Landscape in Oromiya, Ethiopia. Photo: Mhairi Gibson
Landscape in Oromiya, Ethiopia. Photo: Mhairi Gibson

Our study is based on data we collected through household surveys from circa 1200 Arsi Oromo women. The Arsi Oromo are agropastoralists who live in southwestern Ethiopia and primarily rely on cattle rearing with some cultivation of sorgum and maize. We asked about various outcomes related to health, education and marriage for their ~ 6200 children.

We wanted to test whether sons and daughters fared differently, and if there was a son bias in polygynous households. Previous studies have mostly looked at all children together, which means that any costs to one group of children can be concealed. In polygynous households, sons who get investment from parents might themselves grow up to become polygynyous, and generate more grandchildren. But because of female reproduction, a daughter can only have a given number of children, regardless of how much her parents invest in her.

Our results show that children of both polygynous first wives and second order wives have some advantages over monogamous wives. But we can also show that these advantages are a little more complex than previously thought. We could not detect any overall son bias, but the outcomes were sex-specific. This is what we found, in brief:

  • Polygynous first wives had the same level of child survival as monogamous women, but children of first wives did better than children of monogamous women in both these later life outcomes.
  • Polygynous second order wives had lower child survival compared to monogamous wives. But, if the children of second wives survived the critical first 5 years of life, their daughters had a lower age at first marriage, and the boys had the same level of education as boys of monogamous mothers.

Read the full blog post by Caroline Uggla here!