Scientists claim to have found answer to centuries-old puzzle, ‘What came first: Chicken or the egg?’

A recent study claims to have finally answered the age-old question that has puzzled humans for centuries: which came first, the chicken or the egg? The scientists conducting the research assert that they have discovered the solution to this perplexing enigma.

According to the University of Bristol researchers, the ancestors of reptiles and modern birds likely gave birth to live offspring instead of laying eggs, as reported by The Times. The study, published in the Journal Nature Ecology and Evolution, provides detailed insights into this groundbreaking finding.

Contradicting the previously held belief that hard-shelled eggs were crucial for the success of amniotes (animals whose embryos develop inside an amnion within the egg), the scientists, in collaboration with Nanjing University researchers, challenge this notion.

The study elucidates the stark differences between amniotic eggs and anamniotic eggs found in present-day amphibians, which lack an eggshell and extraembryonic membranes. The amniotic egg comprises fetal membranes like the amnion, chorion, and allantois, along with an external shell that can either be highly mineralized (as in rigid-shelled eggs) or weakly mineralized (as in parchment-shelled eggs).

To arrive at their conclusions, the University of Bristol’s School of Earth Sciences led the research, examining 51 fossil species and 29 extant species categorized as either viviparous (giving birth to live young) or oviparous (laying hard or soft-shelled eggs).

The study underscores the observation that all branches of Amniota, including mammals, exhibit signs of embryos remaining within the body for longer durations.

Traditionally, the hard-shelled egg has been regarded as one of evolution’s most remarkable achievements. However, this study posits that extended embryo retention, rather than the presence of a hard shell, provided the ultimate protection for this group of animals.

Professor Michael Benton from the University of Bristol commented on the study, stating, “Our work, along with that of many others in recent years, has invalidated the traditional ‘reptile egg’ model found in textbooks. The first amniotes developed extended embryo retention rather than a hard-shelled egg to safeguard the developing embryo for a varying period inside the mother, allowing birth to be delayed until more favorable environments arise.”

Project Leader Professor Baoyu Jiang added, “In some cases, closely related species exhibit both behaviors, and it turns out that live-bearing lizards can switch back to laying eggs more easily than previously believed.”

In summary, this groundbreaking research has challenged long-held beliefs about the significance of hard-shelled eggs in amniotes’ success, highlighting the role of extended embryo retention in ensuring the survival and development of these animals.