Discuss the evolutionary explanations of functions of sleep. (24 marks)
The evolutionary theories suggest sleep has evolved because it gives an animal a greater chance of survival when in a dangerous environment. They also suggest that sleep has evolved because it conserves energy and coincides with their eating habits. The evolutionary explanation (also referred to as the ecological approach) is based on the observation of animals in their natural environment. The evolutionary approach to sleep has focused on ecological niches. These refer to the lifestyle of animals, i.e how and where they live, and involves many factors that have been shown to be relevant to sleep. The evolutionary approach states that there are several beneficial consequences to sleep. For example, it allows for energy conservation; it provides a period of time where there is no activity, thus allowing the conservation of energy which is essential for animals with high metabolic rates. Webb suggested that everyday sleep is similar to hibernation - sleep conserves energy at times when it’s harder to get resources (i.e at night time). Meddis suggested that sleep helps keep animals safe. By being quiet and still, they’re less likely to attract predators. However, sleep also makes animals vulnerable to predators if discovered. On the other hand, not sleeping at all would be very dangerous, but as it seems to occur in all animals, it must have an important function - although how much sleep animals have varies. Animals that graze often and must avoid predators less, while predators, that don’t eat as frequently and aren’t hunted, sleep more. There is also the suggestion that the amount of sleep is conditional depending on the requirements of the animal. For example, herbivores, such as horses, rely much upon plants for food (i.e. grass), which is relatively low on nutrients; therefore, they cannot afford to spend much time sleeping as they need to spend more time eating. In contrast,...
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