Study: Nearby Exoplanets Likely Stuck at Microbial Stage

A study in the International Journal of Astrobiology links the evolution of complex life on exoplanets to cumulative photosynthesis rather than time alone. Of 29 nearby exoplanets that could hold liquid water, only GJ 1061c and K2-3d might have surpassed Earth's evolutionary stage, while TRAPPIST-1e likely remains microbial.

• Only 2 of 29 nearby exoplanets may have out-evolved Earth
• TRAPPIST-1e fixed just 21% of Earth's total carbon
• Earth fixed 2.4 × 10²⁵ g of carbon before vascular plants
• Rainfall is the main constraint on plant growth on exoplanets