HUMAN REMAINS
The Four Mortis
Imagine a pathologist named Larry. Larry is very good at what he does. The police found a body and brought it to Larry today.
"Ay ay ay," says Larry.
The body had a lot of issues: it was found more than 24 hours after death, so Larry could not use the Algor Mortis formula, or Glaister formula, to find out what time it had died accurately based on the temperature of the body.
"Ay ay ay," says Larry.
The body had a lot of issues: it was found more than 24 hours after death, so Larry could not use the Algor Mortis formula, or Glaister formula, to find out what time it had died accurately based on the temperature of the body.
Larry could not make any estimations, as the body had cooled off completely.
Larry tried to look for signs of Livor Mortis, which is the pooling of blood after the heart stops, caused by gravity; this will cause purplish-reddish marks at the lowest parts of the body. He was able to find marks on one side of the body and face, which was weird as the police had found this body sitting under a tree. The top of the face also showed Pallor Mortis, a discoloration caused by the body moving to the opposite side due to gravity.
"Someone moved this guy!"
Larry tried to look for signs of Livor Mortis, which is the pooling of blood after the heart stops, caused by gravity; this will cause purplish-reddish marks at the lowest parts of the body. He was able to find marks on one side of the body and face, which was weird as the police had found this body sitting under a tree. The top of the face also showed Pallor Mortis, a discoloration caused by the body moving to the opposite side due to gravity.
"Someone moved this guy!"
But Larry lucked out. The body was almost out of Rigor Mortis, which usually starts happening right after death. The muscles relax and ATP (adenosine triphosphate) starts breaking down, changing fluid concentrations and causing the body to become rigid. This process starts in the smallest muscles of the face, jaw and neck, and then progresses to the rest of the body. At about 30 hours, the muscles of the face start relaxing again, followed by larger muscles of the arms, legs and body. Larry noticed that the face and jaw of the deceased were soft, but not his arms and legs, so he could say that the person had died a little over 30 hours ago.
Forensic Anthropology
As it turns out, Larry is not only a pathologist, but also has a degree in forensic anthropology. He spent a long time studying the changes and variations of human skeletons, so he could tell the approximate height, weight, sex and even if a person was black, white or Asian (although sometimes Larry gets it wrong because there are many more people with mixed backgrounds).
Larry is very good at what he does. He can say all these things even if the body has decomposed or has been on a fire. All he needs is the skeleton. In fact, Larry can tell a lot from a simple bone fragment. Under a microscope, human bones have smaller and rounder osteons, which are holes where the blood supply can travel; meanwhile, animals have osteons that form a regular pattern and are longer.
Larry is very good at what he does. He can say all these things even if the body has decomposed or has been on a fire. All he needs is the skeleton. In fact, Larry can tell a lot from a simple bone fragment. Under a microscope, human bones have smaller and rounder osteons, which are holes where the blood supply can travel; meanwhile, animals have osteons that form a regular pattern and are longer.
A skeleton
We have 206 bones in our bodies. The bones protect our organs and provide places for muscles to attach. Tendons connect the two. The muscles, bones and tendons work together to move us and help us do many different things. To ensure things can more the proper way, we also have joints.
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Some illnesses stop joints from moving, such as osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis, which causes the whole body to be unable to move.
Ankylosing spondylitis is the worst -- it actually fuses the bones together, like the photo shown here. |
Many animals do not need skeletons, but they are also not as developed as animals that do. Skeletons and muscles help a body move faster and achieve more.
In some bones, there are ossification sites which can help determine the age of a skeleton. These sites show growth and activity until the late teens, so they can be used to identify the age of a skeleton that is young.
In some bones, there are ossification sites which can help determine the age of a skeleton. These sites show growth and activity until the late teens, so they can be used to identify the age of a skeleton that is young.
Let's complete the skeleton on our worksheet together!
Height of a skeleton
Larry can estimate the height of a person just based on the size of some of their bones, with a tiny margin of error of plus or minus 7.5 centimeters. Can you believe it? And now, you will also be able to do it, if you ever find a skeleton and are wondering just how tall the person was.
