Anew study has found that children who look and smell like their fathers tend to receive more paternal investments than kids who do not resemble dad.
The study, which included 30 Senegalese families, has provided the first direct link between a father's investment in his children and his physical resemblance to them.
Alexandra Alvergne, a biological anthropologist at the Institute of Evolutionary Sciences in Montpellier, France, who led the new study, did not know the paternity status of the 60 children involved in the study, but she guesses that a couple of them could have been illegitimate, reports New Scientist.
In order to find which children looked and smelled most like their fathers, the research team systematically involved more than 100 people from a distant village, who were not familiar with the kids.
To reach the conclusion, the "raters" were asked to match a child's digital image to an image of one of three potential fathers. For smell, villagers sniffed a T-shirt the child had worn for a night and compared it to T-shirts worn by two potential fathers.
They correctly matched the child to the right father based on photos half the time. But only men picked out fathers based on T-shirt smell at rates above chance, the researchers found.
The team next compared these ratings to an objective measure of paternal investment, based on the time fathers spent with each child in a day, a standard psychological questionnaire of father involvement, and a survey of financial and emotional support.
Children that looked and smelled more like their fathers tended to receive more paternal investments, Alvergne and her colleagues found.
Factors such as a child's age, sex, or birth order did not predict fathers' investments, nor did the father's own age or wealth.
The study has been published in Animal Behaviour.