June 12th, 2010, 09:58 AM
i have a lot of them. so im just going to keep this fairly general and see what you guys have as far as relevant information in regards to
How much of animal behavior is dictated by genetics and in what way?
How much of animal behavior is dictated by environment?
Im hoping someone can show me something new. :-D studies, theories, links...gimme! lol
Great questions, although it may be hard to give a good answer. I don't think that behavior can be split into ..% genes and ..% environment. Try and think about twin studies concerning schizophrenia; identical twins have the same genetic background, but one might develop schizophrenia while the other does not. (There is a hypothesis about monochorionic and dichorionic twins that tries to explain this phenomena, but definitive proof is still not found. Epigenetics is another possible theory.). This means that they both may have a predisposition to develop schizophrenia, but the environment triggers the transcriptions of these genes. The exact environmental factors and the underlying mechanisms are numerous and too complex to take in account.
Here's a place rich with approachable information and links for you to explore:
http://en.wikipedia.org/wiki/Nature_versus_nurture
Nobody can answer these questions. Depends on the species to start with. And even then, we hardly understand human behaviour. We don't understand genes that well either.
How can we ever state with any certainty the % of what is nature and what is nurture.
Even side-stepping behaviour, there is quite a lot of nurture influence in your body as well.
I totally agree. I tried to explain this point of view with the schizophrenia example, but that might have been a wrong approach. But like I tried to explain, a definitive answer is elusive and perhaps even impossible to find.
I understand that a definative answer is not to be found here.
Just looking for any relevant research along those general lines to reflect upon. the question fascinates me. Im a bit of a dog nerd and have done work assisting breeders. they talk a lot about selecting parents based on temperament and as i watch each successive litter develop, i often wonder how much of the careful choosing of parents plays into the behavioral tendencies the pups develop.
musing on the whole thing more..
this is not an idea for an experiment...more of an observational thing...the only goal would be to see what trends might pop up.
the dogs thing. basically i have full access to a closely related population of animals. Including medical records and behavioral records. so far through 4 generations.
i was thinking about starting to keep my own records. the issue is what particulars should i be recording to compile the kind of information that one might use to extrapolate relevant....lines of inquiry...from?
like Im assuming the more detailed the better?
Hauser,
It's a fairly challenging question you're asking. In humans, usually we rely on studies with identical twins as participants to try to determine what traits/characteristics are nature, and which are nurture.
You try to get as many twins as you can, and you have groups of twins who were raised together and you compare them to groups of twins who were raised apart (for example, they were given up for adoption and adopted by different parents... one twin went to one family and the other to some different family).
Then, you compare their behavior, traits, characteristics, etc. When things are really close to the same among the twins who were reared apart from one another, you generally assume it's more closely related to nature than to nurture. That's the general idea, but you need lots and lots and lots of twins who fall into those categories to obtain anything really all that meaningful.
I suppose that with dogs you could track pups who were born to the same mother, and compare skills and disposition among those raised by different humans. When the dogs raised apart have similar dispositions, you'd generally assume that trait is more related to genetics than rearing. Again, though... You'd need a pretty huge population sample to draw any conclusions of merit. Until then, you have only anecdote and limited information feeding your conclusions, so keep in mind that they are less likely to be correct.
Another thing you must bear in mind is how dogs are often bred specifically for certain dispositions, and that is often much more powerful than nurture... those years and years and generations and generations of selection often render nurture moot. Given that, you must remember to check if the particular trait or characteristic you are measuring is something breed specific or not, and try to look at traits which have nothing (or very little) to do with the breed.
Regardless, have fun with it. Cheers.
four litters so far that ive been in attendance for. i have a HUGE population sample though if i can get some of the people i know to let me take notes and have access to their records. that's the cool thing about dogs...the breed i work with dates back to the 1800's. granted the older records are somewhat limited but here's the thing..
each breeder breeds to a "standard" but each has their own interpretation of the standard.
say i start with a single bitch and one litter. i track the growth and progress of said litter..two bitches out of the litter go to other breeders and one male stays with the dam's breeder to be used at stud. i could see how closely the traits they select for align with the stated goals of their breeding programs. in the breed im talking about..average litter size is about 8 pups. this could possibly get massive really quick.
the point isnt really "an experiment" in the strictest sense..the point is practice in developing observational and critical thinking skills in regards to this type of study.
I understand. Thank you for making sure to clarify, though. My deeper point is that dogs are going to be inherently more impacted by genetics than humans would, as we've been artificially selecting canines for centuries, whereas humans have been naturally selected for millienia.
There are important differences, that's all. It's pretty cool that you are thinking about these deeper, more abstract, questions... As opposed to... something more blunt and sharp like how to merely make a profit off of these pretty amazing creatures.
Cheers, mate.
hey if all else fails Ill have a pretty nice scrapbook of all my little goobers..
question..if the years of artificial selection for temperament does result(and im not saying it doesnt..Im just not taking your stone cold word for it either..though the thought is useful because i didnt immediatly jump to it) in a higher tendency for behavior based in genetics..shouldnt it be easier to eventually isolate the genes responsible?
not sure i worded that exactly right but i think it gets the gist across..
If I understand you correctly, you are wondering... If we accept as true that canine behavior is likely to be more related to genetics and "nature" (than to rearing and "nurture") due to our centuries of artificial selection with them... For that reason, would it be easier to isolate the genes responsible for these behaviors in canines?
