3 Factors that Affect Anatomical Variation

Learning Objectives

  • Explore factors that contribute to variation in anatomical structure.

The presentation of phenotypes in an individual or across a group of individuals has been shown to be affected by a number of factors including ancestry, sex, secular change, population variation and socioeconomic status. In this chapter we introduce each of these factors and provide examples of how these factors influence anatomical variation.


An individual’s ancestry is defined as one’s familial descent, and results in anatomical differences due to many factors, including genetics, population origin and social constructs. Evolutionary processes such as natural selection, genetic drift and mutation, and gene flow, lead to the development of phenotypic variation between different human populations (Christensen et al., 2019). If you were to look around a crowd of people, which for example is composed of native Nigerians, native Japanese and native Scottish people, you would be able to note from their soft tissue facial features whether their ancestry was African, Asian or European; equally the morphology of their skull is also variable (White et al., 2012). It is important to note that the term ‘ancestry’ should be used when examining human variation, and the term ‘race’ should be avoided due to the problematic history of racism and the word having different meanings to different people.

In an Australian context, the forensic anthropological estimation of ancestry is essential to establish whether a set of human remains are of Aboriginal or Torres Strait Islander origin dating prior to the period of European contact, which are protected under the Aboriginal Cultural Heritage Act 2003 and the Torres Strait Islander Cultural Heritage Act 2003.


Although sex and gender are often used interchangeably in popular media and literature, they are terms with different meanings. Sex refers to an individual’s genetics and biology, while gender is an identity defined by a person’s inner concept of self. The inheritance and expression of sex chromosomes – XX (females) and XY (males) – result in variation in behavioural, physiological and anatomical dimensions (White et al., 2012). For example, anatomical variation is often prominent in some areas of soft tissue as well as within the skeleton. This is largely due to differences in size and structure related to reproduction, parturition (childbirth) and biomechanical functions at joints for locomotion (movement).

In terms of human growth and development, it is known that the developmental rate of females and males differ, and growth rates vary between populations. This variation may be a result of genetics, nutrition, activity level and environmental factors.

Secular change

Changes in growth patterns have occurred over time (Christensen et al., 2019). For example, evidence shows that we are taller now than we were previously (even just a century ago!), and the increase in height is not necessarily proportional to changes in bone length. Additionally, modern populations demonstrate an earlier onset of biological maturation, such as the timing of puberty and bony growth and development. This change in growth pattern over one or more generation is called secular change.

The increase in stature, weight and acceleration of growth and development is attributed to improvements in living conditions, including improved nutrition, improved disease environment and health status, a decrease in physical workload (particularly during childhood) and socioeconomic status.

Population variation

Evidence has shown that growth patterns vary between populations as a result of environmental and social influences. Climate, material culture and population customs are some factors that have been shown to impact on biological age, and therefore necessitates the requirement for population-specific standards. Adaptation to a specific environment and geographical region have also been documented as influencing anatomical variation.

Socioeconomic status

Socioeconomic status refers to the social and economical conditions within a population, and impacts on the development of anatomical variation. For example, genetics may influence the rate of skeletal growth and development, however can be further accelerated by an optimal living environment. Parental income, education, neighbourhood quality and occupation are all measures of socioeconomic status, and have a powerful influence on physical health and an individual’s anatomy, such as brain volume and cortical surface areas.


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Anatomical Variation: An Australian and New Zealand Context Copyright © 2023 by Queensland University of Technology is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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