Thermoregulation Controlling Temperature. WHAT IS THERMOREGULATION?
Untangling a Hair-y Science - McCroneUntangling a Hair-y Science Sandra Koch, PhD What’s so...
Transcript of Untangling a Hair-y Science - McCroneUntangling a Hair-y Science Sandra Koch, PhD What’s so...
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Untangling a Hair-y Science
Sandra Koch, PhD
www.hookecollege.com
What’s so special about hair?
Hair is one of the defining features of mammals
– Protection
– Thermoregulation
– Tactile sense
– Cultural identity
– Signaling
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What’s so special about hair?
Hair is one of the defining features of mammals
– Protection
– Thermoregulation
– Tactile sense
– Cultural identity
– Signaling
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Who studies hair?
• Forensic Scientists
• Anthropologists
• Geneticists
• Biologists
• Cosmetic Industry
• Mammologists
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Sample Preparation
Light microscopy
• Mounting medium needed
– Air or water alone doesn’t work so well
Scale casts
• Nail polish : acetone
• Glue : water
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Microscopical Hair Analysis
• Is it a hair?
• Human or non-human?
• Can body area be determined?
• Are there features useful for estimating ancestry or species?
• Any characteristics of disease, damage, chemical alteration, or decomposition?
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Non-human Mammalian Hair3 Types:Whiskers – sensoryGuard Hairs – protection and camouflage (can be morphologically differentiated among animal families)Underfur – insulation
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Human Hairhead, pubic, facial, axillary, chest, limb, and eye
Head and pubic hair are suitable for microscopical
comparison
Head
Eyelash
LimbPubic
Facial
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How Hair Grows
• Timing (seasonal vs asynchronous)
• Growth cycle and rate
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Morphology
Human Hairs Non-human Hairs
This
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Microstructure
Deedrick, Douglas W., and Sandra L. Koch. "Microscopy of hair part II: a practical guide and manual for animal hairs." Forensic Science Communications 6.3 (2004).
Dog Hair
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Microstructure
• Medulla
• Pigment distribution
• Color
• Cuticle
furCat fur
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Hair Pigmentation
• Humans:
– pigment granules distributed toward cuticle
– no banding
• Non-human mammals:
– pigment granules distributed toward medulla
– can be banded
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Electron Microscopy
SEM TEM
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Transmission Electron Microscopy
• Ultrastructure
– Cuticle layers, melanosomes, cortical cells, etc.
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Damage or Alteration
• Dyed or bleached
• Decomposition
• Insect bites
• Fungal tunneling
Tridico, Silvana R., et al. "Interpreting biological degradative processes acting
on mammalian hair in the living and the dead: which ones are
taphonomic?." Proceedings of the Royal Society of London B: Biological Sciences 281.1796 (2014): 20141755.
Image credits:
Deedrick, Douglas W., and Sandra L. Koch. "Microscopy of hair part 1: a
practical guide and manual for human hairs." Forensic Science Communications 6.1 (2004).
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Ancestry
• Cross-sectional shape
• Diameter
• Cuticle thickness
• Pigment patterns
• Degree of curl
How reliable are these traits?
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Old Terminology:
Scientifically Invalid
Racial
classifications
Caucasoid
Negroid
Mongoloid
Typological model fails
because most biological traits are continuous variables.
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Resource Guidelines
• SWGMAT guidelines
http://www.asteetrace.org/WebPages.cfm?action=viewCat&BIZ_UNL_id=41614
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Training
• Hooke College of Applied Sciences Hair Course
• Benefits:
– Practical exercises
– Interaction with scientists from different laboratories
– Extensive training samples associated with known ancestry and from a variety of identified species
– Ability to start building your reference collection
– Discussions on report writing and significance
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Questions?
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https://www.zmescience.com/oth
er/feature-post/why-we-get-
goosebumps/
https://ru.m.wikipedia.org/wiki/
%D0%A4%D0%B0%D0%B9%
D0%BB:Whiskers.jpg
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g/wiki/File:Arctic_Foxes_(8154
290495).jpg
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ca-Wild-Animal-Cat-Predator-
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-us/lab/forensic-science-
communications/fsc/jan2
004/research/2004_01_r
esearch01b.htmhttps://commons.wikimedia.org/wiki/File:Red_hair_close_up_wavy.jpg
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gouti_(coloration)
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use.com/blog/2012/02/
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http://www.personal.psu.edu/users/c/l/clv14/
sci101/hair.htm
Image Attributions