Immigration remains one of the most pressing issues in the world today. We are currently witnessing the highest ever-recorded number of international migrants at 244 million. As a proportion of the world's growing population, however, the number of migrants has remained relatively consistent over the past three decades at around 3%. Indeed, migration has always been a part of human behaviour, with population movements shaping the globe across history and pre-history. However, in public and policy discourse, as well as in science, migration is often framed as an unusual or even pathological circumstance, rather than as a recurring feature across time and space.

Yet to consider migration natural is misleading and dangerous. To gloss over the root causes of population movements is to perpetuate injustice to the people affected by them. We are currently witnessing some of the highest levels of forced displacement on record, with 65.3 million people leaving their homes worldwide. Approximately 21.3 million are refugees, and 10 million are stateless. Globally, people continue to be displaced by various combinations of violence, choice, and circumstance, challenging the conventional relationship between ‘voluntary’ migrants, who choose to cross borders in search of opportunity, and ‘involuntary’ migrants, who are forced to flee in search of physical security. Even those who move voluntarily generally do so because economically violent circumstances have obstructed life chances for them and their families. Rather than either voluntary or involuntary, the causes of migration are complex and fall along a spectrum. Nonetheless, the framing of these causes greatly affects how the host country receives immigrants.

How do these discourses impact science? When migration is viewed as unusual or even pathological, assumptions are carried over into research. For instance, a number of methods and scales have been developed to measure the advantages of acculturation or assimilation of immigrants into a host society. Since there is robust evidence that the health status of immigrants deteriorates after a certain time in a host country, researchers frequently view a lack of acculturation or assimilation as the underlying mechanism. These framings presume some easily delineated collection of ‘cultural’ features, along with the belief that changes in these features are more or less uniform across populations, without taking into account how the reasons for migration impact the process. Behavioural and cultural shifts are viewed as inevitable but rarely as reciprocal — most scales only measure unidirectional change, in other words, they leave shifts in attitudes, behaviours, and practices of the host country unaddressed. This leads to reductionist approaches that exclude critical structural factors contributing to the deteriorating health of immigrants.

How we frame the origins and reasons for migration has enormous social and policy implications.

Inequities in the wellbeing of migrants are instead heavily determined by factors such as exclusionary policies, discrimination and racism, employment in marginal and dangerous jobs, the high cost of health care, inadequate housing, and poor access to transportation and other resources. These conditions emerge from host-country assumptions regarding root causes of their migration, which shape ideas about how deserving of incorporation a particular immigrant group should be. Rather than relying on superficial notions of behavioural and cultural change that rest on static assumptions about intergroup relations and unidirectional advantages of assimilation, we must instead understand the large-scale social and political forces that impact migrants. First, this means understanding the structural reasons behind their displacement; second, it means recognizing the processes of institutional, economic, and political marginalization that continue after they arrive in a new country.

How we frame the origins and reasons for migration has enormous social and policy implications. If migration is viewed as an expected and necessary behavioural response to various forms of violence, we can create good science and equitable policies to address disparities in society. Global patterns of inequality that lead to migration are not based on cultural difference, but are instead rooted in social, political, and economic conditions produced and reproduced by social structures, policies, and institutions. Migration is indeed a usual, frequent, and patterned part of the human experience, but it is far from natural.