I noticed that my cat which is only 6 months old has started stretching its body from time to time. Then I thought that this motion doesn't seem very natural from another cat's viewpoint, so my cat probably didn't try to imitate some other cat all of a sudden and learned it like that. This action must have been caused by something else then. Or at least that's what I think.

Both animals and people stretch their muscles from time to time, but it doesn't seem to be caused by memory of others doing it. So how does this action originate in them?

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    $\begingroup$ stretching also occurs in animals that wake up and when yawning. $\endgroup$ – CognisMantis Nov 20 '14 at 21:26
  • $\begingroup$ Stretching is usually accommodated with a yawn in humans & animals. This is because when we are tired & sleepy, our breathing patterns slow down, letting half of the oxygen we normally breath in slow down to a minimum rate. When we wake, our body's suddenly needs to pull in a high amount of oxygen so we can function at full energy levels/ being alert. When we yawn, we pull high volumes of oxygen into the lungs which distribute it throughout our blood stream. When we stretch, this allows the oxygen breath in while yawning to flow throughout the body faster. $\endgroup$ – user17608 Aug 31 '15 at 19:29

Humans and other animals have lots of innate behaviors that are not learned from observation, i.e. behaviors that are hard-wired into our nervous system, and this is one of them. Suckling reflexes in mammals and the Moro reflex is human babies (which we grow out of) are other simple examples.

The stretching behaviours you are referring to are usually labelled pandiculation in humans (defined as involuntary stretching of the soft tissues), and yawning is often considered a special case of this. These kinds of behaviours are also normally related to transition periods between high-low activity in animals (Walusinskie, 2006). In practice, stretching functions as a way to reverse the muscular atonia during REM sleep, and is in this sense a way to restore homeostatic functions (Fraser, 1989; Walusinskie, 2006).

A paper by Rial et al (2010) deals with the evolution of sleep and wakefulness in mammals from our reptile predecessors, and indicates that stretching behaviours might have originated/evolved from post-basking activities, more specifically risk-assessment behaviours, such as:

...risk assessment behaviour (RAB) and consists of the suspension of current behaviour, to be replaced by head dipping movements, eye scanning, rearing and adopting stretch attending postures...

There is most likely much more to be said about this, and the paper cited above contains many references that can provide further clarification and evidence. A short comparative discussion of pandiculation is found in Frasier (1989).


protected by Chris Oct 16 '16 at 18:04

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