Hi folks! Great to see some people already getting
psyched about isotopes! The reading for
this week is:
Ehleringer JR, Bowen GJ, Chesson LA, West AG, Podlesak
DW, and Cerling_ TE. 2008. Hydrogen and oxygen isotope ratios in human hair are
related to geography. Proceedings of the National Academy of Sciences
105(8):2788–2793.
For this week’s discussion, here are some questions
you may want to think about:
1) How
did the author’s parameterize their model? Given the ‘effects’ we talked about
in class, are their model results what we would expect?
2) Do
you think the model was effective? Why?
3) How
can we apply this model to other fields, such as forensics?
Happy reading!
I would to sign up for the stable iostope small group project.
ReplyDeleteMike J
This comment has been removed by the author.
DeleteI found this article very exciting because of the implications for anthropology and for forensics. The ability to pinpoint specific locations from hair samples would increase the ability to track local variations in isotopes found in tap water. The movements of people and the general movements of the population could easily be obtained this way.
ReplyDeleteForensic cases of unknown origin may have a better chance of being returned to their loved ones if anthropologists and other forensic investigators could pinpoint where a deceased individual was from and where that individual had been just prior to death. The article points out that usually individuals drink water and consume foods which are local, if this is not the case, recently consumed items may leave a particular trace which could also be found isotopically. This is an extremely exciting method and it would be awesome to do an analysis like this some time.
I'm taking a forensic anthropology class now and made that connection as well! In that class we were just reading about how there is more 14C in the atmosphere in general (and therefore bones) since nuclear testing started happening, which is just to say... analyzing isotopes can lead to all sorts of interesting information!
DeleteI also found these articles really exciting, (I can't get over how cool it is that it may be possible to figure out what kind of plants animals ate through their hair/ analyze human hair to figure out the person's origin)
I made a connection similar to this, Last time I was doing research there was still considerable debate about migration to the america's and the path it might have taken. If you could find early grave sites you might be able to use the change in isotope levels to track the route early humans took as they spread into the america's.
DeleteRight? It opens all kinds of possibilities, oxygen isotopes in rain water is also an interesting way to track local variations as well. Sherry Nelson has some really good classes about paleoecology that you might like, they're usually on Monday afternoons, but she teaches one pretty much every semester. They cover isotopic analysis and how they relate to local climate. I took her lab class and we actually got to go through all the steps to do an analysis. It was really cool.
ReplyDelete-J.Patterson
It would be interesting to somehow "know" the "assumptions" of 1) "continental supermarket dietary inputs" and 2) "it is likely that the majority of water input to humans reflects a local source".
ReplyDeleteFurthermore, "soft drinks, beer, coffees, teas, and reconstituted juices are likely to be derived from local waters" seems like a far reach.
For some reason it seems hard for me to imagine soft drink, beer, gatorade, red bull, monster, etc. to be using a local water source to get their products distributed all over the country. And it seems more people get their water through those types of drinks than from local tap water. In some cases local tap water dosnt even seem possible. Dosnt Southern California get most of if not all their drinking water from Northern California of the Colorado River? Isnt most of the "meat-byproducts" served in fast food "restaurants" actually shipped in from foreign countries?
These questions and many others make me wonder how accurate and precise the model created are.
Mike J
I would definitely agree with you in saying I’m not sure how accurate and precise this model would be nowadays. I mean we live in a more global society now so what we eat and drink isn’t so localized. I mean I think this model would probably apply to humans when things were grown locally. Therefore, I think this model would apply to helping our understanding of the past but it would most likely not work in the present.
DeleteI really enjoyed the article, but I have to side with Matt on the questions of the “assumptions” used. There are way too many things that can be misleading by this article. They say that they don’t even truly know that the hair they collect is from a local to the town.
ReplyDeleteHowever I do believe that with this starting point that the scientists have done has opened a very wide door. Knowing know that the correlation might be their, they can actually set up control groups for different states. This meaning that they find volunteers that are willing to limit the use of outsider water consumption and collect their hair throughout the year. I know that may seem highly farfetched, but it is one of the only ways to further support the correlation between the hair and water samples.
If this process is going to be used for forensic data it needs to be more complete or it may be just as hard to solidify as finger printing.
I would have to agree with Zach and Matt that the "assumptions" in this paper are far reached and that it really needs further research to determine the effectiveness in different kinds of populations. It could be better used in archaeological remains to determine mummies' locations and habits of life. It could also be used in a modern context if animals (without soft-drink inputs)were studied. For example, it might work well for determining range on animals like orangutans or equines.
Delete-J.Patterson
This article did have alot of assumptions and parameters that were unconstrained making it a little less solid for me. The assumption about local citizens using local water in everyday consumption may only be justified in saying they drink only fountain drinks that would use local water, tea that was brewed in tap water and they drink locally brewed beer and whatnot but that is highly unlikely, like the rest of us they probably consume a high amount of imported goods whether it be food or beverage. The random sampling they did also makes this article a little weak for me. However, archaeologists have used isotope data to look at the diet of ancient peoples as well as place these ancient peoples geographically and have been successful in doing so. I believe this approach, comparing tap water and hair, can be a very useful tool in forensics in identifying the place of origin of an individual, but seems that pinpointing the area of residence could be difficult if the person moves around often; I am under the assumption that the isotope signature in hair would only clearly match the signature in tap water if an individual has been consuming that water for a long period of time.
