The study of the decomposition of hair over time

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Postby Louise » Tue Oct 16, 2007 6:25 am

Rosemary wrote:on a side note. i was wondering if i could somehow get Geoff Bruton's email. I cant find it online. thanks


We aren't allowed to give you or emails or contact you directly. This is part of the terms of this site; all contact is through the forums for safety.

I'm concerned about your project as stated (monitoring the hair from an dead animal). You really need to clear this with your teacher and and talk to your parents about this.


Louise
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Postby wildfirefox » Tue Oct 16, 2007 7:34 am

Rosemary wrote:on a side note. i was wondering if i could somehow get Geoff Bruton's email. I cant find it online. thanks


Sorry Rosemary. There's no person contact one-on-one for project discussion. Forum's policy. It's a lot better for you to interact within the forum, since the experts can all share their info with you.
Those who can see that do not exist are geniuses. Those who can see what exists are brilliant. Those cannot see what exists are ignorant.
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Postby geoffbruton » Tue Oct 16, 2007 8:04 am

Rosemary wrote:For my experiment, i am planning on using a dead animal to study the stages of hair decomposition after death while still in the scalp. When the animal dies, i would like to pull a hair and look at the root. I could pull a new hair every couple of hours to see how the hair root has morphed. I need a way to measure or record the hair root. I could use appearance, but that seems kind of subjective. Mass may also work, but it would be very light weight. Do you have any ideas on how to measure the hair root at its different stages?


Hi Rosemary,

Okay, now I see why you were specifically wanting to look at hair (or fur) in relation to its source. This sounds very interesting, but I would echo the comments already posted by my learned colleagues in that I would question if the use of a deceased animal is a) absolutely necessary for your project, and b) if your teacher and the science fair board are okay with this subject. Please check with them before you take this any further. I honestly believe that there are suitable alternatives to carrying out this project which can then be applied to the specific question you are trying to answer. (By the way, what is your hypothesis?)

What has your background research uncovered as to what happens during decomposition, and specifically with regards to soft tissue and hair? What do you *expect* to happen to the root of the hair over time (that is, what do you predict will happen / that you will observe)? And would you expect these observations to be the same in decomposing tissue and hair versus plucked hair?

In an earlier post, I had asked you to look into the different growth stages of hair. What did you find and how can you apply this knowledge to the question at hand? If, for example, a head hair is plucked from the scalp, you may expect to see an intact root with cellular material attached to it. How does this differ (visually / microscopically / physically) from a head hair that naturally falls out? Why? What process has the hair / root undergone in order for this natural process to occur?

You had also previously mentioned that a researcher had done some work in virtually the same area that you were wanting to do your project. What was the initial purpose of the research and what were the observations and conclusions from the paper? If you can let us know more about the work that has already been done, we might be able to help you refine the experimental phase of your project.

You had also asked about how to measure the observations you make. Again, how did the researcher cover this in his/her work? I would suppose that as long as you make multiple examinations within each given time frame (to allow for variability), visual observations of what is occurring would be satisfactory. On the other hand, would you expect the hair and cellular material to dehydrate over time, depending upon the environmental conditions in which the decomposition occurred? If so, you may wish to consider the change in weight over time - but this may be extremely difficult to measure, depending upon what resources you have available.

Rosemary wrote:on a side note. i was wondering if i could somehow get Geoff Bruton's email. I cant find it online. thanks


As others have already pointed out, I'm afraid that is against the rules of this forum. I would be more than happy to continue our discussion using this same thread - and that way, any others in the future who may wish to continue your research will have a head start! (Sorry for the awful pun!)

I will also discuss your project with some colleagues of mine who work in the Trace Evidence Section here at the lab. They work with hair - including hair from living and dead humans and animals - on a relatively frequent basis. If they have anything to add, I will certainly post it here.

