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Speciation among primates and hominids

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Speciation among primates and hominids

Postby Hozefit » Sat Jul 04, 2009 1:33 am

Does anybody know exactly how long it takes for speciation to occur among primates and hominids, especially the shortest timeframe? I've found very little regarding this.
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Re: Speciation among primates and hominids

Postby AFJ » Sat Jul 04, 2009 2:01 am

http://www.boston.com/news/nation/articles/2007/01/24/skeleton_of_earliest_primate_discovered/
Disclaimer: If you don't have a problem with why C-14 would be in rocks that are "dated," by potassium argon and uranium lead at hundreds of millions of years old..then the first primate is set at 56 million years and the first homo sapien at 500,000 to 1million years.
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Re: Speciation among primates and hominids

Postby Hozefit » Sat Jul 04, 2009 1:50 pm

You misunderstood. I'm not asking for how old the first primate is and when humans first appeared. I'm wondering what the shortest timeframe for speciation to occur among primates/hominids is. IE, say, taking 2 hominid/primate species, seperating them entirely for a long period of time, and how long it would take them to speciate.

Also, aren't humans 250,000-200,500 years old?
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Re: Speciation among primates and hominids

Postby AFJ » Sat Jul 04, 2009 3:42 pm

I read an article a while back where they found a skull that pushed it back to 1 m, but you know that has to go through scrutiny. Did anyone else read that? Who knows for sure?

I think it goes back to gamila's issue also--what is a species? Theoretically, couldn't a chimp and another ape cross breed and "speciate." Sorry I just have a problem with the mechanics of the speciation theory, when it comes to the creation of entirely new orders of organisms. I have no problem with speciation within families of organisms. This kind of "speciation" is observable.

If two populations separate, there would have to be a mass simultaneous mutation in the population to root out the originals and create another family or order of organisms. Or EVEN if you have only a male and female who get separated from the pack geographically, think of the process that would ensue in order to produce a new order. If one mutates with a dominant trait, then the recessive trait will still show in the offspring, and as modern mutations would still be around. They would have to keep separating over and over again as if there was an unseen breeder in charge, and then would we have an entirely different phylum one day? At one point an inverbrate started having a useless beginning of a spine that would be rooted out by NS.

There is no way of knowing if this actually happened in the past because present organisms have distinct phenotypical gaps.

Darwin saw closely related organisms isolated but not far from one another. He was able to tell they were related by the similar phenotypes, but there were differences. It is conceivable to believe that these variations could take place by isolation--but these are slight variations within a genus or family.
Last edited by AFJ on Sat Jul 04, 2009 4:56 pm, edited 5 times in total.
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Re: Speciation among primates and hominids

Postby Hozefit » Sat Jul 04, 2009 3:45 pm

Well, on another note, wouldn't it be true that more biologically complex and advanced species' like hominids/primated would take longer to speciate? I think I've heard of species of fish taking only about 10,000 year so to speciate, and I've also heard speciation takes place more quickly in northern climates due to greater selection pressures.
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Re: Speciation among primates and hominids

Postby AFJ » Sat Jul 04, 2009 4:49 pm

i don't know, hozefit. These are all unobserved theories which have no way of being tested, all served up to us as if they were actually operational science.

What are the greater selection pressures in the north? Interesting.

I've always wondered how fish can isolate--it seems that they isolate themselves by instinct i.e. schools, which would further argue against speciation of all species by isolation. On the other hand it would give evidence of Genesis 1 i.e. "let them multiply after their kinds."
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Postby Jesse2504 » Sat Jul 04, 2009 7:37 pm

If speciation is to occur, they must have varying evolutionary advantages that increase the frequency of certain genotypes, even in sympatric isolation, some sort of isolation must be there to create at least two distinct species. The next question is how to define when there are new species, morphologically would be the main way to attempt this as some may still be too similar phylogenetically to be called different species.

Just because there are harsh environmental conditions does not mean speciation chance will increase. Some changes just outright kill any form of the organism while a mild change in environment that is key to the organisms habits would have a greater effect.

Saying that I think in terms of our species we tend to not biologically adapt to anything anymore, more so just use a technological advance to create artificial fitness.

Witnessing an evolutionary change in any primates or hominids would probably not occur in anyone's life time, but scientific documentation might give us direct evidence in years to come, that aren't based on fossils.
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Re:

Postby Hozefit » Sun Jul 05, 2009 5:44 pm

Jesse2504 wrote:If speciation is to occur, they must have varying evolutionary advantages that increase the frequency of certain genotypes, even in sympatric isolation, some sort of isolation must be there to create at least two distinct species. The next question is how to define when there are new species, morphologically would be the main way to attempt this as some may still be too similar phylogenetically to be called different species.


I may not be fully understanding you, but doesn't speciation just come down to genetic distance and distinctiveness?

Just because there are harsh environmental conditions does not mean speciation chance will increase. Some changes just outright kill any form of the organism while a mild change in environment that is key to the organisms habits would have a greater effect.


The study I'm reffering to went by the idea that increased environmental pressures would lower population levels, and thus increase the chance of genetically isolated populations to increase. It's simple, and more complex than that, but apparently a key component.

I just really need an answer to this, if there really is anything out there at the moment. Genetic research will eventually replace the importance of fossil evidence, and from what I can tell, much of the way we've gauged primate/hominid speciation is largely via fossil differences.

