Thick lips in cichlids feature a unique proteoglycan-rich layer that enhances connective tissue volume, contributing to their plump appearance.

Ecologically, bulky lips provide advantages for foraging, allowing cichlids to probe rocky crevices and enhance sensory contact with their environment.

Cichlids from these lakes exhibit similar lip traits despite not being closely related, demonstrating parallel evolution driven by environmental pressures.

The development of large lips is polygenic, influenced by multiple genes and environmental factors, resulting in variability in lip size among different cichlid species.

Gene expression differences related to lip development are established early in juvenile cichlids, indicating that the basis for lip hypertrophy is set early in life.

This research also highlights connections between cichlid lip structure and human conditions, such as keloid scars, where similar proteoglycans contribute to excessive tissue growth.

Dr. Nagatoshi Machii from the Tokyo Institute of Technology leads the study, focusing on tissue composition, gene expression, and lip structures in cichlid species.

Researchers are investigating the evolution of thick lips in these cichlids to understand the molecular basis behind this distinctive trait.

Lakes Victoria, Malawi, and Tanganyika provide unique natural laboratories for researchers to study evolutionary patterns among African cichlids.

Changes in the Wnt signaling pathway, crucial for growth and development, are observed in cichlids with oversized lips, suggesting ongoing gene activity throughout their life stages.

Future research aims to explore genetic loci influencing lip thickness and the parallels between cichlid lip traits and human connective tissue conditions, potentially revealing new insights into tissue growth mechanisms.