Standard models of planet formation suggest that the average earth would be
1.3 earth masses. Such earths would be very warm and have violent weather.
A large moon is necessary to keep the north/south poles locked into position
for our traditional weather patterns. Planets without a large moon would have
rapid climate changes due to relativity space-time distortions from their star.
This would randomly point the planet's north pole toward the star and its south
pole toward the star every 3 million years. This should speed up evolution for
High CO2 levels, however, may result in a loss of bones and may block the
emergence of animal life on planets. This could significantly reduce the number
technologically intelligent species in the universe.