1 00:00:00,009 --> 00:00:04,599 The debate between nature and nurture is almost as old as the chicken versus the egg. 2 00:00:04,610 --> 00:00:06,409 What is more likely to influence how we 3 00:00:06,420 --> 00:00:09,319 actually develop a personality and how we behave? 4 00:00:09,329 --> 00:00:13,079 Is it the genes that we're born with? or, Are we taught and molded by our parents, 5 00:00:13,090 --> 00:00:14,500 our school teachers, and our culture? 6 00:00:14,510 --> 00:00:18,190 Behaviorist and humanist perspectives take on the nurture side of the debate. 7 00:00:18,200 --> 00:00:20,049 They believe that you can become anyone you want 8 00:00:20,059 --> 00:00:22,270 to with the right environment and the right stimuli. 9 00:00:22,280 --> 00:00:24,170 But let's talk about the nature side, 10 00:00:24,180 --> 00:00:28,180 the biological perspective of personality gives us more questions and answers 11 00:00:28,190 --> 00:00:30,856 to think about as we reflect on our own personalities. 12 00:00:30,865 --> 00:00:34,576 So, first off, I need to talk about something called evolutionary psychology. 13 00:00:34,585 --> 00:00:38,116 Some of the earliest and most famous examples of the biological 14 00:00:38,125 --> 00:00:41,465 perspective is ideas that were brought forth by Charles Darwin. 15 00:00:41,476 --> 00:00:44,256 Darwin was the father of evolutionary psychology. 16 00:00:44,265 --> 00:00:48,796 Now, his theories of evolution suggested that species evolve over time, 17 00:00:48,805 --> 00:00:52,986 small adaptations happen throughout time that turn into species evolving. 18 00:00:52,995 --> 00:00:55,995 He said that members of the same species with stronger traits were 19 00:00:56,006 --> 00:00:59,236 more likely to reproduce and pass those traits onto the offspring. 20 00:00:59,245 --> 00:00:59,476 Now, 21 00:00:59,486 --> 00:01:02,111 evolution doesn't just favor physical traits like taller 22 00:01:02,122 --> 00:01:04,092 people or people who are faster at swimming. 23 00:01:04,101 --> 00:01:07,132 This theory actually suggests that our personality comes from 24 00:01:07,141 --> 00:01:09,132 an environment that favored certain traits over time. 25 00:01:09,141 --> 00:01:11,132 For example, in places where it's really hot, 26 00:01:11,141 --> 00:01:13,501 people have more melanin in places where it's really cold, 27 00:01:13,512 --> 00:01:14,991 people usually have less melanin. 28 00:01:15,001 --> 00:01:17,611 Now, if the environment can change our physical biology, 29 00:01:17,622 --> 00:01:21,772 who's to say that it can't change our cognitive biology and our personality? 30 00:01:21,781 --> 00:01:24,162 So let's talk a little bit about the genes and the brain. 31 00:01:24,171 --> 00:01:26,582 So where do biologists find our traits? 32 00:01:26,592 --> 00:01:29,872 Well, they would say they find them in our genes and our genetics in our brain. 33 00:01:29,938 --> 00:01:33,447 To test this theory, psychologists have studied identical twins. 34 00:01:33,458 --> 00:01:37,708 Now, identical twins always have the same genes, the same genetic makeup, 35 00:01:37,718 --> 00:01:41,708 but those who are separated at birth will be grown in two different environments. 36 00:01:41,718 --> 00:01:44,307 So when scientists look at their similarities and differences, 37 00:01:44,318 --> 00:01:46,297 they can get a really good idea on what is 38 00:01:46,307 --> 00:01:49,587 actually nature and what is actually nurture from the environment. 39 00:01:49,597 --> 00:01:51,568 So using these identical twin studies, 40 00:01:51,578 --> 00:01:53,227 we can actually start to narrow down what 41 00:01:53,237 --> 00:01:55,648 percentage of traits may be due to genetics. 42 00:01:55,657 --> 00:01:58,708 If a trait can be passed down through a gene, we call it heritable. 43 00:01:58,718 --> 00:01:59,847 You might have heard this word before. 44 00:01:59,914 --> 00:02:02,573 Heritability is a variance between multiple people that 45 00:02:02,583 --> 00:02:04,704 can be accounted for by genetic differences. 