Good luck with everything, and please let us know your thoughts.
Geoff.
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Postby Rosemary » Tue Oct 16, 2007 4:26 pm

For my project, i need to use a dead animal to see if i can determine a correlation between the dead hair root and the time of death. If i can perfect my procedure with animals, then someday i hope to use my information on humans.
In the research paper i found, the researcher found a direct correlation between dead human roots and time of death. However, her procedure is a little different than mine and she made her observations visually, which seems kind of subjective. Instead of plucking the hair and looking at it immediatly, she pluckd them all at once, then studied their decomposition over a period of time.
So basically for my project, id like to see how the study of root morphology can determine post mortem interval.
Kelly
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Postby Alison » Wed Oct 17, 2007 10:08 am

Hi Rosemary,
One of the other experts on this forum happens to be one of my coworkers, Heather Mostman. She's working on a project right now where she's measuring different characteristics of hair on marine mammal pelts! I gave her a call because I think she's a perfect person to help you decide which root characteristics to measure with equipment you currently have available or how to find other equipment if you decide you need it. She should post here later today.

Good luck!
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Postby Louise » Wed Oct 17, 2007 10:53 am

Rosemary wrote:{snip}
In the research paper i found, the researcher found a direct correlation between dead human roots and time of death. However, her procedure is a little different than mine and she made her observations visually, which seems kind of subjective.
{snip}


What are you planning to do, if you aren't going to measure them visually? As long as you have very clear criteria, I don't think visual examination is necessilary subjective.

I'll say this one more time, and not mention it again. Where are you getting a dead animal? Where are you planning on storing a rotting animal? [And scientific questions are associated with this too- how controlled will this environment be?] How are you going to make sure this does not become a source of disease? Is this legal in your city or town? Does your school require specific permission for dealing with animals? Have your parents approved of this experiment, and do they understand what is involved?

I think you have an interesting research question, but I think you have not thought carefully about the reality of the project. Several people have asked you questions about this, and you haven't answered any of them. Better to address these questions now, rather than half way through the experiment.

Louise
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Postby heatherL » Wed Oct 17, 2007 11:12 am

Rosemary wrote:For my project, i need to use a dead animal to see if i can determine a correlation between the dead hair root and the time of death. If i can perfect my procedure with animals, then someday i hope to use my information on humans.


Hi Kelly,

I am the colleague that Alison mentioned. I read your thread with great interest! As part of my Ph.D. thesis, I have been examining hair characteristics of carnivores. One thing that I can tell you is that you would not necessarily need a whole dead animal to do this project. For my project, I obtained pelts (skin with the fur attached) from different animals. My pelt samples are just squares cut from a consistent location (e.g., the back, just below the shoulders). One way to get samples like this is to ask places like the Humane Society, which (unfortunately) have to put some animals to sleep or may perform necropsies (animal autopsies) on wild animals that have died. You may need to call around to your local organizations. Some veterinary clinics may be able to put you in touch with the right people.

There is a SAFETY CAUTION with this. If the animals died of natural causes, there may be pathogens (disease-causing organisms) still present. Make sure you always wear gloves when handling pelts.

Rosemary wrote:In the research paper i found, the researcher found a direct correlation between dead human roots and time of death. However, her procedure is a little different than mine and she made her observations visually, which seems kind of subjective. Instead of plucking the hair and looking at it immediatly, she pluckd them all at once, then studied their decomposition over a period of time.
So basically for my project, id like to see how the study of root morphology can determine post mortem interval.


When it comes to your procedure, take a look at what characteristics the researcher monitored. One characteristic that you can quantify (meaning, get numbers for) is the diameter of the hair root. This is not so subjective. A research assistant and I have been examining the length and diameter of hairs. The procedure is relatively simple. We use clear nail polish to ensure that the hair lies straight on a plastic sheet. Then we use calipers to measure the hair length. You could do the same for the root length. From there, we carefully cut a cross-section of the hair. Then we look at the cross-section under a compound light microscope, to which you should have access at school. Our microscope has an ocular micrometer, which is a tiny scale that you can see through the viewing lens. This scale allows us to measure and compare the diameter of the hairs.

Note that the hairs are not always perfectly round. They are often shaped like an ellipse. Because of that, we measure both the largest diameter and the smallest diameter of each hair.

