Evolution of mammals

ymalmsteen887
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Evolution of mammals

At what point in the evolution of reptiles did they go from laying hard shelled eggs to keeping the egg in the body.

In otherwords how did this happen one generation lays eggs and then the next doesnt that seems kinda strange.

Did it go something like the eggs where getting eaten and the animals that didnt lay eggs reproduced better.


ymalmsteen887
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cj wrote:ymalmsteen887

cj wrote:

ymalmsteen887 wrote:

That makes me think if every male black person only got with a chinese woman and every chinese male only got with a black woman after so many generations wouldnt there no longer be a difference wouldnt they be a single race?

 

There is no such thing as race.  See "The Journey of Man" by Spencer Wells either as a PBS special on dvd or the book.

http://www.amazon.com/s/ref=nb_sb_ss_i_4_32?url=search-alias%3Daps&field-keywords=the+journey+of+man+spencer+wells&x=0&y=0&sprefix...

People have a number of genetic disorders that can cause skin color splotches.  Here is one.  http://ghr.nlm.nih.gov/condition/vitiligo  Browsing the site is sort of interesting - for so called "perfect" creations "made in God's image" humans sure are subject to a lot of genetic disorders.

And again, Wiki is not too awful bad for a resource: http://en.wikipedia.org/wiki/Human_skin_color

 

Is what I brought up about populations seperating what happened to asian people being in different locations so they went in their own direction mutation wise, is this right its not tha there eyes being different actually has a function. Also if I can't call them race waht can I call them?


cj
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ymalmsteen887 wrote: Is what

ymalmsteen887 wrote:

Is what I brought up about populations seperating what happened to asian people being in different locations so they went in their own direction mutation wise, is this right its not tha there eyes being different actually has a function. Also if I can't call them race waht can I call them?

 

Again, from Wiki:

Quote:

The epicanthic fold occurs more frequently among people of North Asian, Central Asian, and East Asian descent, such as the Mongols, Han Chinese, Tibetans, Buryats, Koreans, Japanese, Kazakhs, Hazaras, Kyrgyz, Yakuts and other groups. It is also commonly though less frequently found among Southeast Asians and certain other Asian ethnic groups like Vietnamese, Burmese, Cambodians, Thais, Bhutanese, northern Nepalis, Ladakhis, people (mostly tribal) from Eastern Bangladesh and North Eastern India (for example, the Chakma, Marma, the Sylhetis, the Mizo and the Garo), among others. Mixed race people of partially Asian descent, such as Eurasians and Afro-Asians may inherit epicanthic folds.

Epicanthic folds are also common among Native Americans and Inuit. They can also be found inherited among some Oceanic peoples including Tongans, Samoans, Micronesians and Hawaiians.

A minority of people within some African ethnic groups also have epicanthic folds; these include the Khoisans (Capoids) in Africa and certain groups from southern Sudan such as the Dinka and the Nuer.

Epicanthic folds are also found in a minority of Europeans, especially in eastern Europe and across northern Europe in areas such as Scandinavia and Poland, as well as within Ireland and Britain. One of the existing accounts suggests that Europeans who possess the fold also have less prominent brow ridges.[citation needed]

/quote]

 

Since there isn't a citation, I wouldn't believe all of this without more proof.  But it looks like the eye fold is found around the world with a higher concentration in what we now call Asia.  Which you would expect if it is a random mutation.

What would you call them?  How about humans?  If you are referring to a particular genetic trait, you can say that - people with an eye fold.

 

-- I feel so much better since I stopped trying to believe.

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ymalmsteen887
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cj wrote:ymalmsteen887

cj wrote:

ymalmsteen887 wrote:

Is what I brought up about populations seperating what happened to asian people being in different locations so they went in their own direction mutation wise, is this right its not tha there eyes being different actually has a function. Also if I can't call them race waht can I call them?

 

Again, from Wiki:

Quote:

The epicanthic fold occurs more frequently among people of North Asian, Central Asian, and East Asian descent, such as the Mongols, Han Chinese, Tibetans, Buryats, Koreans, Japanese, Kazakhs, Hazaras, Kyrgyz, Yakuts and other groups. It is also commonly though less frequently found among Southeast Asians and certain other Asian ethnic groups like Vietnamese, Burmese, Cambodians, Thais, Bhutanese, northern Nepalis, Ladakhis, people (mostly tribal) from Eastern Bangladesh and North Eastern India (for example, the Chakma, Marma, the Sylhetis, the Mizo and the Garo), among others. Mixed race people of partially Asian descent, such as Eurasians and Afro-Asians may inherit epicanthic folds.

