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Author Topic:   Human Evolution
CosmicAtheist
Member (Idle past 2388 days)
Posts: 31
From: Washington, USA
Joined: 04-07-2010


Message 1 of 102 (556214)
04-18-2010 4:56 AM


As someone who has dabbled into evolution for sometime I am now interested in really grasping and understanding the theory even better so I will bring up another topic of interest. Specifically: human evolution.

I just have a few brief and simplistic questions to start, forgive me if they seem silly:

1. Why are all other Homo's in the Genus (except us) extinct?

2. As we continue to evolve will there eventually be another speciation event where a group of humans become too genetically incompatible with another? Or since we are so great in number and widespread is this no longer possible?

3. Regarding human origin and ancestry specifically the relation of Humans and Neanderthals: what common ancestor do we share with them? And how long ago was the split?

I have searched the internet regarding these various random questions but I was just curious if anyone here with experience in relevant fields could help me understand further. I know these are completely random questions heh.

Thanks.


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Admin
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Message 2 of 102 (556231)
04-18-2010 8:53 AM


Thread Copied from Proposed New Topics Forum
Thread copied here from the Human Evolution thread in the Proposed New Topics forum.
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DC85
Member (Idle past 3 days)
Posts: 855
From: Richmond, Virginia USA
Joined: 05-06-2003


Message 3 of 102 (556257)
04-18-2010 3:32 PM
Reply to: Message 1 by CosmicAtheist
04-18-2010 4:56 AM


1. Why are all other Homo's in the Genus (except us) extinct?
Because they either were out competed or were unable to adapt to the environment..

2. As we continue to evolve will there eventually be another speciation event where a group of humans become too genetically incompatible with another? Or since we are so great in number and widespread is this no longer possible?
Although I'm sure we can debate this. I honestly don't see humans evolving all that much over time. We adapt or environments to us instead of falling victim to it like other species. The only force I see still at work is sexual selection and even then most humans still will have a chance to reproduce...

3. Regarding human origin and ancestry specifically the relation of Humans and Neanderthals: what common ancestor do we share with them? And how long ago was the split?

Somewhere around 600'000-500'000 years ago and I've read it was Homo rhodesiensis
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DrJones*
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Message 4 of 102 (556259)
04-18-2010 3:34 PM
Reply to: Message 1 by CosmicAtheist
04-18-2010 4:56 AM


As we continue to evolve will there eventually be another speciation event where a group of humans become too genetically incompatible with another?

It might have already happened. Can we be sure that the average H. sapiens of 2010 is interfertile with the average H. sapiens of 1510?


It's not enough to bash in heads, you've got to bash in minds
soon I discovered that this rock thing was true
Jerry Lee Lewis was the devil
Jesus was an architect previous to his career as a prophet
All of a sudden i found myself in love with the world
And so there was only one thing I could do
Was ding a ding dang my dang along ling long - Jesus Built my Hotrod Ministry

Live every week like it's Shark Week! - Tracey Jordan
Just a monkey in a long line of kings. - Matthew Good
If "elitist" just means "not the dumbest motherfucker in the room", I'll be an elitist! - Get Your War On
*not an actual doctor
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Taz
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Posts: 5069
From: Zerus
Joined: 07-18-2006


Message 5 of 102 (556261)
04-18-2010 4:07 PM
Reply to: Message 3 by DC85
04-18-2010 3:32 PM


DC85 writes:

Although I'm sure we can debate this. I honestly don't see humans evolving all that much over time. We adapt or environments to us instead of falling victim to it like other species. The only force I see still at work is sexual selection and even then most humans still will have a chance to reproduce...


I would argue that human evolution has happened in the past, is continuing to happen, and will continue to happen in the future. Natural selection, sexual selection, and the various pressures are only some mechanisms involved in the overall process of evolution. Just by having a population living in an environment, no matter how stable, evolution will happen. The mere fact that mutation is inevitable makes evolution inevitable.
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Coyote
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Message 6 of 102 (556289)
04-18-2010 7:30 PM


Speciation
The easiest way to get speciation is physical separation and different environments.

Nothing I can imagine will do this better than space colonization at distances that permit only limited contact with Earth.


Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.
  
caffeine
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Message 7 of 102 (556366)
04-19-2010 11:45 AM
Reply to: Message 4 by DrJones*
04-18-2010 3:34 PM


It might have already happened. Can we be sure that the average H. sapiens of 2010 is interfertile with the average H. sapiens of 1510?

Yes. As evidenced by the last 500 years of mass migration around the globe, human populations that had been separated for thousands of years are still quite interfertile with one another.


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misha
Member (Idle past 2125 days)
Posts: 69
From: Atlanta
Joined: 02-04-2010


Message 8 of 102 (556566)
04-20-2010 11:41 AM
Reply to: Message 3 by DC85
04-18-2010 3:32 PM


Although I'm sure we can debate this. I honestly don't see humans evolving all that much over time. We adapt or environments to us instead of falling victim to it like other species. The only force I see still at work is sexual selection and even then most humans still will have a chance to reproduce...

I agree. Globalization, modern medicine and agriculture have greatly decreased the selective pressures remaining on the human race.

It is estimated that 1.3% of children in the US will die before the age of 20.

http://www.childtrendsdatabank.org/alphalist?q=node/84

I believe this to be a good estimate of the number of offspring who will reach the age of reproduction. With the numbers this high I see it unlikely that there is enough selective pressure to cause enough evolution resulting in a speciation event.

Compare this to Chimpanzees of whom only 60% reach the age of 7; where the reproductive age is between 7 and 15.

http://www.unl.edu/rhames/chimprs/chimprs.htm

There would really need to be a mass pressure event or isolation in order to quell the mixing of human populations worldwide. Globalization has most likely also contributed to the mixing of human DNA across the globe. I see it unlikely that a human speciation even resulting in 2 distinct species would occur without a great increase in selective pressure.


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CosmicChimp
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Posts: 305
From: Muenchen Bayern Deutschland
Joined: 06-15-2007


Message 9 of 102 (556685)
04-20-2010 6:27 PM
Reply to: Message 1 by CosmicAtheist
04-18-2010 4:56 AM


Hi CosmicAtheist,
1. Why are all other Homo's in the Genus (except us) extinct?
I don't see any greater significance to the situation that three of four known hominid species have gone extinct in recent geologic history, than they could not survive in their environment. The fourth may be on its way to extinction as well in the same geologic time frame and possibly due to the same environmental influence; that being cultural.

2. As we continue to evolve will there eventually be another speciation event where a group of humans become too genetically incompatible with another? Or since we are so great in number and widespread is this no longer possible?
If humans were not so rapidly changed and influenced by our 'big brains' (Kurt Vonnegut's motif in Galápagos: A Novel) then I would say yes, there would come about evolutionary change to people. But, because symbolism and language has sprung up among humans, I too see as many others before me, that our genes are operating now within a larger framework of cultural change far more influential upon our future than anything else that genes or selection could cause.

I was just reading the Wiki article on technological singularity. If you read it I think you might come to the same conclusions as so many others have about human evolution. Genes play a far less significant role in human development as memes play(ed).

I don't know off the top of my head about your third point, but it must be an easy thing to find out. Did you know that a complete Neanderthal genome has been sequenced?

Edited by CosmicChimp, : fixed title


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CosmicAtheist
Member (Idle past 2388 days)
Posts: 31
From: Washington, USA
Joined: 04-07-2010


Message 10 of 102 (556694)
04-20-2010 7:10 PM


Thank you all for the responses so far they have been very informative and CosmicChimp, my 2nd question was the one I was the most curious about, thank you for the article. I skimmed it and when I have more time later tonight I will read it more in depth.
  
barbara
Member (Idle past 2299 days)
Posts: 167
Joined: 07-19-2010


(1)
Message 11 of 102 (571583)
08-01-2010 11:32 AM
Reply to: Message 2 by Admin
04-18-2010 8:53 AM


Re: Thread Copied from Proposed New Topics Forum
It is obvious that many of us do not fully understand evolution. Please correct me if I am wrong.