46 00:02:04,713 --> 00:02:08,083 Now, basically that is a lot of words to say that with research, 47 00:02:08,092 --> 00:02:10,622 we can tell how much of someone's behavior is really from 48 00:02:10,633 --> 00:02:13,333 their genes and how much of it is from their environment. 49 00:02:13,343 --> 00:02:16,464 In short, we can tell if something is nature or nurture. 50 00:02:16,473 --> 00:02:16,623 Now, 51 00:02:16,634 --> 00:02:18,983 some of our personality traits are influenced by 52 00:02:18,994 --> 00:02:20,804 genes and some of them are actually not. 53 00:02:20,813 --> 00:02:24,203 For example, according to the identical twin personality research, 54 00:02:24,214 --> 00:02:27,533 some of these traits have been correlated to be influenced by genetics. 55 00:02:27,544 --> 00:02:29,824 For example, social closeness is only 15 56 00:02:30,039 --> 00:02:31,320 percent due to your genetics. 57 00:02:31,330 --> 00:02:32,800 So a lot more of it has to do with the 58 00:02:32,809 --> 00:02:36,559 environment that you were raised in. Achievement orientation is 38%. 59 00:02:36,570 --> 00:02:40,460 Traditionalism is 59% which means it's about half and half nature and 60 00:02:40,470 --> 00:02:45,100 nurture and imagination being 74% is mostly due to your genes. 61 00:02:45,110 --> 00:02:49,720 One example of a gene that can influence a trait is the dopamine four receptor gene. 62 00:02:49,729 --> 00:02:49,779 Now, 63 00:02:49,789 --> 00:02:51,720 this gene has actually been connected with the trait 64 00:02:51,729 --> 00:02:54,899 of thrill seeking and people enjoying something called novelty. 65 00:02:54,910 --> 00:02:58,460 Now, novelty basically means new and fun and exciting ideas. 66 00:02:58,470 --> 00:03:02,376 So there's a perfect example that a gene can actually cause a personality trait. 67 00:03:02,386 --> 00:03:04,255 Although even though that term isn't right, 68 00:03:04,266 --> 00:03:07,835 we don't say that they caused a trait and I'll explain that in the rest of this video. 69 00:03:07,845 --> 00:03:12,636 Take the Jim twins as a real life example, that traits can be passed via genes. 70 00:03:12,645 --> 00:03:16,335 Jim Lewis and Jim Springer were identical twins at birth. 71 00:03:16,345 --> 00:03:19,136 They were separated though. They finally connected at the age of 72 00:03:19,145 --> 00:03:22,755 39 and they quickly made headlines for their very similar lives. 73 00:03:22,766 --> 00:03:23,876 This is actually kind of weird. 74 00:03:23,886 --> 00:03:25,136 Both were the same height, 75 00:03:25,145 --> 00:03:28,016 basically the same weight and they had very similar habits. 76 00:03:28,026 --> 00:03:29,735 What's even weirder is that both of these twins 77 00:03:30,022 --> 00:03:34,841 had both been married twice, and the women that they married had the same first names; 78 00:03:34,852 --> 00:03:38,151 their first wife's name was Linda, and the second wife's name was Betty. 79 00:03:38,162 --> 00:03:39,811 Now, they also drove the same car. 80 00:03:39,822 --> 00:03:43,472 Now you might be wondering how crazy are these similarities? It's unpredictable. 81 00:03:43,481 --> 00:03:46,361 Well, not everything about the Jim twins was similar, 82 00:03:46,371 --> 00:03:49,171 they wore different hairstyles and they chose different professions. 83 00:03:49,182 --> 00:03:52,472 But the story of the Jim twins and other studies of identical twins 84 00:03:52,481 --> 00:03:56,501 show that our genes may be very closely correlated with our personality traits 85 00:03:56,511 --> 00:03:59,908 and the decisions that we make. Other studies show just how important our 86 00:03:59,917 --> 00:04:04,268 brain chemistry is to our reactions and how we actually assess our environment. 87 00:04:04,277 --> 00:04:07,787 Different parts of the brain, so called, go off whenever we make decisions. 88 00:04:07,798 --> 00:04:09,667 So the stronger that these responses are, 89 00:04:09,677 --> 00:04:12,188 the more likely a person is to hold certain personality traits. 