I've also heard that, among primates/hominids, it takes on the scale of 1 million years or more for major neurological changes to occur- IE, the ones that seperate humans from h. erectus and neanderthals.

On another note, it is rather urgent that I get something to get an idea of the speed of primate/hominid speciation. It's apart of some important academic work I'm doing. I've seen plenty of charts on the appearance of humans and non-human hominids in the past several years, and studies mentioning their basic "divergence", but none of these really answer just when the populations became truly genetically seperated, and how long it took them to speciate. It seems like alot of the fossil classifications on hominid speciation go by broad skeletal differences, which may not follow the rate of speciation to the letter.
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Re: Re:

Postby Jesse2504 » Sun Jul 05, 2009 7:55 pm

Hozefit wrote:
Jesse2504 wrote:If speciation is to occur, they must have varying evolutionary advantages that increase the frequency of certain genotypes, even in sympatric isolation, some sort of isolation must be there to create at least two distinct species. The next question is how to define when there are new species, morphologically would be the main way to attempt this as some may still be too similar phylogenetically to be called different species.


I may not be fully understanding you, but doesn't speciation just come down to genetic distance and distinctiveness?

Just because there are harsh environmental conditions does not mean speciation chance will increase. Some changes just outright kill any form of the organism while a mild change in environment that is key to the organisms habits would have a greater effect.


The study I'm reffering to went by the idea that increased environmental pressures would lower population levels, and thus increase the chance of genetically isolated populations to increase. It's simple, and more complex than that, but apparently a key component.

I just really need an answer to this, if there really is anything out there at the moment. Genetic research will eventually replace the importance of fossil evidence, and from what I can tell, much of the way we've gauged primate/hominid speciation is largely via fossil differences.

I've also heard that, among primates/hominids, it takes on the scale of 1 million years or more for major neurological changes to occur- IE, the ones that seperate humans from h. erectus and neanderthals.

On another note, it is rather urgent that I get something to get an idea of the speed of primate/hominid speciation. It's apart of some important academic work I'm doing. I've seen plenty of charts on the appearance of humans and non-human hominids in the past several years, and studies mentioning their basic "divergence", but none of these really answer just when the populations became truly genetically seperated, and how long it took them to speciate. It seems like alot of the fossil classifications on hominid speciation go by broad skeletal differences, which may not follow the rate of speciation to the letter.


Speciation can be judged by different means, morphological is basically a matter of "this one looks different to that one", phylogenetical is genetic variance. Two individuals may look different but be genetically similar or the other way around.
I'm not sure if data on such changes even exists yet, you might have to look hard for such information, perhaps speculation may do you for what you seek to achieve, as I'm sure even experts would be hard pressed to give a definitive answer.
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Re: Speciation among primates and hominids

Postby Hozefit » Mon Jul 06, 2009 12:20 am

Well, could you possibly direct me to someone who can? There's obviously data for the speed of speciation on other organisms, so what do you know in those regards? Are they heavily tied to things like neurological complexity?

Like I said, I've heard a number of times that major evolutionary changes in primates/hominids, when it comes to neurological, physiological, and biochemical structures takes on the scale of 1 million years or more, which is why I think speciation wouldn't be too different.

Works dealing with such a topic would be this: http://www.amazon.com/Principles-Brain- ... 429&sr=8-1
http://www.pubmedcentral.nih.gov/articl ... id=1636539
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Postby biohazard » Mon Jul 06, 2009 8:02 am

People should keep in mind that the term 'species' is just a man made way of putting things into categories. Nature hardly cares whether a chihuahua and great dane are same species or not: we label them both dogs, but you can be pretty certain that the two would have hard time having puppies... so it doesn't make evolution void even if us humans cannot exactly define what a species is.

And I know that AFJ keeps telling us that there is something dodgy when it comes to generating whole new orders of species, but only because we have are having difficulties in observing it, it doesn't make the process impossible either.

In general, complex organisms and large organisms that have few offspirng and long life span take longer to speciate. But with dogs and domestic animals, for example, one can clearly see that by breeding one can increase the speed of speciation manyfold. It has taken mere thousands of years to make a dog out of a wolf, for example. So the quickest way to make new species out of primates would probably be selective breeding (at the moment, genetic engineering is likely to speeden up that hugely in the future, if we so choose).
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Re:

Postby Hozefit » Mon Jul 06, 2009 3:40 pm

biohazard wrote:People should keep in mind that the term 'species' is just a man made way of putting things into categories. Nature hardly cares whether a chihuahua and great dane are same species or not: we label them both dogs, but you can be pretty certain that the two would have hard time having puppies... so it doesn't make evolution void even if us humans cannot exactly define what a species is.


Well, they're certainly of the same species, it's just that canids are of a biological extremity compared to humans. The reason for the immense levels of biological diversity you see amongst dogs is due to the fact that canids have incredibly high levels of tandem repeats, which allows them to evolve and biologically change far more quickly than humans do. Their smaller brain sizes and shorter life spans also add to this.

This is obviously possible with humans, such as if an obese or extremely tall person were to breed with a very thin or short person. However, that's far less likely to occur among humans than among dogs.

But that's getting abit topic, I just wanted to clarify. If the known timeframe of primate speciation is so little known among humans, what about other species? Could their speciation be extrapolated to humans?
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