The truth? Both fur and hair are both—well, hair. Each is made up of keratin, and each grows out of hair follicles. The difference has to do with how each strand behaves. SA: Is hair a defining characteristic of mammals?
NS: Its one of them. Other features that define mammals include producing milk to nourish the offspring. SA: When does hair appear to have arisen? NS: We dont know, because the evolutionary lineage leading to mammals includes many fossil forms going way back in time, and hair, as a rule, doesnt fossilize.
So we cant know whether many of these relatives of mammals from the age of dinosaurs and earlier had hair or not. SA: Are there any impressions of hair in the fossil record? NS: There are very few fossils where there are impressions of anything in terms of soft tissue.
SA: How did hair evolve? NS: I think most evolutionary biologists believe that the evolution of hair is correlated with the evolution of endothermy, or warmbloodednessthe ability to produce internal body heatand hair is a very good insulator. If youre going to spend a lot of metabolic energy heating your body, its more efficient to hold on to that heat and not to lose it to the environment around you. So having hair as a means of insulation is one of the ideas about why we have hair.
Of course, there is no way for us to tell whether hair evolved first and then endothermy evolved, or whether endothermy evolved and then somehow hair evolved.
We really dont know anything about these things. SA: Humans evolved in Africa, along with a lot of primates that are covered with fur. Why did humans lose most of theirs? NS: We dont know. Determining whether dogs have hair or fur is a pretty common question. Most groomers say fur, stating that hair is on humans—fur is on dogs.
Another misinterpretation is that hair will grow forever unless it is cut or damaged, while fur has a growth threshold. Not true. The debate rages on. Still, we just need an answer. Many people also believe that dogs who have hair, instead of fur, are hypoallergenic. This gives pet owners a mistaken point of pride. We sought out to finally put the debate to rest and finally establish the true difference. So, do dogs have hair or fur? Technically hair and fur are the same things.
The truth is there is no chemical difference between hair and fur. Each strand of hair begins at the root whether on a human scalp or in the coat of a dog. Each individual strand goes through a cycle of either growing or not growing. The actual part of the strand that is growing is underneath the skin pushing the hair further along.
The variation of the cycle is different for each animal. In general both dogs and cats have an undercoat, comprised of fur, and a topcoat comprised of longer hairs, but there are plenty of exceptions.
Hairless cats, like the Egyptian Sphynx, only have a short coat of fur on their skin and short-haired dogs like the German Short-haired Pointer, all retrievers, beagles, dachshunds, and chihuahuas only have an outer coat of hair. Here is a link to more dogs that have only one coat of hair.
Surprisingly, all the color in dogs and cats is created from just two kinds of color pigments, a black one and a red one. You may be asking yourself then, how is it that I have a white dog or an orange cat? Well, there are 8 genes in dogs and cats that are responsible for telling cells how much of these pigments to produce and where to produce them.
All the color and pattern variations we see in dog and cat coats are due to the directions these genes are giving cells when the cells are producing hair.
Contrary to popular belief, people are not allergic to pet fur ; they are allergic to a protein found in the saliva and skin of pets. When pets groom, they deposit the protein onto their hair, which, in turn, falls into the environment, comes in contact with people, and creates an allergic reaction to those who are allergic to the protein.
Any skin cells dander that fall into the environment can also be a source of allergies in people sensitive to the protein. When seasons change, dogs and cats shed over a period of three to four weeks.
There is no such thing as a non-shedding dog or cat, but pets with one coat shed less than pets with two coats. Still all hair on animals goes through the four phases of development discussed above. That is to say that it grows, matures, stays on the pet for a period of time, falls out, and is then replaced.
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