For my last blog, I kind of wanted to take a chance and talk about something that I find very interesting but doubt there is much, if any, research on. In class we have learned about sexual selection and how different species pick mates. One way of doing this is through assortative mating. This is a phenotype-based mate choice. There are two types of assortative mating, positive and negative.
Positive assortative mating is when there is preferential mating between individuals of similar phenotype. This increases homozygosity for one or a few specific traits. This basically means you choose to mate with someone that looks like you.
Negative assortative mating is when there is a preferential mating between individuals of opposite phenotypes. This increases heterozygosity and promotes variation for one or a few specific traits. This is when you choose a mate that doesn't look like you. If you have blonde hair, you look for a brunette mate.
So, what I propose is that there might be a sense of positive assortative "picking" when it comes to picking a dog. Dogs are no longer choosen for what activities they perform. Most people who get a dog as a pet are not looking to take it out to the country and have it chase small game in the open field for hours a day every day. But what people are looking for is a cute little puppy or dog that they find cute and attractive and aesthetically pleasing. So why not want a dog that looks like you?
It is only logical to think that people will be more attracted to a dog that reminds them of themselves. I know that my dog, Jack, has the same personality as my dad. This probably comes from 8 years of living together and being best friends but is it really absurd to think that someone with curly hair might rather have a dog with curly hair than straight hair?
Ok, so this concept is pretty far out there but I think its something fun to think about. I have really enjoyed my time learning more about dog breeding and the history of dogs and how they have evolved from wolves. It was very interesting to find out some of the different controversies there are and to see how dogs are helping us in the field of genetic disorders.
Dogs really do nothing but love on whatever humans are around at the time. There is not better feeling than coming home after a long day to someone that could not be more excited to see you and love on you. Having a dog in my life at all times is a major priority of mine and even if its not a dog, I hope everyone gets the chance to love a pet and see how easy it is for them to love you back because thats all animals want.
A problem people have with the evolutionary pathway from wolves to dogs is that they don't know how breeding for tameness can produce all the variation found in dogs. It is understood that today people breed dogs for their looks. They want the right angle of the ears and the perfect coat, but 1000s of years ago when wolves were beginning the domestication process, those were not what was being selected for but those different looks and styles did inevitably show up. But how?
In Siberia, the Russian geneticist, Dmitry Belyaev, has been breeding less ferocious animals, particularly foxes. He used a process that we have heard about many times before. He would only breed the tamest from every litter. What he wasn't expecting to see though was that after only 10 generations he started to see foxes with ears turning downward, tails turning upward, different coats, and some were even barking. The same changes that occurred in wolves 1000s and 1000s of years ago was happening in his own lab and to foxes! Belyaev knew that he couldn't have been selecting for these genes in his breeding because those genes weren't there to be selected for to begin with!
So what Belyaev then decided to do was test all his foxes for different hormone levels. What he found out was that they all had significantly lower levels of adrenaline. This makes sense because these foxes were the tamest of the tame from 10 generations. The biochemical pathway that affects adrenaline levels is the same biochemical pathway that deals with melanin which shows up and a affects the foxes coat. This goes to show that breeding for tameness helps produce different levels of hormones which leads to a cascade of changes.
Breeding for tameness destabilizes the genetic makeup of the foxes, and by proxy, wolves which is a major factor in how we go the great diversity we have in dogs!
The beginning of Dogs and More Dogs talked about the different theories there are for how and why dogs evolved from wolves. Only about 10,000 years ago wolves were a completely homogenous population (and continue to be homogenous today). Wolves are built for endurance, speed, teamwork, and ferocity. This doesn't exactly sound like the type of animal you would want to invite into your house and try and tame/domesticate for a pet.
How do we get from this?
to this?
The main evolution hypothesis is the "adoption" hypothesis. Obviously no one would try and take in an adult wolf and tame them. So people would capture baby wolves and raise them in their homes as a pet. Or at least they would try and turn them into a pet. For the most part, most of the wolves still would grow up into an untamed adult or they would simply run away from the home before adulthood. This helps show that there was more to the domestication of wolves than just bringing them into a human's house. There had to be a change in the wolves personality and behavior to allow this domestication to occur.
There is a place called the Maya-Wolf Park that has turned raising tamed wolves into a science of sorts to try and help understand the domestication process that occurred thousands of years ago. They take wolf pups from their mothers at an early age and they expose them to human contact for 24 hours a day and 7 days a week. The idea is to socialize the puppies to humans as much as physically possible. The humans who are interacting with the puppies have to be very careful though because it is very easy to reinforce wrong behaviors before you realize you have done it. Socializing the puppies to humans help make the wolves less threatened by human sounds and smells. They want the puppies to trust and befriend the humans, not be afraid of them.
