The Effect of Migration on the Composition of Population

By Khushi Gehlawat

Introduction

Migration has always been a central feature of human history. Whether driven by economic opportunity, conflict, environmental change, or social aspiration, the flow of people from one place to another reshapes societies in profound ways. Beyond simple changes in population size, migration substantially alters the composition of populations in both the regions of origin and destination: age structure, sex ratios, educational levels, occupational makeup, cultural and ethnic diversity, and household organization are all influenced. Understanding these compositional effects is crucial for policy makers, demographers, urban planners, social service providers, and civil society, because these shifts drive demand for education, health, infrastructure, social cohesion, and governance.

This essay explores the various dimensions in which migration affects population composition. After reviewing demographic theory and empirical findings, the discussion will examine specific components affected by migration: age and dependency ratios, sex composition, educational and occupational structure, cultural, ethnic, and religious diversity, and household/family composition. The analysis also considers the differential effects on sending (origin) areas versus receiving (destination) areas, and the challenges and implications that arise. Finally, the essay concludes with observations on policy responses and strategies to manage the compositional effects of migration in ways that maximize benefits and minimize costs.

Description

Migration significantly influences the composition of a population by altering its age, sex, occupational, and cultural structure. Since most migrants belong to the young and working-age group, it changes the age distribution of both origin and destination areas. In rural or sending regions, out-migration often leads to a higher proportion of elderly and dependent populations, while urban or receiving areas experience a rise in the working-age population, reducing their dependency ratio. Migration also affects the sex composition—for example, male-dominated migration for employment leaves a higher percentage of women in rural areas, while cities may see a rise in male migrants.

Educational and occupational structures are influenced as skilled individuals move toward better opportunities, sometimes causing a “brain drain” in the areas they leave. Culturally, migration introduces ethnic, linguistic, and religious diversity, enriching social life but also creating challenges of integration and identity. Family and household structures are transformed as well—many families become fragmented, with members living separately for economic reasons. Thus, migration not only changes population size but reshapes its internal characteristics, influencing economic productivity, social balance, and cultural dynamics in both sending and receiving regions.

Conceptual Framework: Migration as a Demographic Process

Migration is one of the three primary demographic processes — alongside fertility and mortality — that shape population change. But migration differs in that it simultaneously affects two populations (origin and destination), altering both where people live and the composition of those populations. Studies such as Migration and its Effects on Population Growth and Composition by Peter McDonald argue that migration influences population size, age structure, and dependency ratios in both sending and receiving regions. CEPAR+1

The compositional impact depends not just on how many people move but who moves — their age, sex, education, skills, culture — and from where to where. For example, migration tends to be age-selective, favoring young adults, often of working age. Sex‐selectivity may favor one gender depending on the migration type (labor migration, family migration etc.). Educational and occupational selectivity further complicate the picture.

  1. Age Structure and Dependency Ratios

One of the most consistent effects of migration is on age structure. Young adults (say, 15–35 years) are disproportionately represented among migrants because they are more mobile and have both the incentive and ability to undertake migration. Track2Training+2Fiveable+2

  • In origin (sending) areas, this outflow tends to reduce the proportion of working-age people, increase the proportion of the elderly and possibly children, thus increasing the dependency ratio (more dependents per working adult). This can slow economic growth, strain local public services, and reduce dynamism.
    • In destination (receiving) areas, the influx of working-age people can lower the dependency ratio, increase labour force availability, and stimulate economic growth. However, it may also raise demands on infrastructure, housing, health, schooling etc.

Empirical studies show that in many developing countries, rural-to-urban migration tends to leave behind aging rural populations, and cities absorb younger, economically active populations. This has implications for planning, e.g., urban areas must provide schooling, health, and employment for many young arrivals while origin areas may face labor shortages or inability to sustain civic services like elder care. Track2Training+1

  • Sex Composition

Migration often changes the sex ratio (proportion of males to females) in both origin and destination regions. The pattern depends on the type of migration:

  • Male-dominated migration: e.g. labor migration, especially in industries such as construction, mining, or when male migrants are more likely to move for work abroad. Many sending regions consequently see a higher proportion of females (or women) among the resident population.
    • Female-dominated migration: occurs in contexts of marriage migration, domestic work, or migration where women are more active in cross-border or internal moves.

These shifts can have secondary effects: marriage markets may become skewed; caregiving burdens may fall on certain segments (e.g. women in sending areas or elderly dependents). Sex ratio imbalance can also affect social dynamics, potentially contributing to delayed marriage, changes in fertility, and sometimes social stress. Track2Training

  • Educational / Skill Composition and Occupation

Who migrates tends to matter for the human capital composition of both origin and destination.

