Fossils of possible new human species found in China

[AquaEyes]

I am enjoying following this thread and wonder if anyone has followed the story regarding the cross-breeding between Alaskan Brown Bears and Polar Bears? There have been several killed by hunters which means there are probably many more in the wild. What I am wondering is if the cross- breed bears are sterile, or if they can pass on their genes to another generation? Also, I am wondering if this would be considered "Evolution, Adaptation or Something Else"? I look forward to hearing opinions and statistics regarding this.

The hybrids are not sterile, and an increasing frequency in their occurrence can indicate that the boundaries between the two species are blurring, probably as a result of the arctic warming. Female polar bears must range further inland searching for food, more often encountering brown bears. When a female is in-season, she attracts whatever males are in the area. And if she's increasingly "in the area" of brown bears, her chances of being bred by one will also increase. The hybrid offspring learn their "way of life" by following their mother, and so these hybrids will try to be polar bears. As ice flows melt earlier and form later, and polar bears feed inland for longer periods of time, the more extreme "pure-polar" phenotype may become less of an advantage for living in this changing area than before, and the hybrid offspring can "get by" being only half polar bear. They'll likely breed back into the polar bear population (being raised by a polar bear mother), and over time, brown bear genes will flow back into the polar bear population. This may result in polar bears being different in a few generations than they are now, but if that phenotype is more advantageous in a newly warming arctic, then those "mostly-polar" bears will be selected over "pure-polar" bears. And what you'll have is evolution -- a change in the inherited phenotype frequencies within a population over time.

I'm not aware if the reverse hybridization happens much in the wild -- male polar X female brown. I did read some articles and watch a documentary on the one that was shot a few years back, and genetic analysis showed that its mother was a polar bear. What I gathered from that (and remember in the time since I read them) was that the reverse is rarer or still unknown, but I suppose that they'd likewise follow a "brown-bear" lifestyle. Being as the white coat color seems to be dominant, however, leads me to think that these bears wouldn't do as well among their brown neighbors, and fewer would survive to reproduce.


ETA -- I checked to see what wikipedia had to say about this. See link below.

http://en.wikipedia.org/wiki/Grizzly–polar_bear_hybrid

 

[perchie.girl]

I believe this happens more often than previously thought.

edited to remove my more ignorant parts..... vbg

deb

I am enjoying following this thread and wonder if anyone has followed the story regarding the cross-breeding between Alaskan Brown Bears and Polar Bears? There have been several killed by hunters which means there are probably many more in the wild. What I am wondering is if the cross- breed bears are sterile, or if they can pass on their genes to another generation? Also, I am wondering if this would be considered "Evolution, Adaptation or Something Else"? I look forward to hearing opinions and statistics regarding this.


Quote:

 

[chickened]

Remember that "species" is a man made term and does not necessarily mean that bears are separate as a species.

 

[DCasper]

Great information, thank you. I will continue to follow this thread and hopefully continue to learn something new. I wonder if bears have an Adam gene that would show they can all be traced back to one specific species which is currently known. If this is the case, it is possible that many strains might reverse and disappear. I am not sure if this would actually create a new strain...but then again...I guess it would depend on how you would define "Strain".

 

[DCasper]

The Wikipedia article was last updated on 16 Feb 12. It doesn't get much more recent than that...

 

[chickened]

Creation scientist can bring good theories to the table also. The same methods used for secular science to prove something can be applied to creation science to prove something after all a hypothesis is a belief. And what some areas of science concludes as a guess is no better. I think we should welcome creation science here if it stays civil.

Excellent insights, AE.
The Jews are descended from Semitic peoples, and their texts and scriptures are a conglomerate of the related ancient Semitic polytheistic religions of their ancestries, which is why there are so many contradictions in the first chapter of their Tanakh (scripture): "B'reisheet" ("In the Beginning," i.e. "Genesis").

That said, I hope we can continue to discuss the original topic and its related spin-offs without getting creationism tangled up with it!

 

[AquaEyes]

Remember that "species" is a man made term and does not necessarily mean that bears are separate as a species.

It's true -- we seek to impose black-and-white categories onto something that is not static. The definition of a species is more defined than many examples in nature. Nowadays, speciation is often measured in terms of genetic differences between populations, but that doesn't mean hybrids will never happen, or that the hybrids will always be sterile. The classification system we use today was actually composed at a time when species were believed to be fixed, perfect and unchanging. Nature isn't black and white, but fuzzy shades of gray, and doesn't sit still for long.

 

[GardenerGal]

I agree, chickened, that it's not a bad thing if discussions can remain civil. My thought was that it would be best to avoid arguments, which is usually what happens when creationism and science meet up. The main problem is that we are not on the same page in what a "theory" actually is.

The definition of" Theory" is not the same between "Science" and "Creationism." In my experience, the latter tends to interpret "theory" as being along the lines of "guessing." This is way off the mark, and because of this I don't believe that creationists can "bring good theories to the table" because "theory" in their definition is not what theory actually is. Science is a rational method, and cannot function on faith or belief; it requires hard, cold, unbiased testing and exploration of all possible hypotheses and continued testing of observable results.

AquaEyes has already pointed out the scientific (non-biased, non-subjective, not based on faith and hope) definition of "law" and "theory" (see link below), but here's a decent set of definitions for Hypothesis, Theory and Law: http://chemistry.about.com/od/chemistry101/a/lawtheory.htm

If we are all on the same page for this, then we might have some productive discussions that include both evolutionary scientists and creationists. If not, we'd just be talking past each other, and that's where the unpleasant arguments erupt.

Creation scientist can bring good theories to the table also. The same methods used for secular science to prove something can be applied to creation science to prove something after all a hypothesis is a belief. And what some areas of science concludes as a guess is no better. I think we should welcome creation science here if it stays civil.

 

[chickened]

That is correct and I would add that variations in DNA within a species is becoming more the norm than before. Scientist have used their new found ways to dissect things at the molecular level and beyond and I think as with species differentiation it has hurt them somewhat in the area of species identification. I would not be surprised if a little variation at the DNA level was someday shown to be normal within the species group in general.

I listened to a man today talk about how global warming model are way off in determining the warming predictions of the earth. They have learned that the sun has a more profound effect on the climate than before as the sun cycles and is not a constant source and is enough to throw off all the modeling. Apparently they have satellites now capable of measuring more accurately how heat escape the atmosphere and that too is happening at a much faster rate than the modeling inferred.

It's true -- we seek to impose black-and-white categories onto something that is not static. The definition of a species is more defined than many examples in nature. Nowadays, speciation is often measured in terms of genetic differences between populations, but that doesn't mean hybrids will never happen, or that the hybrids will always be sterile. The classification system we use today was actually composed at a time when species were believed to be fixed, perfect and unchanging. Nature isn't black and white, but fuzzy shades of gray, and doesn't sit still for long.

 

[perchie.girl]

Knew it .... not scientifically but just a gut feel. Loving the conversation....

deb

........

I listened to a man today talk about how global warming model are way off in determining the warming predictions of the earth. They have learned that the sun has a more profound effect on the climate than before as the sun cycles and is not a constant source and is enough to throw off all the modeling. Apparently they have satellites now capable of measuring more accurately how heat escape the atmosphere and that too is happening at a much faster rate than the modeling inferred.