Twins, often considered extraordinary in modern human history, have held significant cultural and symbolic meanings across societies. While they are rare today, with only about 3 percent of live births involving twins, a deeper look into evolutionary history reveals a surprising pattern. Research suggests that twin births were once the standard for ancient primates. This shift, from multiple births to singletons, is believed to have shaped the evolution of primates, including humans, influencing survival and development strategies.

Primate Evolution and Twin Births

According to a report by The Conversation, a study published in Current Biology reveals that early primates predominantly gave birth to twins. Researchers led by Dr. Tesla Monson, Associate Professor of Anthropology at Western Washington University and Jack McBride, Ph.D. candidate at Yale University, reconstructed primate reproductive history using data from nearly a thousand mammal species. The team analysed factors such as litter size, body size and pregnancy duration. Their findings suggest that the singleton trait, prevalent among modern primates, evolved later, marking a significant shift in reproductive patterns.

The Transition to Singleton Births

The report further mentions that the mathematical models indicate that this transition occurred at least 50 million years ago. It was observed that the change coincided with an increase in brain and body size among primates, which required more energy and prolonged care. Singleton births allowed primates to focus on raising larger, more developed offspring. This evolutionary adjustment likely provided a survival advantage, fostering traits such as advanced learning and complex behaviours in offspring.

Twins in Modern Context

Today, twin births have risen in some regions, partly due to medical advancements and delayed childbearing. While twinning poses risks, including premature births and complications, it remains a crucial link to primates’ evolutionary past. Researchers emphasise that understanding this historical context can provide insights into the biological and social dynamics of reproduction. The findings underline the profound impact of evolutionary pressures on shaping reproductive strategies over millions of years.