Epicanthic folds are also common among Native Americans and Inuit. They can also be found inherited among some Oceanic peoples including Tongans, Samoans, Micronesians and Hawaiians.

A minority of people within some African ethnic groups also have epicanthic folds; these include the Khoisans (Capoids) in Africa and certain groups from southern Sudan such as the Dinka and the Nuer.

Epicanthic folds are also found in a minority of Europeans, especially in eastern Europe and across northern Europe in areas such as Scandinavia and Poland, as well as within Ireland and Britain. One of the existing accounts suggests that Europeans who possess the fold also have less prominent brow ridges.[citation needed]

/quote]

 

Since there isn't a citation, I wouldn't believe all of this without more proof.  But it looks like the eye fold is found around the world with a higher concentration in what we now call Asia.  Which you would expect if it is a random mutation.

What would you call them?  How about humans?  If you are referring to a particular genetic trait, you can say that - people with an eye fold.

 

Really you mean I cant say asian people or go even further and say chinese,japanese, and korean?


cj
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ymalmsteen887 wrote:cj

ymalmsteen887 wrote:

cj wrote:

ymalmsteen887 wrote:

Is what I brought up about populations seperating what happened to asian people being in different locations so they went in their own direction mutation wise, is this right its not tha there eyes being different actually has a function. Also if I can't call them race waht can I call them?

 

Again, from Wiki:

Quote:

The epicanthic fold occurs more frequently among people of North Asian, Central Asian, and East Asian descent, such as the Mongols, Han Chinese, Tibetans, Buryats, Koreans, Japanese, Kazakhs, Hazaras, Kyrgyz, Yakuts and other groups. It is also commonly though less frequently found among Southeast Asians and certain other Asian ethnic groups like Vietnamese, Burmese, Cambodians, Thais, Bhutanese, northern Nepalis, Ladakhis, people (mostly tribal) from Eastern Bangladesh and North Eastern India (for example, the Chakma, Marma, the Sylhetis, the Mizo and the Garo), among others. Mixed race people of partially Asian descent, such as Eurasians and Afro-Asians may inherit epicanthic folds.

Epicanthic folds are also common among Native Americans and Inuit. They can also be found inherited among some Oceanic peoples including Tongans, Samoans, Micronesians and Hawaiians.

A minority of people within some African ethnic groups also have epicanthic folds; these include the Khoisans (Capoids) in Africa and certain groups from southern Sudan such as the Dinka and the Nuer.

Epicanthic folds are also found in a minority of Europeans, especially in eastern Europe and across northern Europe in areas such as Scandinavia and Poland, as well as within Ireland and Britain. One of the existing accounts suggests that Europeans who possess the fold also have less prominent brow ridges.[citation needed]

 

Since there isn't a citation, I wouldn't believe all of this without more proof.  But it looks like the eye fold is found around the world with a higher concentration in what we now call Asia.  Which you would expect if it is a random mutation.

What would you call them?  How about humans?  If you are referring to a particular genetic trait, you can say that - people with an eye fold.

 

Really you mean I cant say asian people or go even further and say chinese,japanese, and korean?

 

Those are geographic/national boundaries.  That doesn't bother me, why should it?  You want to refer to "people in Asia" - fine.  "People in Africa" - great.  "Nordic peoples" - why not?

I object to "races" as ALL traits are expressed in all populations.  And "race" has been used as a way to put people down.  It is not accurate and it is hurtful.  Let the word die.

I'm not real happy when filling out a form and it asks - white (caucasian), black, American Indian, etc.  And then some of them go on and ask if you are Hispanic and what nationality - Cuban, Mexican, Puerto Rican, etc.  I will fill it out, but I do wish it wasn't true that "people of this background <make less><have worse health><whatever else>".  Then we quit asking the question because it no longer told us anything.

As it is now, people are classified and treated differently based on physical characteristics they have no control over. 

 

-- I feel so much better since I stopped trying to believe.

"We are entitled to our own opinions. We're not entitled to our own facts"- Al Franken

"If death isn't sweet oblivion, I will be severely disappointed" - Ruth M.


ymalmsteen887
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cj wrote:ymalmsteen887

cj wrote:

ymalmsteen887 wrote:

cj wrote:

ymalmsteen887 wrote:

Is what I brought up about populations seperating what happened to asian people being in different locations so they went in their own direction mutation wise, is this right its not tha there eyes being different actually has a function. Also if I can't call them race waht can I call them?

