How lion-tailed macaques have changed parenting techniques with rising rates of twins

Altruism is a much-debated topic in biological studies, and the prevailing conclusion is that almost all forms of altruism are reciprocal. “So, you’re either helping your kin, or you’re helping a friend who could potentially help you in the future,” says wildlife biologist Ashni Kumar Dhawale.

However, when Dhawale witnessed what seemed to be selfless altruism in the form of alloparenting or allomothering – where a non-related individual provides childcare – among the endangered lion-tailed macaques (Macaca silenus) in Puthuthottam in Tamil Nadu’s Valparai, it became the most incredible experience of her study.

Recounting the experience, Dhawale explains that she studied two mothers with surviving twins and their caretaking behaviour until the offspring turned one. This study was significant for two reasons: first, twins are an extremely rare occurrence among primates, especially lion-tailed macaques; second, the first year of an infant’s life is crucial for its survival, with mothers often investing heavily in their care until they pass this developmental milestone.

Alloparenting has not been observed in the species until now. “They have a long inter-birth interval of three years, so mothers are heavily invested in their infants,” says Dhawale. “This is evident in the way they care for them – they carry the infant and lactate for a...

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