People choose partners with a similar life expectancy

A 2019 study, led by Prof Albert Tenesa, found that people unknowingly choose partners with similar illnesses and life expectancies.

The research team, based at the University of Edinburgh, say these findings help to explain why long-term couples, who often suffer from the same ailments in later years, can have similar life expectancies

The study examined data from UK Biobank, a major study of genes and lifestyle linked to health that involves over half a million volunteers. They used the data to look at information from the parents of couples. It found that even in-laws shared genetic risk factors for illness and had similar life expectancies.

Many ailments are not visible when people first choose their partners. Due to this, researchers think the finding is most likely a result of choosing a partner with shared lifestyle factors that might contribute to illness. This can include behavioural risks such as liking exercise, smoking or not eating well. 

Our study suggests that humans tend to select partners for behavioural or physical traits that are genetically related to disease and longevity.

Understanding what these traits are will require new and long term studies that follow hundreds of thousands of couples from the moment they meet until later in life when they develop disease.

If you're interested in reading more about the study, you can find the paper, published in 'Heredity', in the below link:

Indirect assortative mating for human disease and longevity