A recent study by researchers from the University of Wisconsin-Milwaukee and the Lauer Foundation for Paleontology explores the evolutionary history of hagfish eyes, which exhibit significant simplification over millions of years. Published in Biology Letters, the research analyzes fossilized eyes from three extinct hagfish species, revealing a trend toward reduced size and complexity. The findings indicate that while earlier hagfish had larger eyes with lenses capable of image formation, modern hagfish exhibit highly simplified eyes lacking lenses and pigmentation, covered instead by soft tissue. The study outlines a three-stage process of eye simplification: initial size reduction, loss of image-focus capability, and ultimately, near-total vision loss. This gradual evolution likely occurred in nearshore environments before hagfish adapted to deeper waters. The research provides insights into how sensory organs can evolve to become less functional, suggesting that such simplification may be advantageous as these creatures rely more on other senses.