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  #1  
Old 02-04-2011, 10:45 AM
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I still don't get it: Why do different people have different personalities?

Ok, this is basic perhaps, but I was reading about personality tests and personality types (conscientious, dramatic) disorders (borderline), but then i thought: Why do (different) people each have different personalities?

Why don't we all have the same type of personality? Did we evolve this way randomly and it happens to help us because of personality 'diversity'? Then why did we evolve having bad things like borderline personality disorder?

I don't get it. (Just to clarify I am asking why each individual person has their own personality; I'm not mentioning something like 'multiple personality disorder')

Last edited by No Wikipedia Cites; 02-04-2011 at 10:45 AM..
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  #2  
Old 02-04-2011, 11:21 AM
Alka Seltzer Alka Seltzer is offline
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The short answer is evolution. We are genetically distinct from each other. We are also shaped by our life experiences. If you take two identical twins, and raise one in a caring environment, and the other in an abusive environment, they will turn out very differently. We have the ability to learn.

Diversity is a good survival strategy. It helps prevent a species from being wiped out. Variation in physical characteristics and behaviour are required to overcome different environmental conditions. A race of identical clones might be extremely vulnerable to loss of a food source, climatic change, or a particular disease.
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Old 02-04-2011, 11:22 AM
Rigamarole Rigamarole is offline
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Nature and nurture, of course. Growing up in vastly different environments affects the way people interact with the people and things in their surroundings. Over time this leads to hard-wired genetic differences, which also influence any particular person's personality.
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Old 02-04-2011, 11:24 AM
Duckster Duckster is offline
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WAG. Human beings are not clones or each other, nor are they created, raised and nurtured in identical environments. In the bluntest of descriptions, as biological units we are are all different from each other by just that much. Add in the randomness of cell divisions from conception onward and chemical combinations and reactions that go on in your body (and brain) are not the exact same as anyone else.

I'm sure the experts will be along shortly and either blow this WAG out of the water, agree with it, come up with something else, or recombine similar thoughts. You know, kinda like what I just said.
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Old 02-04-2011, 11:30 AM
Grey Grey is online now
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It's like asking why all trees don't have the same branch structure. Of course the general shape is there but the interplay of the environment and genetics leads to difference.

Add in the cultural aspect and human's ability to shape their own personalities and you're bound to get a spread in how people behave.
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Old 02-04-2011, 11:32 AM
Gary T Gary T is online now
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A branch of humans where all had the same personality wouldn't last long. There are times where survival depends on being daring and aggressive, and other times where it depends on being circumspect and cautious. In a group with a mix of personality traits, the daring can pull the others along when they're being too timid, and the careful can hold back the others when they're being too brash. In a group where all are the same, the time will come when they all will fail.
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Old 02-04-2011, 12:04 PM
ITR champion ITR champion is offline
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Quote:
Originally Posted by sassyfras View Post
Ok, this is basic perhaps, but I was reading about personality tests and personality types (conscientious, dramatic) disorders (borderline), but then i thought: Why do (different) people each have different personalities?
A world where everyone had the same personality would be no fun at all.
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Old 02-04-2011, 12:11 PM
tdn tdn is offline
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With all of our differences, we're still more alike than different. That's kind of astonishing to me.
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  #9  
Old 02-04-2011, 12:21 PM
Lasciel Lasciel is offline
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Really basic answer in the form of a question (and be honest) - Would you want to procreate with an identical personality clone of yourself?

If you do, I think you're in a pretty limited crowd.

Phrases like 'opposites attract' exist for a reason.
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  #10  
Old 02-04-2011, 12:34 PM
Zsofia Zsofia is offline
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Even fish have different personalities. It seems to be fairly universal in higher vertebrates.
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  #11  
Old 02-04-2011, 12:53 PM
Blaster Master Blaster Master is offline
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Originally Posted by Alka Seltzer View Post
The short answer is evolution. We are genetically distinct from each other. We are also shaped by our life experiences. If you take two identical twins, and raise one in a caring environment, and the other in an abusive environment, they will turn out very differently. We have the ability to learn.
I agree, but this seems more like a nurture argument than a nature one as your openning sentence would imply. To take it a step farther, if we take two identical computers programmed with identical learning algorithms and even their random number generators are seeded identically, given different data, what they learn will be somewhat different. Over the course of billions of trials, as we have with humans, there will be sufficient variation that learned behaviors will differ.

I think the more interesting part here is that, by and large, we actually do have a lot of common learned behaviors. For instance, the vast majority of people have roughly similar ideas of a moral code and general ideas of some tendencies intrinsic to their cultures. It's like when we compare someone with a genius level IQ to someone with a very low IQ and we focus on how different their level of intelligence is, but compared to any other species, their relative intelligence is actually pretty darn similar.