Just simply interacting with the wolf pups is not enough. The next step at Maya-Wolf Park is to only allow the tamest wolves to breed and to breed the tamest together to pass on those genes (whatever genes they may be) that produce a tamer animal. If you repeat this process over and over generation after generation, you end up with a wolf that is truly fundamentally different. You end up with a wolf who really has tameness in its genes.
The problem that some people have with this "adoption" hypothesis is that they don't see what is in this set up for the wolf. Why would the wolf want to go live with humans and be domesticated in the first place? And the answer sounds very familiar to the Russian feral dog article I read. The wolf that is tamer or less afraid of people, and the ones that can interact best with the humans, is the wolf that is most likely to get food from the people. Having a steady source of food and nutrition is a huge advantage for wolves and will allow them to survive to reproductive age better (to pass on their tame genes) than those wolves who have to fend for themselves all the time.
This concept does not explain all the physical differences between wolves and all the variations of dogs we have today (coat colors and sizes and textures) but it does help explain some of the first physical variations between wolves and the wolves that evolved into dogs. Dogs, compared to their untamed wolf ancestors, have smaller teeth and a smaller brain. Having smaller teeth will make humans less afraid of you because its one thing if the wolf doesn't run away when it sees humans but that doesn't help if the human is the one that runs away first. Also, if the wolf doesn't have to chase down and bite its prey to death, it doesn't need as big of teeth to sink into food. by looking at other animals, it is understood that animals who are scavengers instead of hunters don't need as big of brains.
Both the National Geographic article and the Dogs and More Dogs movie talked about the adverse affects that can come from artificial selection and pure-bred breeding.
When dogs started to be bred for their looks instead of their abilities, this lead to more breeding for purebreds, which is usually accomplished through inbreeding, which in turn leads to more genetic diseases and disorders. This cycle can be traced back to Victorian England times when dogs became a status symbol. There was a rising middle class and to show that they had arrived in society, they would get a dog. Showing that you had the money to keep and feed an idle pet was very much a wealth symbol at this time.
This is where the importance of bloodlines started. Only purebreds are allowed in dog shows so knowing the bloodline of your liters are very important. One of the only ways to know for sure that you have a complete purebred bloodline is to introduce inbreeding. Having moms mate with sons, daughters with grandfathers, cousins, aunts, uncles, etc. is an easy way to make sure that good genes stay in the family and you don't introduce any bad genes. The problem is the only genes you are artificially selecting for our physical traits. Without genetic testing there is no way to be sure what bad, deleterious genes that code for diseases you are also passing on to your "perfect" Papillion. You might have offspring with the perfect ears that come out of the head at the perfect 45 degree angle and you might get the perfect head size where the head accounts for 2/3 and the snout for 1/3 but you might also be passing on genes for a fatal disease.
The National Geographic article even suggests that simply becoming domesticated allowed for deleterious mutations, which would have been weeded out in the wild, to become selected for and even advantageous. When people were trying to make new breeds, the more distinct of a dog they could breed the more likely it would become a new variation so breeders would go for single genes that would have a larger impact on the phenotypes, not really be concerned with what is happening to the whole genotype.
In the movie, the Papillion breeder seemed to think that the obvious and simple (to her at least) answer to genetic diseases was to perform genetic testing on the dogs and to simply not breed those dogs that have bad genes. Thinking that all breeders will take the time and the money to do this is a bit extreme.
Although these genetic diseases are sad and unfortunate for dogs, they have an upside for humans. Hundreds of dog diseases have been mapped to mutations in particular genes. Many of these dog genes have human counterparts. Only a few bad genes have been identified for behavioral disorders in dogs. One of these genes is the gene that induces OCD in Doberman pinschers. These dogs obsessively suck on their fur to the point of bleeding. This is simple a bad "side-effect" of breeding different mixtures of dogs.
The movie addressed some different behavioral disorders in dogs including nervousness in pointers to the point of paralysis where the dogs are so scared/fearful/nervous that they freeze and you can move them and they will stay in whatever position you put them in. They are truly like autistic or schizophrenic humans where they simply cannot interact with their environments.
The movie also talks about narcoleptic Dachshunds. It is much easier to study diseases in dogs because they have so much less genetic variation than humans. The movie talked to the researcher who found the specific gene that contributes to narcolepsy in these Dachshunds and he believes that researchers can then find the human homolog gene and start working on new medications.
