purring has probably offered some selective advantage to cats
Why do cats purr?
Over the course of evolution, purring has probably offered some
selective advantage to cats. Most felid species produce a "purr-like"
vocalization. In domestic cats, purring is most noticeable when an
animal is nursing her kittens or when humans provide social contact via
petting, stroking or feeding.
Although we assume that a cat's purr is an expression of pleasure or is a
means of communication with its young, perhaps the reasons for purring
can be deciphered from the more stressful moments in a cat's life. Cats
often purr while under duress, such as during a visit to the
veterinarian or when recovering from injury. Thus, not all purring cats
appear to be content or pleased with their current circumstances. This
riddle has lead researchers to investigate how cats purr, which is also
still under debate.
Scientists have demonstrated that cats produce the purr through
intermittent signaling of the laryngeal and diaphragmatic muscles. Cats
purr during both inhalation and exhalation with a consistent pattern and
frequency between 25 and 150 Hertz. Various investigators have shown
that sound frequencies in this range can improve bone density and
promote healing.
This association between the frequencies of cats' purrs and improved
healing of bones and muscles may provide help for some humans. Bone
density loss and muscle atrophy is a serious concern for astronauts
during extended periods at zero gravity. Their musculo-skeletal systems
do not experience the normal stresses of physical activity, including
routine standing or sitting, which requires strength for posture
control.
Because cats have adapted to conserve energy via long periods of rest
and sleep, it is possible that purring is a low energy mechanism that
stimulates muscles and bones without a lot of energy. The durability of
the cat has facilitated the notion that cats have "nine lives" and a
common veterinary legend holds that cats are able to reassemble their
bones when placed in the same room with all their parts. Purring may
provide a basis for this feline mythology. The domestication and
breeding of fancy cats occurred relatively recently compared to other
pets and domesticated species, thus cats do not display as many muscle
and bone abnormalities as their more strongly selected carnivore
relative, the domestic dog. Perhaps cats' purring helps alleviate the
dysplasia or osteoporotic conditions that are more common in their canid
cousins. Although it is tempting to state that cats purr because they
are happy, it is more plausible that cat purring is a means of
communication and a potential source of self-healing.
0 comments:
Post a Comment