A unique theory proposed by mathematicians suggests that male mammals’ absence of breastfeeding could be an evolutionary strategy to prevent the spread of harmful microbes.
In Malaysia’s rainforests, the Dayak fruit bat stands out as the only wild male mammal known to produce milk. This peculiarity raises questions about why most male mammals do not engage in breastfeeding despite having the physical capability to do so.
In the 1970s, evolutionary thinkers suggested that the lack of male lactation might be due to paternity uncertainty. Since male mammals cannot guarantee they are the biological fathers, they may lack the motivation to invest significantly in offspring care, including breastfeeding.
Recently, researchers from the University of York proposed an alternative view. Their hypothesis, published in Nature Communications, posits that the microbial community in breast milk plays a vital role in establishing the infant’s gut microbiome, potentially influencing why male mammals do not breastfeed.
The theory illustrates how sharing the milk microbiome from both parents could facilitate the spread of harmful microbes within mammalian populations. Maternal-exclusive breastfeeding acts as a filter, allowing only beneficial microbes to pass to the offspring.
Dr. George Constable, one of the study’s authors from the Department of Mathematics at the University of York, highlighted examples like Azara’s owl monkeys to challenge conventional assumptions. These monkeys exhibit unique parental behavior where males play a significant role in childcare, shifting the narrative on male involvement in nurturing.
Dr. Brennen Fagan, the lead author of the study, emphasized the importance of breast milk in shaping the mammal gut microbiome, a crucial ecosystem aiding health and disease prevention.
The mathematical model underscores the advantage of single-parent feeding, with maternal feeding being evolutionarily favored due to potential microbe transmission during birth and pregnancy.
Dr. Constable noted that this theory aligns with mammalian strategies aimed at limiting harmful element spread, akin to mitochondrial DNA inheritance exclusively from mothers in humans to curtail detrimental mutations.
The researchers clarified that their hypothesis pertains to long-term evolutionary trends in mammals and is not a guideline for individual infant feeding practices.
Dr. Fagan emphasized that their model addresses population-level evolutionary dynamics over extended periods, offering insights into mammalian behaviors and adaptation strategies.