  • Migrants are often those seeking better education or better jobs, thus the migration out of educated/specialist persons (sometimes described as “brain-drain”) from poorer or rural areas towards urban or foreign centers. In origin areas, the loss of skilled labour can hamper local development, reduce service quality in education or health.
    • Destination areas benefit from the influx of educated or skilled migrants: they add to human capital, fill labour market gaps (especially for specialized jobs), contribute to innovation, entrepreneurship. At the same time, some migrants may only have lower skill levels and take up informal or lower-paid jobs, depending on economic opportunities and credential recognition.

The educational composition of migrants (e.g. proportion having secondary/higher education) impacts how much migrants can contribute. Also, occupational categories of migrants (agriculture, services, industrial, etc.) matter for how the labour market, wage structures, and income inequality may evolve. CEPAR+1

  • Cultural, Ethnic, Religious, and Linguistic Composition

Migration also introduces changes in the cultural, ethnic, religious, or linguistic make-up of destination regions, and sometimes leads to changes in origin regions as well.

  • In destination regions, immigrants bring different cultural practices, languages, religions, festivals, food habits etc. This can enrich the cultural milieu, promote pluralism and diversity. But it can also lead to integration challenges, social tensions or identity politics if not managed well.
    • In origin regions, out-migration of particular ethnic, linguistic or religious groups may reduce diversity or shift the balance among groups.
    • Additionally, migrant flows may cluster by origin, leading to the formation of diaspora or enclaves in the destination, which may preserve cultural traits, but possibly reduce assimilation.

Studies of European countries, for example Austria, show that migration may shift the religious composition or sex ratios within religious groups depending on the origins and gender of migrants. SpringerLink

  • Household / Family Structure

Migration reshapes the composition of households and family arrangements. Several patterns emerge:

  • Left‐behind families in origin areas: children, elderly, or spouses may remain when one or both adults migrate for work. This can alter inter-generational care, household labor divisions, and emotional/social wellbeing.
    • In destinations, many migrants live in new household forms: initially single persons, shared housing, nuclear households rather than extended family structures. Over time, as migrants settle, family reunification or migration of dependents may change these structures.
    • Migration may delay marriage or affect fertility rates: migrants may postpone having children until they settle or due to economic constraints; also, in some cases fertility among migrants differs from the host population (higher or lower depending on multiple factors).
  • Spatial Redistribution and Urban vs Rural Effects

Migration causes spatial redistribution: some places experience population gain, others loss. Rural‐to‐urban migration is a key driver of urbanization. This has compositional effects:

  • Destination urban areas: higher population density, younger populations, more diverse in education, skills, and often more heterogeneous in origin.
    • Origin rural areas: population decline, aging, often loss of productive labor force, possible decline in fertility if young people leave; possibly skewed sex ratios; possibly reduced cultural vibrancy if younger people are leaving.
    •  

Conclusion

Migration does much more than move people from A to B. It reshapes who populates societies: their age, gender, education, skills, culture and family life. In sending regions, migration often drains working-age populations, leaves behind aging cohorts, shifts household burdens, and can reduce capacity for local development. In receiving areas, migration injects youth, labour, and sometimes valuable human capital, but also poses challenges for infrastructure, social cohesion, and equality.

To harness the positives and mitigate negatives, policy responses should be multi‐faceted. These might include:

  • Encouraging balanced migration policies that recognize the need for sending areas to retain or gain critical skills (e.g. return migration, incentives for skilled people to invest in origin areas).
  • Strengthening infrastructure and services in destination areas (housing, health, education, transport) to meet the demands of changing compositions.
  • Enhancing social integration policies to promote cultural inclusion, reduce discrimination, and support migrants’ adaptation.
  • Collecting and using detailed demographic data (age, sex, education, origin) to plan more effectively for future needs.

Ultimately, migration’s effect on population composition is an ongoing and dynamic process. As migration flows evolve in volume, direction, and character (e.g. more female migration, more skilled migration), societies must adapt. Understanding these compositional changes is not just academic — it has real implications for social policy, economic development, cultural identity, and human wellbeing.

References

  1. Donner, W., & Rodríguez, H. (2008). Population composition, migration and inequality: The influence of demographic changes on disaster risk and vulnerability. Social forces, 87(2), 1089-1114.
  2. Harper, S. (2013). Population–environment interactions: European migration, population composition and climate change. Environmental and Resource Economics, 55(4), 525-541.
  3. Plane, D. A. (1993). Demographic influences on migration. Regional studies, 27(4), 375-383.
  4. Migration and its Effects on Population Growth and Composition — Peter McDonald, CEPAR (UNSW Sydney) CEPAR+1
  5. Effect of Migration on the Composition of Population — Track2Training article Track2Training
  6. Impact of migration on population dynamics — Intro to Demographic Methods notes Fiveable
  7. Effects of internal migration on composition by age, sex, education — Latin American & Caribbean demographic studies (ECLAC) repositorio.cepal.org
  8. The Influence of Migration Patterns on Regional Demographic Development in Germany — Ernst et al. (2023) MDPI
  9. The Demographic Effects of Immigration — Australia case study PubMed