Quote:
Diversity is a good survival strategy. It helps prevent a species from being wiped out. Variation in physical characteristics and behaviour are required to overcome different environmental conditions. A race of identical clones might be extremely vulnerable to loss of a food source, climatic change, or a particular disease.
Inevitably there are variations in genetics and we're not identical. If we'd evolved to have identical personalities, it's probably also pretty likely that we'd also have evolved to all have the same skin, hair, eyes, build, etc. Evolution doesn't operate in a manner that results in some idealized version of a species, it simply selects for those that do well in passing on their genese and against those who do poorly, which means things that don't have a whole lot of effect either way, like some personality differences, are going to stick around. Even particularly bad genes can stick around, or particularly good ones can disappear, under various circumstances.

Again, the part I find interesting is that we are in fact so remarkably similar, with well over 99% of our genes being identical. Overall, even our inherited behavior is remarkably similar as social creatures, speech, family structures, etc. and yet we still find the differences we do have and they appear rather larger than they are.
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  #12  
Old 02-04-2011, 12:54 PM
Pleonast Pleonast is offline
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Our personalities are not that different, but our brains are specialized to distinguish small differences. The variety is in the perception. It's like faces--our faces are all pretty much the same, but we focus on the subtle differences.
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  #13  
Old 02-04-2011, 01:09 PM
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Originally Posted by Pleonast View Post
Our personalities are not that different, but our brains are specialized to distinguish small differences. The variety is in the perception. It's like faces--our faces are all pretty much the same, but we focus on the subtle differences.
What about the personality of a psychopath vs a saint?

Or a neurotic versus a stoic? Would not a dumb dog tell the energy difference between Woody Allen vs Gary Cooper?

Aren't those quite different?

Extreme examples, but there must be several million (10s of millions?) personality disordered people in the US alone.
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Old 02-04-2011, 03:12 PM
Alka Seltzer Alka Seltzer is offline
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Originally Posted by Blaster Master View Post
I agree, but this seems more like a nurture argument than a nature one as your openning sentence would imply.
I could have phrased it better. We start off genetically different, and our experiences can further shape our personalities.

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Originally Posted by Blaster Master View Post
To take it a step farther, if we take two identical computers programmed with identical learning algorithms and even their random number generators are seeded identically, given different data, what they learn will be somewhat different. Over the course of billions of trials, as we have with humans, there will be sufficient variation that learned behaviors will differ.
Yes, even identical twins who are raised together can turn out quite different. (In tests, 50% are more evil than their sibling).

Quote:
Originally Posted by Blaster Master View Post
I think the more interesting part here is that, by and large, we actually do have a lot of common learned behaviors. For instance, the vast majority of people have roughly similar ideas of a moral code and general ideas of some tendencies intrinsic to their cultures. It's like when we compare someone with a genius level IQ to someone with a very low IQ and we focus on how different their level of intelligence is, but compared to any other species, their relative intelligence is actually pretty darn similar.
Again, from an evolutionary point of view, the subset of possible behaviours that lead to survival is very small. A very important part of our environment is other people. Our ancestors consistantly survived long enough to get it on, as part of a social group. Howling at the moon and attacking anything blue isn't a recipe for success.

Quote:
Originally Posted by Blaster Master View Post
Again, the part I find interesting is that we are in fact so remarkably similar, with well over 99% of our genes being identical. Overall, even our inherited behavior is remarkably similar as social creatures, speech, family structures, etc. and yet we still find the differences we do have and they appear rather larger than they are.
To us, someone who listens to rock seems very different to someone who listens to jazz. But both would have far more in common with a hypothetical person who listened to nails on a blackboard for entertainment. We can be quite different, while still having an awful lot in common.

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Originally Posted by Duckster View Post
Add in the randomness of cell divisions from conception onward and chemical combinations and reactions that go on in your body (and brain) are not the exact same as anyone else.
Yes, DNA is more like a recipe than a blueprint. Hell, in some animals, such as crocodiles, sex can be determined by the temperature the egg incubates at.
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  #15  
Old 02-04-2011, 03:41 PM
Trubie Trubie is offline
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First time poster. This topic has always fascinated me.


The one thing that's always confused me about personalities is that people within the same family can have vastly different personalities. The differences can be so great that these biological families break apart (not uncommon). I've always noticed, that certain personalities can be so different from what's considered a "good" personality that people possessing these negative personalities are shunned from society in most aspects. I don't understand how anyone would evolve into these personalities. You think the genes for personalities that are difficult would die out. While I do think the life one leads can affect one's personality, I've also noticed two people can go through a bad situation and one will come out of it personality intact. Lastly, it never fails to amaze me how many people have a "negative" personality and yet had never had a life, or situation, that would cause such a deviant personality. Due to the comforts human have in this age, I wonder if personality is last key to survival of one's dna. It seems many things in life can be gain and/or altered. However, personality seems to be the one thing a person is stuck with...
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Old 02-04-2011, 03:53 PM
Lemur866 Lemur866 is offline
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Suppose human personalities were all a lot more alike. Say, everyone was less aggressive. Every human on the planet made more alike by the wave of a magic wand. Well, we'd still perceive differences in personality between people.

