they don't! There are many ways to be fit, but to put it into some kind of perspective, I can make a simple example :

Imagine that there's a plague which kills people, for example cholera. The chances of dying from cholera is quite high, but if you have a specific genetic mutation, your chances of survival are much higher. The reason is the mutation causes a slight change in some ion pumps in your stomach cells which normally just renders these stomach cells less effective and people who have this mutation have more irritable bowels. However, when they are infected with cholera, the same mutation protects them somewhat from the harmful effects of the cholera bacteria which also have an effect on the operation of these ion pumps.

Before cholera occurs, most people don't have the mutation because having it has a slight negative effect on fitness. Diarreah doesn't make people pass on their genes more successfully after all .. But after cholera has occurred, people who had this mutation were much more likely to survive and then the mutation did add to their fitness and did make it much more likely for them to pass on their genes. The occurrence of the mutation after cholera has taken place in the human population is much higher than it was before. The genetics of the human population have changed somewhat and now they are more cholera resistant on the whole than they used to be - there's been some evolution taking place. Because the mutation is not beneficial in a cholera free environment, the frequency of that mutation might change again in the future until it's as rare as it was before the first cholera plague.

The example should be reasonably simple to understand. For a while, there's one selection pressure (cholera) which favours one trait (a mutation). When that pressure is gone, the trait is not favoured anymore. The point is that evolution of specific traits and most likely the sort of changes you are talking about happens as a response to selective pressure. What the pressure is and how strong it is varies with where you are in the world, what your situation is. Different genetic makeups do well in different environments, for different sexual preferences, diseases and so on. Evolution is just a consequence of natural selection. It doesn't stop when it's reached some sort of goal!

~~bungalow~~ · 05-30-2010, 05:25 PM

evolution is a constant process, it doesn't just shut on and off.

Sljslj · 05-30-2010, 06:18 PM

But isn't it possible that if a species reaches some sort of harmony with their environment and the environment itself doesn't undergo any major changes, that mutations aren't necessary, nor beneficial? That seems to be where we're at right now. Also, for the first time, a species is able to create things to meet our needs rather than having to physically adapt to them. For example, instead of fur to keep us warm, we make clothes. Instead of having to actually physically catch our food, we can grow our food or use weapons to kill other animals. Am I making any sense or am I just making an ass of myself?

Burning Down · 05-30-2010, 07:03 PM

Quote:

Originally Posted by Sljslj

But isn't it possible that if a species reaches some sort of harmony with their environment and the environment itself doesn't undergo any major changes, that mutations aren't necessary, nor beneficial? That seems to be where we're at right now. Also, for the first time, a species is able to create things to meet our needs rather than having to physically adapt to them. For example, instead of fur to keep us warm, we make clothes. Instead of having to actually physically catch our food, we can grow our food or use weapons to kill other animals. Am I making any sense or am I just making an ass of myself?

That could be, but not for humans. Our environment is changing - global warming. We need to become climatized to changing temperatures and weather patterns in order to survive. That in itself is a form of evolution. Therefore, the evolution process is still underway.

Sljslj · 05-30-2010, 07:12 PM

Quote:

Originally Posted by Burning Down

That could be, but not for humans. Our environment is changing - global warming. We need to become climatized to changing temperatures and weather patterns in order to survive. That in itself is a form of evolution. Therefore, the evolution process is still underway.

Touché. I guess I rest my case for now.
Though if anyone has anything to add, feel free to do so.

duga · 05-30-2010, 09:11 PM

One thing I find very interesting is that our self awareness evolved from a time when we did strike a harmonious balance with the environment. Food was plentiful and there were no major environmental stresses. This gave us the opportunity to relax in a way and "ponder existence". This lead to self awareness as we know it.

This sort of thing couldn't be expanded on today because of the intense amount of stress that is placed on all of us with jobs, money, and personal issues. However, if we were to find that harmony again, imagine what we could do with our minds at that point.

05-30-2010, 01:33 PM	#1 (permalink)
Sljslj The Omniscient Join Date: Mar 2010 Location: Reno, Nevada, USA Posts: 998	(Lack of) Human Evolution. It seems to me that humans just don't evolve physically anymore (mentally maybe, possibly even "devolving" mentally at this point). I have a feeling if you were to hop in your time machine (you can borrow mine if you don't have your own) and travel 40,000 years into the past, you would encounter beings physically identical or nearly so. So is our understanding of evolution completely off? Or is it that we have no need to evolve anymore? If the latter is true, what might bring us to the point that evolution is once again necessary? It's an interesting thought and I just wanted to see what the great mind at MB (all three of them) have to say about it.