Something I found really interesting in the movie was that millions of dogs get euthanized a year and a lot of those dogs aren't even "sick". Many people have to give up their dogs or put their dogs down because they are "misbehaving". The movie gave a different view though, one that I like a lot more. It suggests that misbehaving dogs aren't "sick" but the behaviors bred into them are simply a bad match for the life they are asked to live. If you live in a small apartment, you are going to want a dog that doesn't bark too much or shed. So these people go out and buy a dog with a low maintenance coat like a Dalmatian. The thing is Dalmatians can run 30 miles a day and not be tired. They are not apartment dogs. So then when the Dalmatian is too energetic for an apartment, the owner thinks there is something wrong with the dog. I have grown up with retrievers and I know that we have to take them outside and throw a ball or a retrieve every night or else they get really cooped up and go crazy in the house. They are not being bad dogs, they are simply reacting to the instincts in their genes.
This movie really made me think about how much thought and consideration you have to put into what kind of dog you want to get and what kind of lifestyle that dog will be living. To make the best life for yourself and your dog, you need to find a dog that fits into your lifestyle and not your aesthetics.
I watched a PBS Nova movie awhile back called Dogs and More Dogs and have been contemplating how to organize the hour of great information into blogs. What I have decided to do is write one or two blogs solely on the movie and then in one blog tie the movie in to the concept of the Russian feral dogs, and finally another blog that ties part of the movie into a part of the National Geographic article I have not talked about yet. The first part of the movie talked about the specifics of the evolution of dogs from wolves and how there is some controversy over how it exactly happened, which was news to me but not particularly surprising. The middle section of the movie took a closer look at a particular breed of dog, the Saluki, and went in to detail on some particular traits of the Saluki and how they might have evolved. Finally, the movie looked into the evolution of not only physical traits of dogs but the behavioral trait of dogs.
THE SALUKI
The Saluki is more of an unusual breed. It isn't a dog that you hear a lot of people owning as pets but it is considered the "Porsche" of dogs. It is one of the oldest known breeds of domesticated dog and was found in Egypt 1000s of years ago. These dogs started out as "sighthounds" and historically travelled with nomadic desert tribes to hunt.
Some of the main traits of this breed are its long legs, skinny waste, large heart and lungs, and its nose. Its long legs are a huge advantage when hunting and chasing something down in the open desert/field. These dogs can travel 10 feet in a single stride and all four of their feet are off the ground twice during one stride. The Saluki has such a skinny waste so the dog can easily tuck its legs high into its chest when running which allows it to travel farther and faster. The heart and lung in this variation of dog are oversized. This allows for more oxygen to be carried to, and waste to be carried away from, the muscles when this dog is running full speed. Even the nose is shaped and designed to help cool the blood.
In the video, a Saluki owner/breeder was interviewed and she said she wanted to breed the dog to have a longer neck and more muscle definition in the rear. This means she is more likely to try and breed her Saluki with another Saluki with those traits to try and come up with some longer necked and more defined offspring. But 1000s of years ago, when this breed of dog was evolving in Egypt, the Ancient Egyptian pharaohs did not know they were artificially selecting dogs with longer legs, skinnier wastes, or larger hearts and lungs. They were simply rewarding the dogs who did the best at whatever task they were asked to do. The fastest Salukis caught the most prey in the desert, those dogs were then in turn rewarded (usually with food) more than the dogs that were too slow to catch the prey (possibly because of their larger waster or shorter legs), the dogs that got fed more, lived longer and got to produce more offspring. Producing more offspring led to the passing on of their longer and leaner genes, and hence selection of those genes. To think that the Ancient Egyptians knew what they were doing is a little far fetched. They were simply rewarding the dogs that did the best, just like giving gold stars to first graders who do well on tests.
Artificial selection and dog breeding is more of a science today because we are trying to breed dogs for traits that they don't really need to use anymore. 1000s of years ago it was easier to breed for traits (although subconsciously) that produced faster dogs, but today wanting to breed for a more defined dog is going to be harder because the dogs today are not required to do any activity that requires more defined rear muscles, or a longer neck for that matter. It is going to be harder to see what dogs possess the traits for larger hearts and lungs because the Salukis today are not expected to run at top speeds for long periods of time anymore. Artificial selection started out as a means for dogs to be better at their jobs. Today it seems artificial selection seems to be a means to produce the prettiest, most aesthetically appeasing dog.