PSA - FIRST call the cops, THEN take out your calculator.
PSA - FIRST call the cops, THEN take out your calculator.
Estimated height of a biological female:
Height = Femur length X 2.21 + 61.41
Height = Tibia length X 2.53 + 72.57
Height = Humerus length X 3.14 + 64.97
Height = Radius length X 3.87 + 73.50
Height = Tibia length X 2.53 + 72.57
Height = Humerus length X 3.14 + 64.97
Height = Radius length X 3.87 + 73.50
Estimated height of a biological male:
Height = Femur length X 2.23 + 69.08
Height = Tibia length X 2.39 + 81.68
Height = Humerus length X 2.97 + 73.57
Height = Radius length X 3.65 + 80.40
Height = Tibia length X 2.39 + 81.68
Height = Humerus length X 2.97 + 73.57
Height = Radius length X 3.65 + 80.40
As you can see, there are four different bones you can use to figure out the height of a person. Which is good, because sometimes if the body was left outside, animals can get to it, and you may only have one bone left. You will still have to identify the bone, but thankfully it's not so hard to do, as every bone is very different and has specific shapes.
Let's see if we can figure out how tall these people were based on their bones:
1) A male skeleton has a humerus 34.9 cm long. How tall was he approximately?
2) A tibia was found, and it was 34.8 cm long. How tall was this person if they were a biological man? How about if they were a biological woman?
2) A tibia was found, and it was 34.8 cm long. How tall was this person if they were a biological man? How about if they were a biological woman?
Sex Determination
Determining sex is super important when figuring out the identity of a person. You cut off about half the population right there! The Os Pubis, Sacrum and Ilium of the pelvis are bones with the most obvious differences when looking at men and women. The shape of the skull, the mandible and the size of the occipital bump (behind the head) are also big indicators.
Men tend to have bigger bones than women, as well as larger areas for muscle attachment on the bones (looks like a rough area). The sacrum is straighter in females and more curved in males. There is also a ridge that appears on the female pubic bones, usually around the time a woman is in her 20s. This also helps identify the age of a skeleton!
Men tend to have bigger bones than women, as well as larger areas for muscle attachment on the bones (looks like a rough area). The sacrum is straighter in females and more curved in males. There is also a ridge that appears on the female pubic bones, usually around the time a woman is in her 20s. This also helps identify the age of a skeleton!
Determining Race
Determining the race, or genetic background, of a person has become increasingly difficult due to the fact that people with mixed backgrounds and provenance have become increasingly common in the past couple hundred years.
However, a few benchmarks are still valid, and can still help get at least close to what a person would look like. Most of these differences will be seen in the skull.
** Important -- there is more variation within the same race than there is variation between different races. Imagine aunt Trixie with her button nose and uncle Roger with his huge nose with the bump that could stop a truck -- and they are brother and sister! **
However, a few benchmarks are still valid, and can still help get at least close to what a person would look like. Most of these differences will be seen in the skull.
** Important -- there is more variation within the same race than there is variation between different races. Imagine aunt Trixie with her button nose and uncle Roger with his huge nose with the bump that could stop a truck -- and they are brother and sister! **
European descent
- Eyes: oval eye orbits with rounded corners, like aviator glasses
- Nose: Longer and narrower nose aperture, pinched at top, pronounced and narrower nose bridge
- Face: narrow zygomatic arches
- Mouth: Triangular palate, smaller teeth, close together, maxillas protrude more
- mandible: narrow mandibles
Asian Descent
- Eyes: Circular eye sockets
- Nose: Nasal aperture looks like upside-down heart, nasal bridge is pronounced but not too much and a little bit less narrow
- Face: wide zygomatic arches
- Mouth: parabolic palate
- Mandible: pointed mandibles
African Descent
- Eyes: Rectangular eye sockets with rounded corners
- Nose: Wider nasal aperture, shorter and wider nasal bridge
- Face: pronounced zygomatic arches
- Mouth: rectangular palate, larger teeth in general with a generally wider gap between them
- Mandible: stronger mandibles
Let's lake a look at one more photo, showing differences between biological female and biological male skulls.
