What if humans were nocturnal?

If humans were nocturnal, the implications would be far-reaching and would affect various aspects of our physiology, behavior, and society.

Physiological Changes

• Vision: Nocturnal humans would likely develop larger eyes and wider pupils to capture more light in the dark. They would also have a reflective layer in the eye called the Tapetum lucidum, which amplifies light entering the retina, causing the eyes to glow in darkness. The retina would contain more rods than cones, enhancing the ability to detect light sources but potentially reducing color vision12.
• Other Senses: The lack of light would lead to heightened senses of hearing, smell, taste, and touch. This could result in more mobile ears to track sound, longer snouts for smelling subtle scents, or fibrous skin to feel vibrations and movements. Nocturnal humans might also develop thermal vision, echolocation like bats, or an extraordinary number of taste buds12.

Behavioral and Social Changes

• Activity Patterns: The most immediate change would be that humans would do most of their work at night and sleep during the day. This would reverse many of our current daily routines, with shops opening at night, schools and offices operating from evening to midnight, and social events like parties and raves happening during the daytime12.
• Lighting and Technology: There would be a significant reduction in the need for artificial lighting. Street lamps and car headlights might become obsolete or even hazardous, as they could interfere with the enhanced night vision and other senses of nocturnal humans12.
• Living Environments: Nocturnal humans would prefer cooler, nighttime temperatures, leading to a shift in air conditioning needs and a reduction in the importance of sunlight for heating. This could also influence architectural and urban planning, with living environments adapted to be less vibrant and more conducive to nighttime activities12.

Societal and Ecological Impact

• Work and Leisure: Daily routines would be flipped, with nightlife becoming daylife and vice versa. This would affect various industries, including agriculture, which might rely less on traditional work animals like horses and cows due to the lack of sunlight12.
• Impact on Other Species: The natural world would need to adapt to humans being active at night. Many nocturnal animals might shift to diurnal lifestyles to avoid human activity, while animals closely associated with humans, like dogs, might also adopt nocturnal behaviors12.
• Navigation and Communication: Nocturnal humans might develop alternative navigation methods, such as using the night sky or echolocation. They could also develop bioluminescence for communication or attracting mates, similar to fireflies and glowworms12.

In summary, if humans were nocturnal, it would lead to profound changes in our physical characteristics, daily behaviors, social structures, and our interaction with the natural world. These changes would be multifaceted and would have significant repercussions on nearly every aspect of human life and the ecosystems we inhabit.