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Differences Between Human Bones & Artefacts

According to the medical dictionary, bone is a hard and rigid connective tissue existing in  most  vertebrates, including mammals, fish, amphibians, reptiles, birds, primates, rodents and marsupials (Figure 1). Bone is one of the strongest biological material in existence, particularly in terms of bearing weight and giving support to  the movement of the body.

It is  important for Forensic Anthropologists, Physical Anthropologists and Archaeologists to  identify human bones and differentiate them  from non-human bones, i.e. artefacts and animal bones. For layman, this matter may sound trivial  but for a scientist  dealing with  human bones,  this question is very pertinent from the forensic viewpoint before embarking on any further investigation or  research.

As shown in Figure 1 below, when the skeleton is in an intact condition, it is not difficult to  identify the species of the bone. Unfortunately, in most  cases, the bones are  incomplete, fragmented, and even commingled (consisting more than one individual human skeleton  or mixed with animal bones ) (Figure 2). Hence, identifying human bones is a critical step in every anthropological case.

There are various methods in differentiating  human bones from non-human bones. Generally, it can be divided into three methods – macroscopic,  microscopic and bio-chemical methods.

a) Human skeleton – adapted from http://animal-kid.com/fish-skeleton.html

b) Bird skeleton – adapted from http://www.dappercadaver.com/products/small-bird-skeleton-quail.html

c) Amphibian skeleton – adapted from http://scienceblogs.com/tetrapodzoology/2007/10/28/frogs-toads-sheer-untold-awesomeness/

d) Fish skeleton – adapted from http://animal-kid.com/fish-skeleton.html

e) Reptile skeleton – adapted from http://searchpp.com/reptile-skeleton/

f) Primate skeleton – adapted from http://www.turbosquid.com/3dmodels/chimpanzee-skeleton-3ds/654529

g) Rodent skeleton – adapted from https://www.flickr.com/photos/galleriejc/3979155157/

h) Marsupial skeleton – adapted from https://twitter.com/mvmammals/status/496534172471545856

Figure 1: Skeletons of different vertebrates.

 


a) Adapted from http://www.age-of-the-sage.org/evolution/ardi_fossilized_skeleton.html

b) Adapted from http://www.texasbeyondhistory.net/landis/pipeline.html

c) Adapted from http://pages.vassar.edu/realarchaeology/?tag=lab-work

Figure 2: When  bones are not catalogued systematically, this will cause difficulty in identifying human bones.

Macroscopic Method

  1. Gross Visualization

    In identifying human bones, it is recommended  that the examiner  has an intact comparative skeleton close at hand, even in remote fields. This is because human bones can be confused with many animal bones, especially primates, even though with  experienced anthropologist.

    Quoting  Dr. William Bass, a renowned anthropologist, it is  best to hold or touch the bone elements  ourselves, as there is no illustration or  description  that is as good as comparing with  actual bone. Secondly,  one should familiarize himself/herself with as many animal bones as possible, especially  animals that can  be found in the local area or habitat  where the skeletonised remains were found. This is  important when encountering human bone-like structures  as they can be very similar to animal bones or even artefacts like a dried twig or tree branch. There is noticeably subtle differences between human bones and animal bones as there are fine morphological variations in the bone features.

    Schwartz and Schwartz produced a book called “The wild mammals of Missouri” in year 1959, which illustrates  line drawings of animals as well as  bones of the animals.  This  book can act as guide  for the inexperienced anthropologist  in distinguishing between  human bones and  non-human skeletal  remains.

    With good  reference guide and from direct gross visualization, one can actually tell that it is human bones macroscopically  without  conducting further examination. For example, it is not difficult to  differentiate between femora of  a child with  the femora of an adult dog as there will be  no fused epiphyses in  the child’s femur (Figure 3).


    Figure 3: Femora of a 3-year-old child (180mm) (left) and an adult dog  (166mm). They are of similar size, but the epiphyses of the adult dog have united whereas there are no fused epiphyses on the child’s femur. (Adapted from Robert, J., PPT: Forensic Anthropology, 2014)

  2. Examination and Measurement

    Besides gross visualisation of the bone elements,  detailed examination of the size, shape, density and surface structure of bones using a hand held magnifying lense can also elicit morphological features of the bone. .

    According to Julie Robert, humans are bipeds whereas most animals particularly mammalians  are quadrupeds, so a human being will possess the following features:

    • Shorter  ‘dish shaped’ pelvis.
    • Present of foramen magnum at the base of cranium.
    • Adaptations of hands and feet.
    • 3 curves of the spine.

    Julie Robert also mentioned that  when comparing to humans, animals like horse, pig and cow have fused 3rd and 4th metacarpals as they have longer strides. .

    Moreover, due to the bipedal locomotive  movement of humans,  the joints of a human skeleton  have a smoother and rounder joint surfaces. On the other hand, the joints present in the majority of animals are often more grooved with  a central ridge and have  a better  interlocking shape.

    Long bones of humans also possess great differences from long bones of animals, i.e. the cortical shaft of a human femur and humerus are thinner and the degree of curvature is lesser, while  the femoral head angle  of  a human  is usually greater than 90° as compared to the femoral head angle of an animal which is normally 90°.

    Occasionally, measurements of the bone parameters,  will give a clue on whether the bone is a human bone or not. Driesch and Moore-Jansen produced books on the detailed measurements of  both animal  and human bones. . Theinformation gathered from the measurements can  be taken as a reliable guide  in differentiating the bones when in doubt.

Microscopic Method

Microscopic examination is a  method used especially when dealing with fragmented bones or pieces of remains. Normally, a trained bone histologist  can carry out this examination with confidence.

According to Julie Robert, different species of animals including humans exhibit  different patterns of osteons in the bone histology.

Similarly, Mulhern and Ubelaker mentioned in their research paper  that “the type of osteon banding present in the human and non-human samples are  easily distinguishable between one another.

Bio-chemical Method

Last but not least, DNA analysis is  the definitive method  in identifying human skeletonised remains. Humans possess a certain number and set of chromosomes with  a genetic  makeup which is totally different from any other living organism. Hence, by analysing the  DNA profile, it can determine with a reasonable scientific certainty  that the bone specimen is of human or non-human. .

In  conclusion, one should  not hesitate to consult an anthropological scientist/expert  or request  for further bone analysis when in doubt  during the process of examining and identifying the skeletalised remains.  particularly in dealing with fragmented bones pieces as any mistake will affect the professional service and justice system. .

Differentiating Human Bones With  Artefacts

Besides animal bones, artefacts is another common factor in causing confusion to the  anthropologists in the identification of human bones. For  example chinawares, synthetic polymers, glasses andwood like twigs or tree barnches can be deceiving and look almost similar to bones. Nevertheless, these artefacts can  easily be singled out from actual bones by naked eye appearance as the  surface textures and morphology  are  different from bone tissues. If one  lack  confidence in differentiating bones from artefacts, , microscopic examination  is a valuable  tool to assist in differentiating  between human / animal bones and non-living specimens as the latter will have no bone cells displayed.

References

  1. http://medical-dictionary.thefreedictionary.com/bone
  2. White, T.D., Folkens P.A., The Human Bone Manual, 2005
  3. (2) Bass, W., Human Osteology: A laboratory and field manual 5th edition, 2005
  4. (3) Robert, J., PPT: Forensic Anthropology, 2014
Last Reviewed : 19 May 2015
Writer : Chong Sin Leng
Accreditor : Dr. Nurliza bt. Abdullah