Evolution is descent with modification (Life can only come from life) and nature never has to start from scratch again right? Is this the correct interpretation in a nutshell? I realize that there is several factors involved in this process.
If true then the fact that I am here living right now, my ancestry goes back before I was classified as Human all the way back to the beginning of the first life on this planet. My line of descent would have many different names to describe who my ancestors were at any particular time frame in history. Humans evolved from many different lines of classification of humans, primates, and before that no one really knows due to lack of fossil evidence.
In other words the only way for me being alive today is because every generation in history lived long enough to produce the next generation that goes back to its origin.


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jar
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Posts: 29183
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Joined: 04-20-2004
Member Rating: 2.8


Message 12 of 102 (571588)
08-01-2010 12:03 PM
Reply to: Message 11 by barbara
08-01-2010 11:32 AM


Re: Thread Copied from Proposed New Topics Forum
Actually almost right. Pretty good as a matter of fact.

barbara writes:

Evolution is descent with modification (Life can only come from life) and nature never has to start from scratch again right?

It's possible, even likely, that life started several times, maybe even many times. It's also possible, likely even, that life could begin again, even today, BUT, unlike that time long, long ago, now there is other life forms that are occupying all those niches and would simply see any new life forms as food.

The earlier attempts had a chance, they did not have to face being eaten by the billions and billions of hungry critters that are out there now.

barbara writes:

If true then the fact that I am here living right now, my ancestry goes back before I was classified as Human all the way back to the beginning of the first life on this planet.

Yup.

barbara writes:

My line of descent would have many different names to describe who my ancestors were at any particular time frame in history. Humans evolved from many different lines of classification of humans, primates, and before that no one really knows due to lack of fossil evidence.

Almost. We don't know all the specifics but actually have a fair idea of the lineage and are learning more every day.

barbara writes:

In other words the only way for me being alive today is because every generation in history lived long enough to produce the next generation that goes back to its origin.

Yup. Every line that did not reproduce became a dead end.


Anyone so limited that they can only spell a word one way is severely handicapped!
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barbara
Member (Idle past 2299 days)
Posts: 167
Joined: 07-19-2010


Message 13 of 102 (571596)
08-01-2010 1:37 PM
Reply to: Message 12 by jar
08-01-2010 12:03 PM


Re: Thread Copied from Proposed New Topics Forum
Thank you for not making me feel stupid and answering my question in a direct manner.

Now that we have established that my whole line of descent is firmly rooted in the tree of life's origin, would my DNA support this? Or through its course in history the genes used in the beginning have been deleted or changed for modification as time moved on so it would not be a reliable source?


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Theodoric
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Posts: 5765
From: Northwest, WI, USA
Joined: 08-15-2005


Message 14 of 102 (571598)
08-01-2010 1:40 PM
Reply to: Message 13 by barbara
08-01-2010 1:37 PM


Source of what?
Or through its course in history the genes used in the beginning have been deleted or changed for modification as time moved on so it would not be a reliable source?

Not sure what you are asking here. Reliable source of what?


Facts don't lie or have an agenda. Facts are just facts
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jar
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Posts: 29183
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.8


Message 15 of 102 (571603)
08-01-2010 1:52 PM
Reply to: Message 13 by barbara
08-01-2010 1:37 PM


Re: Thread Copied from Proposed New Topics Forum
barbara writes:

Now that we have established that my whole line of descent is firmly rooted in the tree of life's origin, would my DNA support this?

It certainly confirms parts of the direct descent idea.

Remember, our knowledge of DNA is just beginning, we still have a long way to go.

BUT, the important thing is that until we got some detailed specs on our DNA, the connection even between humans and all the other primates was based on morphological inference.

What we are learning from DNA is simply another independent confirmation of the Theory of Evolution and Common descent. It's that additional confirmation, one from yet another whole different area of knowledge and methodology, that simply added even more weight to the Theory of Evolution.

barbara writes:

Or through its course in history the genes used in the beginning have been deleted or changed for modification as time moved on so it would not be a reliable source?

Not sure what you are asking there. Do we have examples of the first DNA? No, of course not.

Will comparisons between DNA from different critters and plants help us understand our lineage? Certainly.


Anyone so limited that they can only spell a word one way is severely handicapped!
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