In one of the interviews in the movie, a dog researcher states that he fantasizes about a time when breeders breed dogs for behavior rather than looks. A day when dogs are bred to be the perfect companion and pet. I would have to agree with him. I love dogs and I think they are all (well most of them) are really cute but through breeding, particularly inbreeding, there are so many new genetic diseases and behavioral disorders that cause problems for pets and people think the only way to fix the problem is to get rid of the dog. If people would stop worrying about having the dog with the perkiest ears or curliest hair and focus on having the perfect life companion, it would be a win-win situation for everyone.
This National Geographic article, with an internet copy attached, looks into the genetic "recipes" that create the 350 or so dog breeds out there. The large array of body sizes, ear shapes, nose lengths, and barking habits make dogs the most diverse animal on the planet. If humans had as much diversity as dogs, the smallest people would be 2 feet tall fully grown (like a chihuahua) and some would be 31 feet tall (like a Saint Bernard)!
The most impressive part of all this diversity is how quickly it came about. There are about 350-400 dog breeds, and most have only been around for a couple of hundred of years. Somehow the variation occurred, occurred fast, and stuck. When it comes to dogs, breeders have pretty much put natural selection into fast-forward by first, combining desired traits from disparate dogs and then, breeding the offspring with the largest hint of that desired trait.
The Dachshund
The demand for a better badger hunting dog led to the artificial evolution of the dachshund, which literally means "badger dog" in German. For a dog better at cornering badgers, breeders used a combination of hounds. The obvious choice was the basset hound, with its stubby legs and long body, and they bred it with a mixture of terriers for speed to chase its prey into a burrow. After a couple of generations, they got the dachshund. Its pliable skin serves as a defense mechanism, it can get bit without significant damage or harm. And the dachshund's long, sturdy tail makes it easier for hunters to retrieve the dog, with a badger in it's mouth, from a badgers burrow.
The variation in the dachshund is only the beginning of the variation found throughout the entire spectrum of dogs. It was once believed, and understandably so, that the morphologic diversity of dogs was mirrored in the canine genome. What researchers have found found though is that it is actually quite the opposite. It turns out that the vast mosaic of dog shapes, colors, and sizes are determined largely by a changes/mutations in just a handful of genes. There are only about 50 genetic switches involved in the breed's distinct appearances. It turns out that the difference between the dachshund's small body stature and a Rottweiler's massive one lies in just a single gene. Even the dachshund's stumpy legs, a mutation known as disproportionate dwarfism or chondrodysplasia, also lies in one gene. Some genes have been specifically identified. Like the gene that determines if a dog has floppy ears, like a basset hound, or erect ears, like a great dane, lies on canine chromosome and is called CFA10.
The wrinkles that give shar pei's their distinct look are in the gene region labeled HAS2.
The Rhodesian ridgeback has a unique stretch of fur on it's back that grows in the opposite direction, hence the name ridgeback. This unique trait lies in a mutational change of gene CFA18.
Genes that govern a dog's coat
This was the diagram I found most interesting in this article. It illustrates, very clearly, the 3 genes that play a role in a dog's coat or fur. The three genes are KRT71 (the blue oval), FGF5 (the green oval), and RSPO2 (the red oval). The normal interaction of these three genes result in a short, smooth coat like that of a labrador retriever, but when one or more of these genes is mutated, there is a variation in coats. A mutation in the RSPO2 gene results in a wire coat and/or furnishings (extended beards and eyebrows) like the Australian terrier. A single mutation in the FGF5 gene results in a long coat, such as a Golden retriever, and a mutation in the KRT71 gene results in a curly coat. There can be multiple mutations though. The bearded collie has a mutation in the FGF5 and RSPO2, giving it a long coat with furnishings. The Airedale has two mutations leading to a curly and wiry coat with furnishings, or the Irish water spaniel who has a long and curly coat. And the Bichon frise has a mutation in all three genes giving it a curly, long coat with furnishings. Even with this simple example, you can start to see how much variation is possible with just a few genes. It is not hard to see that if this concept is expanded to more traits, each with a couple of genes, it is very easy to see how all the variation has been made possible.
The end of the last article I read talked about the feral or stray dogs of Moscow, Russia. It was a very interesting look at the evolution of dogs and the possibility for future artificial selection. I was intrigued so I did a little more look into the topic and found a video clip ABC news taking a closer look at these amazing Russian dogs.