ReplyDeleteThis study was interesting because it sparked an interest in what the study of isotopes would do for the previous articles we've read. For example, the paleomagnetism article that we read could have been further studied by not only comparing the fossils of brachiopods but also in comparing the isotopes of the surround earth that the fossils were taken. It would help to get a better understanding on were our continents used to be and how they've changed over time.
ReplyDeleteThe study of isotopes for weather may also help the article we discussed about the "Snowball earth". Maybe finding isotope samples from around the globe would help to back up the findings found previously.
-Jacqueline Lee
Just read today some basic info on ice core, Antarctic tides, permafronst, and glacial modeling taught at Victoria University of Wellington Antarctic Research Centre. http://www.victoria.ac.nz/antarctic/research/glacial-modelling/default.aspx. Also yahoo just reported today the Russian's have just brought up core samples out of Antartica's largest freshwater lake. Biologists and glacierists are probably partying tonight!
DeleteMostly just agreeing with what's already been said.. Yeah, I think they did a great job of showing how isotopes in water affect the isotope composition of hair, but not necessarily because their methods were without failing (though fig. 1 shows a pretty strong correlation, how else could that have come about?)
ReplyDeleteI thought collecting random hair from barbershops was really odd, and probably budget/time related, as I think the best thing would have been to have subjects that could be asked about their consumption habits.
I got really excited about the person from China whose hair was analyzed chronologically to show the change in isotopes when they arrived in the US (though the graph didn't mark the point when the person arrived) and I wish they had repeated that test more than once.
Under “Discussion” The article reported an assumption the majority of water input to humans reflects a local source. Soft drinks, beer were used as an example. Milk was assumed to be likely derived from animals growing in the region. However, what research I have read or documentaries I have seen about food production in the U.S. does not support the assumption of local water being used to product soft drinks, beer and milk. Nonetheless, the implication of spatial isotope ratio variations in human hair was with respect to specifying regions of origin in anthropological, archeological and forensic studies is of great interest. What was surprising was that karatin in the study sample of the man from Beijing, China changed so rapidly, considering that the substance was karatin, not a soft tissue. Another point of interest was the isotopes being found in rain, could this be used as an indicator of wind blowing isotopes from other areas? But then I got distracted by a sudden and vain attempt trying to visualize isotope interactions with other chemicals resulting in acid rain….
ReplyDeleteAs many have stated, the assumptions of the model needs close scrutiny. Obviously, the implications of this study are very cool, but a close examination of the assumptions may lend less credibility to the conclusions. With respect to the issue of local vs imported food and water, I presume that's only a problem in the past few decades - much longer than that, and human hair (or other tissues) would have reflected the local environment much more accurately as we can (I think safely) assume much less transport of goods. It would be interesting to link things like spice trade routes, textiles, etc to populations in the past few millenia. What possibilities!
ReplyDeleteI can see both sides of these different views. I think it is a good start. Even though we import most goods, we have to remember that a lot of companies are so "big box" and connected that most likely a large amount is ordered from the same area. I cannot really explain what I am trying to say. I guess the main point is that a geological area can at least be studied and as far as forensics go, maybe if a body was found up north, but the hair matched say a Florida Texas profile, that could be a starting point to check unsolved cases. I believe it was a great start. I enjoyed the info they found on the hair from China to the US and I think it would be interesting and exciting to see a more thorough study with details like this to compare.
ReplyDeleteI liked this paper because of the applications on forensic anthropology and of just of the general idea. I agree that it is a large assumption that people drink local drinks. This makes me think of the overwhelmingly popular bottled water industry. A thought occurred to me that the only way that soda would have local water is if it came from a soda fountain and was mixed with the producers syrup. As for beer, the most poplar beers only have a few plants that are used for regional distribution. I still think that it is a really awesome idea but that it needs to be changed some.
ReplyDeleteI was trying to connect this with climate change through time and was having a hard time. Since the oldest fossilized human hair is (maybe) 200,000 years old or so (no too old geologically), wouldn't oxygen and hydrogen in bone be more relevant? or is there a reason that is harder to study?
ReplyDeletePutting time scale aside, by analyzing hair you could figure out the isotope ratios of O and H in the water of that area... would that be enough to predict precipitation patterns? (for example very isotope enriched water would mean a lot of evaporation was happening there)... is there an advantage to this analysis as opposed to figuring out what type of plants animals in the region ate from analysis of the isotope ratio in their teeth and inferring climate from that?
poking through some abstracts to get an idea...here's a paper that says isotope ratio Oxygen in fossil bone is subject to change over time... (1993)
ReplyDeletehttp://www.gly.fsu.edu/~ywang/pdf/Paper9.pdf
but then here's a more recent one that hopes to get around that (2003)
http://www.colorado.edu/anthropology/faculty/sponheimer/pdfs/LeeThorpandSponheimer03.pdf
oo, and here's a pretty cool recent one still trying to get around that, (though they say its only applicable in very small animals right now)
http://apps.webofknowledge.com.libproxy.unm.edu/full_record.do?product=UA&search_mode=GeneralSearch&qid=5&SID=2Fghbfh85BKC141dDh5&page=1&doc=9