The elements any particular animal needs are relatively predictable. They are predictable based on the past: what an animal's ancestors needed is likely to be what that animal also needs. Taste preferences, therefore, can be hardwired. Consider sodium (Na). The bodies of terrestrial vertebrates, including those of mammals, tend to have a concentration of sodium nearly fifty times that of the primary producers on land, plants. This is, in part, because vertebrates evolved in the sea and so evolved cells dependent upon the ingredients that were common in the sea, including sodium. To remedy the difference between their needs for sodium and that available in plants, herbivores can eat fifty times more plant material than they otherwise need (and eliminate the excess). Or they can seek out other sources of sodium. The salt taste receptor rewards animals for doing the latter, seeking out salt in order to satisfy their great need.

Long-term elephant groups are composed exclusively of adult females and juvenile males and females. Elephant leaders are typically chosen from among the oldest females in the group, and this matriarch is relied on to coordinate group movements, migration, and responses to threats, such as lions. The leader's role in these situations is to call the other elephants to action and direct them toward threats or opportunities. She doesn't dash out in front to provide protection (when threatened by lions, all the adults position themselves in front to protect their young); nor does she suffer hardships on behalf of her group. The leadership she provides is in the form of guidance. Because leadership does not give her preferential access to food sources or mating opportunities, elephant leaders do not gain unique benefits from their position.

A patient of mine who is more of an outwardly focused perfectionist feels angry when other people make errors, forget things, misplace objects that he needs, respond too slowly, or give him incorrect information. These kinds of things would probably bother most people, but for some perfectionists these errors feel personal. It can seem as if others are intentionally doing these things just to irritate you. In most cases, these situations are not that simple. They do not involve just the perpetrator (the one who made the mistake) trying to do harm to the victim (the perfectionist). There are usually many other circumstances that influence the situation. For example, the person giving misinformation may be new on the job, may have been misinformed by her boss, may be correct under different circumstances, or may have misunderstood the question. When you oversimplify, none of these excuses matter because you are focused only on the wrong-doing and your upset feelings.

Clearly, bright colours are advantageous for prey defences. But how did they evolve? One possibility is that conspicuous colours evolved first, followed by distastefulness. For example, some brightly coloured birds like kingfishers are distasteful. Their colours may have been favoured for better mate attraction or territory defence and then, because they also increased conspicuousness to predators, this then favoured the evolution of distastefulness. The other possibility is that distastefulness came first. This may apply to those insects, such as caterpillars of the monarch butterfly, Danaus plexippus, which feed on plants containing toxins and incorporate the toxins in their bodies as a defence against predation. It is plausible that here distastefulness evolved first followed by conspicuousness. In this case, then, bright colouration evolves specifically as a warning device.

Leslie doesn't realize it, but she stalled out from her fear of failure. She imagined hundreds of reasons why her ideas might not work, and then used these reasons as legitimate excuses for not taking action. Leslie needed to face up to the fact that she concocted her own reasons for failing to act, and that the development of those reasons, if not grasped and eliminated, could lead to her being stymied further. Leslie functions like many of those who never go forward with their ideas — the professor who never finishes writing his book, the artist who never paints the picture she dreams about and mentions to others, the business person who has a wonderful money-making scheme but never implements it. The fear of failure in these people extends beyond an inability to reach a level of success or a level of perfection. To these people — and Leslie might well be one of them — if their project isn't flawless, if it isn't of Nobel Prize quality, then, in their minds, it's a failure, and they will delay taking action because they cannot tolerate being imperfect.