Episode One, Rules of Engagement, is a guide to finding the perfect mate. A story of bloodshed, lies and deception, it offers advice that's as true in the city as it is in the bush. Choosing a mate is one of the most important decisions a female will make in her life. The success of her babies all hangs on her mate having excellent genes and plentiful resources. But as many of us can attest, appearances can be deceptive. So how does an animal tell Mr Right from Mr Wrong? Getting to first base is not that easy. Two of the biggest challenges are going to be finding the right mate and convincing them to cooperate. And if that weren't enough, it turns out that males and females are looking for very different things... Sperm are tiny and cheap; eggs are enormous and very expensive. The problem with this huge difference is that males are always prepared to give theirs up, whereas females are a lot more reticent. The result is a battle of the sexes, a world of showy males and fussy females.