I really am not sure, myself. I've not studied genetics, but I'm inclined to think that it would be easier if you could compare their genetics to a group of a canines lacking that behavior/disposition than it would be to compare animals with more naturally selected traits over greater expanses of time. I'd be curious to find out from someone, myself.
the thought went something like this...Originally Posted by inow
if behavior in artificially selected animals is more likely to be a product of genetics, then it follows that there is a lower percentage of environmentally conditioned behaviors. if there is a lower percentage of environmentally conditioned behaviors, there should be less need to focus on identifying conditioning stim.
i dunno...just kind of rambling thoughts...its a huge question and everytime i get one of the little subquestions answered, ten more pop up lol.
Try to remember, it only follows if the artificial selection was done specifically for that behavior or disposition. It's not artificial selection itself which is the important factor, but instead the object/trait which was artificially selected.
If the animal was artificially selected to have large testicles or a soft smooth coat, or to be immune to noxious odors... That artificial selection would have little or no impact on the behavior and disposition questions you are asking. Even though artificial selection took place, it would NOT follow that there would be a lower percentage of environmentally conditioned behaviors.
Sorry if I'm coming across as a bit pedantic. Precision is hugely important in science when asking these types of questions.
pedantic is fine. i prefer people to point things out to me whether ive missed them or not..just in case i did miss them.Try to remember, it only follows if the artificial selection was done specifically for that behavior or disposition. It's not artificial selection itself which is the important factor, but instead the object/trait which was artificially selected.
If the animal was artificially selected to have large testicles or a soft smooth coat, or to be immune to noxious odors... That artificial selection would have little or no impact on the behavior and disposition questions you are asking. Even though artificial selection took place, it would NOT follow that there would be a lower percentage of environmentally conditioned behaviors.
Sorry if I'm coming across as a bit pedantic. Precision is hugely important in science when asking these types of questions.
anyways im going to have my morning zombie, stew on some thoughts and come back later..
There was an item in Scientific American a few years back about identical twin studies in humans and what it tells us about the development of human behaviour. The authors concluded that, as an overall generalisation, about 50% of human behaviour is genetically determined, and 50% environmental.
Now, this is not cast in concrete, and the authors could be wrong. It is also not applicable to dogs.
However, it may be a starting point for your questions. If human behaviour is 50% genetic, then dog behaviour will be more so.
Some interesting and relevent work was done by Russian scientist Dr. Belyaev. He bred silver foxes - a totally wild animal - to make them tame. The results were astounding, with silver foxes becoming very much more like dogs. You may care to read up on this.
http://mammals.suite101.com/article....the_silver_fox
i wonder what would happen if he tried to reverse the process....because if you take a bunch of domestic dogs and allow them to breed willy nilly...you dont get a wolf...you get something that looks a lot like a dingo. the mating cycles dont revert to being seasonal like a wolf, the appearance is markedly different than a wolf and the pack behavior lacks the rigid structure and formality of a wolf pack. i wonder what would happen with these foxes..
there was something else i found. something about how a researcher monitored oxytocin levels in both humans and dogs during interaction and they found that the spike in oxytocin in both human and dog mirrored that of a human mother and her child. Im going to try to find it again..
The only problem being that twins share the same environment for 9 months and these 9 months are very influential nurture wise.
So twin studies are used in these studies, but unfortunately there is no exclusion of nurture in these studies.
What an excellent point. Thank you.
The problem of sharing the pre-natal environment is well understood by researchers. As a result, twin studies usually use fraternal twins as the control group. Identical twins are the experiment. Fraternal the control.
Both share a pre-natal environment, so this removes that influence from the experiment.
That is slightly silly isn't it because the womb isn't a static environment. You can't really compare two wombs. So there cannot be controls as such. Unless you start with the hypothesis that a womb is a womb and always the same.
fraternal twin datapoint 1. Mother got shitfaced drunk during vulnerable stage of fetus development.
identical twin datapoint 2. Mother didn't get shitfaced drunk.
Datapoint 1 cannot act as a control for datapoint 2. Although technically it might be used as a control. It's merely the handicap of doing experimentation on humans. You have imperfect methods because of ethical considerations.
How do we do it with mice? We create transgenics and cross it so that the litter contains mice that are homogeneous for the modified gene, and use the heterozygous mice as a control or the homogeneous wildtype in the same litter.
It's actually quite funny because often you read wildtype control in the paper and it turns out they are all heterozygous, which means one inactive/active allele.
Identical and fraternal twins can only be used as a control when assuming very generous levels of similarity between two cases. And we do that because there is nothing better. It isn't a proper control though.
I disagree as well; with fraternal twins, the apparent differences in appearance results in nurturing differences. Those nurturing differences diffuse what fraternal twin might have acquired in the womb. With identical twins, the nurturing received in the womb is aroused or reinforced by the nearly identical treatment twins receive by virtue of their similar appearance. Even when raised apart, their similar appearance and womb inspired behaviors likely arouses similar nurturing from differing caregivers.
SM
You may have missed the point. It is the development of differences between the two members of a twinship that are measured.
Take IQ for example. If the researchers are looking at how much the environment counts for differences in IQ compared to genetics, they look at how much IQ differs in identical twins reared apart. The comparison is fraternal twins reared apart, since fraternal twins also shared a uterine environment. If the mother dosed herself on booze, then it will affect the fraternal twins equally. Ditto for identical.
We know how many genes differ on average between fraternal twins. This permits a calculation to be made on affect of degree of genetic difference on IQ (or whatever other quality is being measured), by comparison with identical twins who share 100% of the same genes.
It's also worth baring in mind that identical twins have a great deal of epigenetic differences - which, to my mind, throws a spanner in the works when trying to draw conclusions from such studies.
I'm sure that was what is meant but it was stated that fraternal twins acted as a control group.
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