 

Again, from Wiki:

Quote:

The epicanthic fold occurs more frequently among people of North Asian, Central Asian, and East Asian descent, such as the Mongols, Han Chinese, Tibetans, Buryats, Koreans, Japanese, Kazakhs, Hazaras, Kyrgyz, Yakuts and other groups. It is also commonly though less frequently found among Southeast Asians and certain other Asian ethnic groups like Vietnamese, Burmese, Cambodians, Thais, Bhutanese, northern Nepalis, Ladakhis, people (mostly tribal) from Eastern Bangladesh and North Eastern India (for example, the Chakma, Marma, the Sylhetis, the Mizo and the Garo), among others. Mixed race people of partially Asian descent, such as Eurasians and Afro-Asians may inherit epicanthic folds.

Epicanthic folds are also common among Native Americans and Inuit. They can also be found inherited among some Oceanic peoples including Tongans, Samoans, Micronesians and Hawaiians.

A minority of people within some African ethnic groups also have epicanthic folds; these include the Khoisans (Capoids) in Africa and certain groups from southern Sudan such as the Dinka and the Nuer.

Epicanthic folds are also found in a minority of Europeans, especially in eastern Europe and across northern Europe in areas such as Scandinavia and Poland, as well as within Ireland and Britain. One of the existing accounts suggests that Europeans who possess the fold also have less prominent brow ridges.[citation needed]

 

Since there isn't a citation, I wouldn't believe all of this without more proof.  But it looks like the eye fold is found around the world with a higher concentration in what we now call Asia.  Which you would expect if it is a random mutation.

What would you call them?  How about humans?  If you are referring to a particular genetic trait, you can say that - people with an eye fold.

 

Really you mean I cant say asian people or go even further and say chinese,japanese, and korean?

 

Those are geographic/national boundaries.  That doesn't bother me, why should it?  You want to refer to "people in Asia" - fine.  "People in Africa" - great.  "Nordic peoples" - why not?

I object to "races" as ALL traits are expressed in all populations.  And "race" has been used as a way to put people down.  It is not accurate and it is hurtful.  Let the word die.

I'm not real happy when filling out a form and it asks - white (caucasian), black, American Indian, etc.  And then some of them go on and ask if you are Hispanic and what nationality - Cuban, Mexican, Puerto Rican, etc.  I will fill it out, but I do wish it wasn't true that "people of this background <make less><have worse health><whatever else>".  Then we quit asking the question because it no longer told us anything.

As it is now, people are classified and treated differently based on physical characteristics they have no control over. 

 

I totally agree with you about the race thing but I was talking from a Taxonomy perspective.


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 OK, race is not a term

 

OK, race is not a term which is useful on the level of determining social policies. For that, the matter is balls useless. On the other hand, there are “racial traits” which may have some relevance when any of us are in the doctor's office.

 

As we all know, showing up at the doctor with a certain set of symptoms does not automatically clinch the diagnosis. If that were the case, then doc would not have to order tests to get other useful information.

 

That much being said, there are certain conditions for which race is relevant. One that is of some interest is sickle cell disease. Generally, only those of African descent get it. However, that is not absolute as I will explain.

 

You see, as BobSpence observed, recessive genes generally do not manifest unless an individual has two copies. So those with one copy of a recessive gene are only carriers of the trait. As the gene for sickle cell disease is recessive, it can turn up pretty much in any population. I would have to do some googling on the matter but from what I remember, there are a few individuals with full blown sickle cell disease who come from native Icelandic stock. Because the gene has existed long enough that it has had time to travel there through the slow process of village to village transfer.

 

That being said, it would raise the question of why it would be more common in Africa than elsewhere. Here is the rub: Apparently, the gene (or another one that is closely associated) is dominant for Malaria resistance. So nif you have one copy, you have a better chance of not getting that disease. At least if you live in the tropics.

 

Thus, there is a selection pressure for the gene in Africa, provided that you don't get two copies. In that case, you will not likely live to have kids regardless of the fact that you can survive a bite from a tropical mosquito.

 

On the other hand, the selection pressure in Iceland is different. Since the anopheles mosquito does not live there, getting two copies of the gene is a bad thing but simply having one copy and continuing to pass it on means nothing. So there is no huge pressure for the recessive single gene to die out.

 

One idea that would be worth looking into would be if the disease is showing up in the Hispanic population of South America. After all, the gene is somewhat wide spread and malaria exists there. If the pair of traits is turning up in a population that may retain the gene in single copy individuals and those people have since moved into an area where the gene becomes relevant, then it should reassert itself.

 

Meh, someone else can google for that if they wish.

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