So unless every human personality were absolutely identical (such that we could barely tell each other apart) there would still be personality differences, right? And then you'd be wondering, on this planet were everyone was a lot more alike, why everyone was so different from each other.

In other words, you notice the differences because they are differences, but you take the similarities for granted. All humans are more like each other than any of them are like chimpanzees, or gorillas. We just don't notice how everyone is the same for the same reason fish don't notice water. The similarities are the background, so only the differences are important.
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  #17  
Old 02-04-2011, 05:48 PM
monstro monstro is online now
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Apart from the genetic argument, from the moment we are conceived, we experience different environments. Even twins sharing the same womb experience different gradients of hormones, nutrition, and comfort during the gestation period. I remember kinda freaking out when my mother informed me that my sister had been sitting on me throughout our time together in utero. This may explain why, as a two-month old, I had an inguinal hernia. It may also explain why my head was always tilted to the side in all my newborn pictures and why I had to wear braces and orthopedic shoes to correct my pigeon toes as a toddler. Maybe it explains why my sis has always been taller than me. Who knows how being the "damaged" twin affected how my family related to me, and how I viewed myself?

So from the very start, even people with identical DNA will have different experiences that could shape their personalities.

As babies, we are also treated differently. Some of us had very engaged, verbal parents who attended to every cry and demand. Some of us had very cold, quiet, detached parents who were from the "let them cry it out" school of parenting. Most of us had parents who fell in between. I have no doubt that having siblings, and your birth position relative to those siblings, also has a role to play in what personality you develop. I'm not one of them, but I have met people who have an uncanny ability of guessing if someone's the youngest or oldest child in their family, just based on their personality traits.

I don't think different personalities have evolved. I think they are just an emergent property of all the levels of our body's organization interacting with the environment. Some personality traits could help increase one's fitness (in a passing-the-genes-on-to-the-next-generation definition of the term). The most socially adept person will most certainly mate with someone, even if they harbor bad personality quirks (like possessing a quick temper). But because personality is not defined solely by genetics, it's hard to say whether or not those traits are adaptive (as in, shaped by evolution) or are simply acquired skills. Seems to me that since we do have a wide variety of personalities to choose from, one could argue that having diverse personalities (or rather, having individuals with the potential to form different personalities) in a population has been advantageous and possibly the result of evolution. "We need all types" is not an empty saying.

Quote:
Originally Posted by sassyfras
Ok, this is basic perhaps, but I was reading about personality tests and personality types (conscientious, dramatic) disorders (borderline), but then i thought: Why do (different) people each have different personalities?

Why don't we all have the same type of personality? Did we evolve this way randomly and it happens to help us because of personality 'diversity'? Then why did we evolve having bad things like borderline personality disorder?
This is like asking "why did we evolve things like diabetes"? Not everything about us is the result of natural selection or serves some great purpose. And personality, as I said before, is an emergent property of many interacting elements. As a system becomes more complex, it becomes more subject to chaos simply because there are so many things that can go wrong. So people can become crazy for the same reason your computer breaks down. Simply said, things fall apart.

But it is interesting that you would mention BP. While it gets talked a lot about here and the sufferers are villifed as evil incarnate, if one actually reads the literature about this disorder, they'll find that people diagnosed with BP, as well as many narcissists, are often pictures of success, at least superficially. They often succeed at their jobs and are very competent at what they do. I wouldn't be surprised if a lot of the folks on Wall Street have some anti-social PD traits as well.

Some folks here know that I have schizoid PD. I would say that it too comes with its gifts (self-sufficiency, creativity and originality, even altruism). However it is true that most schizoids would make baby Darwin cry at our negative level of fitness, and so in that way it can be conceived that we have "bad" personalities. But just like personality, society is an emergent property as well. Perhaps for a society to be "successul", some subset of the population has to be intensely focused on thinking and creating while everyone else is having sex and having babies. It is speculated that many of history's greatest thinkers had quirky--dare I say--disordered personalities.

Perhaps people with "bad" personalities are not broken in an absolute sense. It all hinges on context. I would be absolutely broken if I were forced into marriage and raising children. But let me live my life the way I want to and I'm fine. I can even contribute positively to society, if I want to.

Last edited by monstro; 02-04-2011 at 05:50 PM..
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