(HRI) Human or Non-Human Remains? Lesson

Human or Non-Human Remains? 

When discovering remains, an investigator must first decide if the remains are human or non-human in origin. In order to do this, they must first determine if the article they are examining is bone. It could be pottery, wood, plastic or stone that only appears to be bone. This determination is more difficult if the pieces are damaged, burned or warped because they become less characteristic of their usual appearance. If the investigator decides that it is in fact bone, they must then determine if it is human bone. All humans are animals, so investigators must differentiate and identify if the bone is human in origin; often this more difficult than imagined because many non-human mammalian bones look similar to human bones.  Forensic Scientists examine bones on three levels when making a determination of bone origin:

1. Gross Skeletal Anatomy
2. Bone Macrostructure
3. Bone Microstructure

Gross skeletal anatomy refers to the characteristics of bones that can be observed by the unaided eye such as the number or orientation of the bones. An investigator is looking at three areas of the gross skeletal anatomy classified as: the cranium, dentition, and post-cranial bones.

Gross Skeletal Anatomy

	Humans	Non-Humans
Cranium (Head)	-Large skull area for brain -Have chin -Orbits (eye sockets) are at the front and above the nose area. -U-shaped Mandible -Relatively small face	-Small skull area for brain -Chin is absent -Orbits are at sides of face and behind or posterior to nose area. -V-shaped Mandible
Dentition (Teeth)	-Omnivorous -Dental Formula of 2:1:2:3 (meaning 2 incisors, 1 canine, 2 pre-molars and 3 molars) -Large incisors -Small canines Molars are low and rounded with grooves	-Can be carnivorous, herbivorous or omnivorous. -Other Dental Formulas such as 3:1:4:3 (bear), 3:0:3:0 (horse) or 5:1:3:4 (Opossum). Teeth vary by diet; for example, carnivores have large canines, herbivores have small or no canines.
Post-Cranium (Rest of the Body)	-Upper limbs are smaller and less muscular. -Separate radius and ulna arm bones. -Vertebrae are broad and flat with short spiny processes. -Pelvis is broad, short and bowl-shaped. -Separate tibia and fibula leg bones. -Long, narrow foot that bears weight on heels and toes.	-Larger or proportional upper limbs. -Radius and ulna are often fused into one bone. -Small vertebrae that are either concave or convex with long spiny processes. -Long, narrow blade shaped pelvis. -Often the tibia and fibula leg bones are fused. -Broad foot that bears most of the weight on the toes.

Interactivity: Bone Identification

The difference between human and non-human bones is mostly due to the way in which humans and other animals walk or move.  Humans walk bipedally, or on two legs, so their upper limbs are not proportional to their lower limbs because they are not used in the same way.  While some bones are noticeably different between species, others look very similar to each other.  The most commonly mistaken bones are the bones of infants.  Infant bones are much smaller and are often shaped differently than adult bones because they are still growing and developing.  Many infant bones look very similar to other animal bones.  The bones in a raccoon paw, for example, are sometimes mistaken for human infant hand bones.  The bones of a bear paw are also often mistaken for a human's hand bones because of their similarities.

Bone Macrostructure

Bone macrostructure refers to the structure of the individual bone that may be seen without magnification such as the shape, thickness or color of the bone.  While determinations can't always be made using bone macrostructure characteristics, there are a few clues that are more telling of a human bone:

Bone Macrostructure

Human Bone Macrostructure	Non-Human Bone Macrostructure
More porous 1/4 the thickness of the diameter of long bone.	-Less porous 1/2 the thickness of the diameter of the long bone.

Bone Microstructure

Bone microstructure is the microscopic structure and characteristics of the bone.  Forensic Science is interested in a microscopic structure in the bone known as Osteons or Haversian Systems. Osteons are units of bone that include bone cells, known as Osteocytes, surrounding Haversian Canals.  Haversian Canals are openings in the center of compact bone that surround blood vessels and nerves within the bone.

When comparing Osteons of human bone to Osteons of non-human bone, the difference is not always clear. Often it is a difficult distinction to make that is based on the subjective opinion of an expert in that area. Though it is far from certain, it is still a method that is often used when trying to determine whether a bone or bone fragment is human in origin.  Some research indicates that the age and sex of the victim may be determined by examining the osteons in a bone as well.

Osteons of Human Bone Comparison

Human Osteons	Non-Human Osteons
Osteons are scattered and evenly spaced.	Osteons are aligned in rows or in rectangular patterns.

Though microscopic features of bone can potentially confirm whether bone is human or non-human in origin,  it is impractical in the field at the scene.  Also, because so much variation is found among animals, sometimes it is impossible to distinguish human and non-human bones by just looking at the osteons. Forensic Scientists must rely on the expertise of osteologists, or scientists who study bones and skeletons.

Other Considerations of Skeletal Remains

Other considerations of skeletal remains that must be made include how many bodies are represented in the remains that are found and determining how long ago those remains were buried. Some investigative guidelines used in examining skeletal remains for these considerations:

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