The Arecibo radio telescope is constantly being tuned and directed in the search for extra-terrestrial life. Do not humans have the greatest instinct for inquisitiveness of all animals?

Whichever horizon you look towards on this part of the Kenyan Rift Valley, the cradle of human beginnings, there is now no obvious sign of human life. Yet seconds after this photograph was taken, the mobile phone in my left trouser pocket rang Richard Dawkins's office from Oxford was on the line.

The toughness of life on the African savannah meant that calorie-rich, high-fat food was at a premium. It has left a craving for some unhealthy foods.

As many paintings and suits of armour of the period show, size certainly counted in the sixteenth century. Was this outfit worn by the Duke of Urbino (1503-72), painted by Agnolo Bronzino, intended to attract the ladies or to intimidate his male competitors.

I spent many sleepless nights wondering about this drake. Faced with such a well-endowed partner, it wouldn't be surprising if the female complained of occasional headaches.

Each of the T-shirts inside these jars was worn for two nights by a female undergraduate and then smelt blind by me, after which I ranked them in order of appeal. Craig Roberts of Newcastle University knew the girls' tissue type and scored these in order of their compatibility to my own. A score of 6/6 signified the closest match and 0/6 no tissue compatibility at all.

A legacy of the Battle of the Somme in 1916, there are thousands of graves like these near Arras, filled with bodies so mutilated that the dead cannot be identified. What instinct is it that leads men to senseless violence of this kind with the protagonists on both sides sure that they are in the right?

The record of my testosterone level - taken every ten minutes during the England-Argentina World Cup match in June 2002 - shows that it doubled immediately when Beckham scored his famous penalty, and rose again after victory was secured. I bet the England team had even higher levels by the end of the match.

I am certain that I have many genes coding for competitiveness. I'm demonstrating this instinct by fencing with a member of the British Olympic team. Draw your own conclusion about which one is me.

I also have a dominant gene for cowardice, and gave up climbing for this reason some years ago. When doing this climb for the television camera, I spent moments frozen in sheer terror.

This cave painting, from a remote part of the Kimberley, North-Western Australia, is thought to be 5,000 - I 0,000 years old. The prone figures of the dead woman and her infant - presumably signifying death in childbirth - testify that, like us, these people also felt sadness, anger and love, and that their spirituality was deeply ingrained.