1 - Going to a family gathering when there's unresolved conflict, whether from months ago or years ago, can be stressful.

2 - Much of the renewed optimism for life on Mars comes from a wealth of data suggesting that, up to about 3.5 billion years ago, Mars was much more like Earth, with large amounts of surface water.

3 - Around 500 million years ago, something awful seems to have happened on Venus.

4 - Life on land probably began about 430 million years ago, though it had existed in the water for perhaps as much as 3 billion years.

5 - Until about 30 years ago, the developing countries of Asia were mainly threatened by infectious diseases, nutritional deficiencies and unsafe pregnancies, resulting in a huge burden of death and disability in childhood and early adulthood.