Dog

Dogs are mammals that have undergone domestication of wolves since 15,000 years ago or may have since 100,000 years ago based on genetic evidence and the fossil discoveries in the form of DNA testing . Other studies reveal that dog domestication history has not been so long
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The dog has developed into hundreds of races with a wide variety , ranging from a few dozen dogs cm height as the Chihuahua to the Irish Wolfhound is more than one meter high . Dog hair color can be varied , ranging from white to black , also red , gray ( often called " blue " ) , and chocolate . In addition , dogs have a variety of hair types , ranging from very short to the length can reach several centimeters . Dog hair can be straight or curly , and coarse -textured to soft as wool.

Science learning anything about the dog named kinologi ( from the ancient Greek κυνός , read kynόs , " dog " and λόγος , logos read , " speech , sense " )

Dog breeds vary greatly in size , appearance , and behavior than other pets . Most of the dogs still have the physical characteristics derived from wolves . Dogs are predators and scavengers , have sharp teeth and strong jaws for attacking , biting and tearing food . Characteristics of a wolf ancestors still survive in the dog , although selective breeding has succeeded in changing the physical form of various types of dog breeds .

Dogs have strong muscles , ankle bones united , cardiovascular system that supports physical endurance and running speed , and teeth for catching and tearing prey . When compared with the bone structure of the human foot , dogs technically walk on tiptoes with your toes .

Vision
Dogs were once presumed dikromatis , so it can be called color blind by human standards .  But research conducted lately it shows dogs can see some colors , although not as can be seen of men.

For dogs , the color is a subliminal signal that is captured to distinguish the shape of the object overlap , and not the color of the objects that can be directly distinguished dog . According to the study , the dogs can see various shades of yellow , purple or violet , ulta violet .

Dog eye lens is flatter than the lens of the human eye , so the dog can see in detail less than human . Instead , the dog 's eyes more sensitive to light and motion than the human eye . Some dog breeds , has a field of view up to 270 ° . By comparison , humans have only 180 ° field of view . Race with a field of view of the dog 's head and eyes wide in front is actually almost the same as humans , only about 180 ° .

The sense of hearing [edit | edit source ]
Dogs can hear sounds of low frequency 16Hz to 70 KHz . ( People only hear the frequency of 20Hz - 20 KHz ) , including the total width of this frequency is quite good , but still less than hearing cats . [ 10 ] In addition , dogs can move their ears in order to quickly determine the exact location of the sound source . More than 18 muscles in the ear allow dogs tilt , twist , tuck , or enforce earlobe . Dogs were able to determine the source of sound faster than humans , and can hear sounds four times farther source that can be heard humans . Dogs with naturally shaped ears ( erect ears like a wolf ) usually have better hearing than dogs ear leaf falls such as found in many species the result of domestication .

The sense of smell
Dogs have nearly 220 million olfactory cells are sensitive to smells . It was about as wide as a handkerchief , a very wide when compared to that of the human olfactory cells . For comparison , humans only have 5 million olfactory cells which occupy an area as wide as stamps . Some types even intentionally bred purebred puppy that was born with a better sense of smell . Collection mechanism in the brain information is based dog odor particles wrote about is not known clearly . According to the study , the dogs can distinguish two types of smell : the smell in the air particles are spread from person or object , and odor particles in soil can still be detected after some time . Characteristics of the two types of particles seems to be quite different smell . Scent particles in the air are easy to lose , but maybe not so obvious and mingled odors of other , whereas the ground scent particles in relatively more permanent . Dogs must be persuaded to do it again and again and be careful , because the smell is embedded in the ground easily contaminated by other odors .

Bloodhound trainer already understand that the dog is no longer possible to track taught odors over natural ability possessed from birth . Dogs can only properly motivated and taught to concentrate on the main trace of odor . Trained sniffer dogs should be able to ignore the smell of other traces . Dogs that are not trained are usually happy to sniff various odors in addition to a wide trail of scent that was ordered . When do the grueling work for dogs ( eg search for contraband goods on board ) , the dog must be motivated to want to work hard in a long period of time .

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