How might life be different on a planet revolving around a binary star system instead of a solitary star?

Answer 1

Aside from the usual day-night cycle as well as any cycle of the seasons, there may also be an additional cycle in which the light and energy reaching the surface would also change quite considerably, if the planet orbits in the plane of the stars' orbit - the two would eclipse periodically and cut down the amount of light reaching the planet. If the planet orbited away from this plane, it is likely such an eclipse would not occur very often, and light levels would remain "constant" i.e. no different to having only one sun.

The effect this might have on life is not easy to determine, since the life there would have developed in those conditions and we cannot replicate them experimentally in any useful length of time. However, in the same way that life on Earth operates under two cycles of light intensity - the day and night, and the seasons' progression - and the temperature and weather changes this creates, life on the planet under binaries would have adapted to having three cycles, which would make their lives somewhat more complicated in the longterm. In an extreme example, a creature might hibernate for 1 year in part of a cycle, then be awake for 1 year, then hibernate again for 10 years and be awake for 10 years after this.