05-30-2010, 02:11 PM	#4 (permalink)
Barnard17 My home? Discabled, Join Date: Jun 2005 Location: Bristol, UK Posts: 204	Out of curiosity, how fast do you think evolution actually happens? __________________ Vita brevis, Occasio praeceps

05-30-2010, 02:19 PM	#5 (permalink)
Guybrush Juicious Maximus III Join Date: Nov 2008 Location: Scabb Island Posts: 6,525	Well, defining evolution is a bit hard but it's obviously an important thing to do if you want to say whether it happens or not. A lot of ecologists for example might say that evolution is a change in allele frequencies from one generation to the next. For humans, this happens for every new generation so then it's a question of how much. I understand however that you think that humans are not changing as quickly physically as we used to and then I guess you would have to compare. Do you know if we have evolved slower physically the last 100 000 years than we did the 100 000 years before that? You are also focusing on morphological and mental traits, but what about all those genes that you can't really tell that easily? Evolution is a process of cause and consequence where those who are fittest - those who pass on their genes the most - add more to the human genetic makeup for the future and those who don't pass on their genes, well .. they don't! There are many ways to be fit, but to put it into some kind of perspective, I can make a simple example : Imagine that there's a plague which kills people, for example cholera. The chances of dying from cholera is quite high, but if you have a specific genetic mutation, your chances of survival are much higher. The reason is the mutation causes a slight change in some ion pumps in your stomach cells which normally just renders these stomach cells less effective and people who have this mutation have more irritable bowels. However, when they are infected with cholera, the same mutation protects them somewhat from the harmful effects of the cholera bacteria which also have an effect on the operation of these ion pumps. Before cholera occurs, most people don't have the mutation because having it has a slight negative effect on fitness. Diarreah doesn't make people pass on their genes more successfully after all .. But after cholera has occurred, people who had this mutation were much more likely to survive and then the mutation did add to their fitness and did make it much more likely for them to pass on their genes. The occurrence of the mutation after cholera has taken place in the human population is much higher than it was before. The genetics of the human population have changed somewhat and now they are more cholera resistant on the whole than they used to be - there's been some evolution taking place. Because the mutation is not beneficial in a cholera free environment, the frequency of that mutation might change again in the future until it's as rare as it was before the first cholera plague. The example should be reasonably simple to understand. For a while, there's one selection pressure (cholera) which favours one trait (a mutation). When that pressure is gone, the trait is not favoured anymore. The point is that evolution of specific traits and most likely the sort of changes you are talking about happens as a response to selective pressure. What the pressure is and how strong it is varies with where you are in the world, what your situation is. Different genetic makeups do well in different environments, for different sexual preferences, diseases and so on. Evolution is just a consequence of natural selection. It doesn't stop when it's reached some sort of goal! __________________ Something Completely Different

05-30-2010, 09:11 PM	#10 (permalink)
duga MB quadrant's JM Vincent Join Date: Dec 2009 Location: Washington, DC Posts: 3,762	One thing I find very interesting is that our self awareness evolved from a time when we did strike a harmonious balance with the environment. Food was plentiful and there were no major environmental stresses. This gave us the opportunity to relax in a way and "ponder existence". This lead to self awareness as we know it. This sort of thing couldn't be expanded on today because of the intense amount of stress that is placed on all of us with jobs, money, and personal issues. However, if we were to find that harmony again, imagine what we could do with our minds at that point. __________________ Confusion will be my epitaph...

05-30-2010, 01:58 PM	#3 (permalink)
Sljslj The Omniscient Join Date: Mar 2010 Location: Reno, Nevada, USA Posts: 998	I don't claim to be an expert, but I'm pretty sure I understand natural selection. Is the reason that people haven't changed genetically because we have no need to?; because we have been the heirarchy species for a long time and "survival of the fittest" is no longer applicable? Or am I once again off? I don't mean to avoid your questions, tore, but I honestly don't know how to answer them without sounding like an idiot or a ****.

05-30-2010, 05:25 PM	#6 (permalink)
~~bungalow~~ Account Disabled Join Date: Oct 2005 Location: Hot-lanta Posts: 3,140	evolution is a constant process, it doesn't just shut on and off.

05-30-2010, 06:18 PM	#7 (permalink)
Sljslj The Omniscient Join Date: Mar 2010 Location: Reno, Nevada, USA Posts: 998	But isn't it possible that if a species reaches some sort of harmony with their environment and the environment itself doesn't undergo any major changes, that mutations aren't necessary, nor beneficial? That seems to be where we're at right now. Also, for the first time, a species is able to create things to meet our needs rather than having to physically adapt to them. For example, instead of fur to keep us warm, we make clothes. Instead of having to actually physically catch our food, we can grow our food or use weapons to kill other animals. Am I making any sense or am I just making an ass of myself?