The Effects of Water on Life

Most objects become larger as they heat up, so they elongate. That's why you need to have things like a gaps between slabs of concrete on a pavement or small gaps in the couplings on bridges and railway lines. Because these small gaps provide space that allows the metal and other things to expand during hot weather. If water did not expand over this temperature range, lakes would freeze from the bottom up. And it may be much more difficult for life to emerge under such conditions.