You should be able to measure lengths and diameters of hair roots, using a similar procedure. Decomposition and dehydration would likely change these parameters, and then you would have objective numbers to report.

Good luck, and please write again if you need more help!

Cheers,
Heather
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Postby Rosemary » Fri Oct 19, 2007 7:49 pm

Both my parents and teacher say this project is okay to do. Actually, they are both more than willing to help me on it. I need to come up with a hypothesis. I figure that over time, the hair root will shrink in diameter and length, based on other research. I also think that I will find a direct correlation between the size of the root and the time of death. I am just not sure on how to phrase my hypothesis. Can you help me form one?

Also, thanks for all the help everyone. I really appreciate it.
Kelly
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Postby heatherL » Fri Oct 19, 2007 8:44 pm

Both my parents and teacher say this project is okay to do. Actually, they are both more than willing to help me on it. I need to come up with a hypothesis. I figure that over time, the hair root will shrink in diameter and length, based on other research. I also think that I will find a direct correlation between the size of the root and the time of death. I am just not sure on how to phrase my hypothesis. Can you help me form one?


You are already there! A hypothesis is a prediction of what you expect to happen, based on your knowledge of previous research. From what you said, you have two predictions:
1) The hair root will shrink in diameter over time.
2) The hair root will decrease in length over time.
From these predictions, my understanding is that you hope to be able to estimate the time since the animal died, based on the changes in the hair root.

If your hypotheses are correct, your results will show a correlation between the size of the root (diameter and/or length) and the time of death. (What kind of correlation do you expect - positive or negative?)

Now it's time for you to think about how you can estimate time of death. How can you use your correlation? If you have a hair that has already undergone some decay, how do you predict the time that has passed? To what do you need to compare your hair?

Good luck, and feel free to post again with further questions!

Cheers,
Heather
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Postby Rosemary » Sun Oct 28, 2007 7:23 pm

when I pull the hairs, what time interval should I use? Should I pull them every hour, once a day, or once a week? Will I get results after a few days, or does it take longer for the root to change shape?
Kelly
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Postby heatherL » Sun Oct 28, 2007 11:33 pm

when I pull the hairs, what time interval should I use? Should I pull them every hour, once a day, or once a week? Will I get results after a few days, or does it take longer for the root to change shape?


Hi Kelly,

My inclination is to say once a day, but it is not really based on knowledge. Do take a look at the research paper you found, and see how quickly the author reports seeing changes in the hair roots. That said, if you are unsure of the time frame in which the hair roots will change, you'll want to check the hairs at the same resolution at which you hope to predict time of death. If you want to predict time of death by how many days have passed, then you should pull hairs at least every day. If you want to predict time of death with greater resolution than that, you should pull hairs more often. I think that once a week is too long.

Keep up the good work! :)

Cheers,
Heather
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Postby Rosemary » Wed Oct 31, 2007 9:06 pm

I need to get a dead rat for my project. I know that they are killed often in labs for research which should make it easier to get. Do you know where I can get one? thanks
Kelly
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Postby heatherL » Thu Nov 01, 2007 9:46 am

I need to get a dead rat for my project. I know that they are killed often in labs for research which should make it easier to get. Do you know where I can get one? thanks


Hi Kelly,

I'm not sure exactly where you're located, but local universities would be a good place to start. Universities often have research labs that have to euthanize rats from research projects. I will check at my university and get back to you with more specific information.

Cheers,
Heather
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Postby Rosemary » Sat Nov 17, 2007 8:51 pm

For my experiment, are there any independent variables? Im not sure. I know that they are the things that you change in your experiment, so would it be the times at which I pull out the hairs? So therefore, the dependent variable would be the shape and size of the root?
Kelly
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Postby MelissaB » Sat Nov 17, 2007 10:16 pm

Rosemary,

That's exactly right. 'Time since death' would be your independent variable, and the size and shape of the root would be your two dependent variables. If you need more information, there's a section on variables in our science fair guide (link is in upper left-hand corner of this page).
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