It is believed that if artificial selection and humans were taken out of the equation for the evolution of dogs, that dogs would eventually regress and go back to looking like their ancestor, the wolf. But what about their behaviors, actions, and thoughts? Has something about artificially selecting certain physical traits subsequently affected intelligence? By selecting to breed the dogs that are easily trainable, listen, and obey well, have humans created a smarter dog population in general? Or at least give them the tools to think more like us?
The first thing to note is that the feral dogs of Moscow are not just lost Spots, Fidos, and Rexs. There are not "lost dog" signs hanging up around the city looking for them. These are dogs that were born and raised on the streets. The only thing that has been domesticated about these dogs is their ancestral genes. These feral dogs have lost the distinct characteristics of wagging tails, obey commands, perked up ears, and friendliness that separate domesticated pets from the wolf, but that does not make them a helpless, untamed beast of the wild.
Biologist Andrei Poyarkov has estimated that only about 3% of these feral dogs breed. This creates strong selective pressures that would lead to what he believes is rapid evolution. During his 30 years of research, Andrei has identified 4 distinct types of behavior that the dogs have taken on.
GUARD DOGS: these dogs follow around security personnel and treat them as the alpha dogs of their packs.
SCAVENGERS: roam the city for garbage and scraps. Hardly interact with people at all and prefer to fend for themselves.
WILD DOGS: these are the dogs that have regressed most back into the animalistic behaviors and act most wolf-life. These dogs hunt whatever they can find on the streets.
BEGGARS: named for obvious reasons and the group of dogs that has been the most studied and considered the most "advanced".
In packs of beggars, the alpha dog is not the biggest, strongest, or toughest, but it's the smartest. It is not the dog that can hunt the most food, but the dog that can beg for the most food. These dogs are also called metro dogs. They have learned to use the Moscow subway system to help beg for scraps from the daily commuters. It sounds crazy, and almost impossible, but these dogs know one stop from another. Hard to tell if the dogs recognize the name over the loud speaker, the scent, or recognize the station, but the dogs can tell when they get back to where they got on.
Wilcox, the author of the article, says that there seems to have been a shift in this population from "survival of the fittest" to "survival of the smartest". To me though, this seems to be the same concept. To have a high fitness you have to survive to reproductive again and to survive, especially as a feral dog, you would have to be smart enough to live in the human world but without humans. Being able to cross streets at the proper time to decrease the chances of getting hit by a car is one of the adaptions these dogs have made. In both the video and the article, it talks about dogs being spotted at stop lights at cross walks waiting for the light to turn green even when there are no humans around doing the same.
The ABC news clip, inserted above, talks about other adaptions and advantages these dogs have learned. A lot of these adaptions have been ways to become better or more efficient beggars. Some dogs know exactly where people are most likely to give them food so they camp out in certain spots every day. These dogs are considered "superior beggars". Dog packs have learned to end out smaller cuter dogs to beg for food to bring back to the pack. They have learned that the smaller dogs are less intimidating to humans. But that doesn't mean the bigger dogs don't pull their weight. Other dogs will come up behind a person who has food or is eating and will bark or growl and frighten them from behind. In doing so, the human would be startled and have a higher chance of dropping some, if not all of their food. These dogs are not worried about getting humans to like them or feel pity for them but simply focused on the task of finding food.
The video also talked about some of the adaptions the metro dogs have made. These dogs are capable of dealing with loud noises and large crowds. These are both situations in which domesticated dogs cannot handle and would probably have anxiety in. These dogs feel safe around large crowds of humans and are definitely not stupid.
Wilcox ends her article talking about wondering if the strong selection for intellect will make the Moscow metro dogs another species all together. If intelligence is going to make this group of feral dogs a new species, can intelligence then be the next artificially selected trait in dogs across the board? It seems that there is every combination of physical traits in dog breeds already, so is the next step to try and make these dogs smarter? Is it possible to make domesticated dogs as smart as these feral dogs or is the environmental pressure of living in a human world without humans what makes these dogs so smart?
In the end, I think these Moscow dogs are truly amazing. It shows that the possibility of dogs thinking like us is possible. There is a possibility for dogs to survive in our world without us and without regressing back to their animalistic instincts. I also think that the idea of speciation being based off of intellect could become controversial. For years it seems, people have justified animals and humans being different is our intellect and ability to think at a higher level. But if we start to make new species based on their higher intellect than their close ancestors, will we then have grounds to only animal test on the dumbest of the populations? Part of me thinks that the majority of the human population thinks that dogs are already their own species so why not just make it across the board and speciate all dogs, not just the smart ones?
