Lesson 1 - Determining Ancestry and Sex from Human Skeletal Remains

Distinctions between Human Bone and Animal Bone

Human and Animal Distinctions

If partial skeletal remains are found, especially when no skull is apparent, animal bones may be mistaken for human bones. Distinguishing bones as human or animal may be difficult sometimes.

  1. Ribs: The inexperienced observer might confuse sheep ribbones as human ribs because they are slender and similar in size. However, human rib bones tend to be C-shaped, while most animal ribs tend to be more linear/straight (see photograph below). Humans normally have 12 pairs of ribs. However, some may have one more or one less. Most animals have more than 12 pairs of ribs. Sheep have 13 pairs. (See the photograph below.)

    Animal Rib Bones and Human Rib Bones

    The Ribs of a sheep (left) as compared to human ribs (right).

    - Image Source: Courtesy Julie R. Angel (University of New Mexico, Museum of Southwestern Biology), published in Steven N. Beyers. Introduction to Forensic Anthropology: A Textbook (p. 66). Allyn & Bacon (2002).

  2. Upper arm bones: Human upper arm bones (humerus) are used for lifting and, thus, tend to be smaller and more slender than animal limb bones. This is because humans are bipedal. Bipedal animals move using two legs; thus, the weight of the body is not carried on the bones within the arms. Most mammals are quadrupeds, which means they bear their weight on four limbs when they move.

    In addition, the upper arm bones of a human have a smaller tubercle on the upper part of the bone. This is because a human shoulder joint is less stable because it lies in a relatively shallow shoulder blade. In other animals, the strong ligamentation around the upper part of the limb bones due to larger muscle attachment sites creates a larger tubercle with projections. (See the photograph below.)

    Examples of Upper Arm or Limb Bones

    Deer Sheep Cow Elk Human

    - Image Source: Courtesy Julie R. Angel (University of New Mexico, Museum of Southwestern Biology), published in Steven N. Beyers. Introduction to Forensic Anthropology; A Textbook (p. 68). Allyn & Bacon (2002).

Interestingly, two animals that have skeletal features that are remarkably similar to humans are the North American black bear and the domestic pig.

To the untrained eye, the bones in the paws of the North American black bear can be mistaken easily for human finger bones. Similarly, pig molars appear identical to human molars.

- Source: Steven N. Beyers, Introduction to Forensic Anthropology: A Textbook (p. 67, 71). Allyn & Bacon (2002).

  1. Upper leg bones: The large upper leg bone (femur) of a human has a rounded head with a relatively long neck on its upper region. This head sits within the hip to create a stable joint for movement on two legs. The head of an animal femur is less spherical. A trochanteris located at the same end of the femur as the head. Trochanters are bony bumps to which muscles are attached. In the photograph below, each bone is oriented so that that head in on the left and the trochanter is on the right. Animal bones have substantially larger trochanters due to larger muscle attachment sites and because this joint is positioned more sideways (lateral). These larger muscles and unique joint positioning allow animal movement on all four limbs. (See photograph below.)

    Examples of Upper Arm or Limb Bones

    Deer Sheep Cow Elk Human

    - Image Source: Courtesy Julie R. Angel (University of New Mexico, Museum of Southwestern Biology), published in Steven N. Beyers. Introduction to Forensic Anthropology; A Textbook (p. 69). Allyn & Bacon (2002).

"Crime is terribly revealing. Try and vary your methods as you will, your tastes, your habits, your attitude of mind, and your soul is revealed by your actions."

Agatha Christie (English Detective, Novelist, and Playwright, 1890-1976)

The student will…

  • recognize that in the field of forensic anthropology information about the victim of a crime and the nature of the crime itself is determined from unknown skeletal remains
  • understand that a forensic anthropologist attempts to determine the following information from unknown skeletal remains: whether the remains are human or non-human, number of individuals found, time of death, sex of individual(s), ancestry of individual(s), stature of individual(s), and cause of death
  • describe some of the basic skeletal differences between human and animal bones (such as ribs and upper and lower limbs)
  • state some of the basic skeletal differences between humans from various ancestries or races (such as Negroid, Caucasoid, Mongoloid)
  • identify some of the basic skeletal differences between female and male remains
  • perform a research study that compares the size and length of various bones in males and females

Glossary Term: Ribs

  • Ribs are the long curved bones which surround the chest of land vertebrates, and protect the lungs, heart, and other internal organs

Glossary Term: Humerus

  • The long bone of the arm or forelimb, extending from the shoulder to the elbow

Glossary Term: Tubercle

  • Any small, rounded projection

Glossary Term: Femur

  • Large upper leg bone

Glossary Term: Trochanter

  • A bony bump on the femur (the thigh bone) to which large muscles are attached

Glossary Term: Ligamentation

  • Pertaining to the ligaments, which are thick band of fibrous tissue connecting bones and joints