90 00:04:12,197 --> 00:04:14,628 For example, as I'll talk about in future videos, 91 00:04:14,638 --> 00:04:19,088 people who are highly neurotic also have stronger responses and their amygdala, 92 00:04:19,096 --> 00:04:22,108 the part of the brain that is responsible for reacting to fear. 93 00:04:22,118 --> 00:04:24,167 So, biological theorists of personality, 94 00:04:24,178 --> 00:04:27,738 they believe that by changing the size of your amygdala, theoretically, 95 00:04:27,747 --> 00:04:30,204 we could change how neurotic you are—that, is if you 96 00:04:30,213 --> 00:04:33,164 can actually control the size of a particular brain section. 97 00:04:33,174 --> 00:04:36,764 Now, the physical structure of the brain may also be linked to personality traits. 98 00:04:36,773 --> 00:04:40,354 Studies from Cambridge University revealed a positive correlation between 99 00:04:40,364 --> 00:04:43,484 openness and more folding in the prefrontal cortices. 100 00:04:43,493 --> 00:04:46,604 So next, I'd like to talk about changes in brain chemistry. 101 00:04:46,614 --> 00:04:47,764 So as we move on, 102 00:04:47,773 --> 00:04:51,884 it is really easy to write off the nature theory as something that you cannot change. 103 00:04:51,894 --> 00:04:54,884 Many people believe that if you're born with an aggressive temperament, 104 00:04:54,894 --> 00:04:56,514 you really can't do much to change your 105 00:04:56,523 --> 00:04:58,884 genes and your tendencies to actually be aggressive. 106 00:04:58,894 --> 00:05:00,700 However, that's not, not exactly true. 107 00:05:00,709 --> 00:05:02,820 Our brains have the potential to change 108 00:05:02,829 --> 00:05:04,720 and actually cause our personality to change. 109 00:05:04,730 --> 00:05:08,679 One famous example of this is the case of that of Phineas Gauge. 110 00:05:08,690 --> 00:05:11,700 Phineas Gauge was a railroad worker in the eighteen forties. 111 00:05:11,709 --> 00:05:14,859 Well, while working, he actually suffered a serious accident, 112 00:05:14,869 --> 00:05:17,899 an explosion sent a tamping iron straight into his head 113 00:05:17,910 --> 00:05:20,070 and it damaged a very large part of his brain. 114 00:05:20,079 --> 00:05:22,839 He actually, I think should have been dead, but he survived. 115 00:05:22,850 --> 00:05:26,959 He somehow survived the horrific accident but not without consequences. 116 00:05:26,970 --> 00:05:29,579 They sent him to the hospital and got him fixed up. When Gauge 117 00:05:29,746 --> 00:05:31,675 came back to work after his accident... 118 00:05:31,686 --> 00:05:32,596 I don't know about you, 119 00:05:32,605 --> 00:05:34,876 but I would not go back to work if something like that happened to me. 120 00:05:34,885 --> 00:05:38,485 Well, anyways, his co-workers noticed some serious changes in his personality. 121 00:05:38,496 --> 00:05:42,045 He wasn't as friendly and he was more prone to using profane language. 122 00:05:42,055 --> 00:05:43,756 He was a changed man. 123 00:05:43,765 --> 00:05:45,436 And his case is a prime example of 124 00:05:45,446 --> 00:05:48,415 how a brain injury can severely affect personality, 125 00:05:48,425 --> 00:05:51,205 which is great evidence for the biological model. 126 00:05:51,216 --> 00:05:53,515 So other things like drugs, poor physical health, 127 00:05:53,526 --> 00:05:56,425 and even smartphones have the ability to actually change 128 00:05:56,436 --> 00:06:00,571 our brain chemistry and thus potentially affect our personality. 129 00:06:00,582 --> 00:06:03,212 So due to the principle of neuroplasticity, 130 00:06:03,221 --> 00:06:05,911 which means that we can essentially rewire our brain, 131 00:06:05,921 --> 00:06:07,411 we can also come to the conclusion that 132 00:06:07,421 --> 00:06:10,141 we can change our brain chemistry and ultimately, 133 00:06:10,152 --> 00:06:11,552 we can change our personality. 134 00:06:11,562 --> 00:06:12,791 So as I wrap this video up, 135 00:06:12,802 --> 00:06:14,131 I'd like to offer a little bit more of 136 00:06:14,141 --> 00:06:16,432 my thoughts on the nature versus nurture debate. 137 00:06:16,441 --> 00:06:20,111 Lessons from the biological perspective of personality and behaviorism, 138 00:06:20,122 --> 00:06:24,221 both offer convincing arguments that nature or nurture influence personality. 139 00:06:24,231 --> 00:06:26,011 So, which side is the winner? 140 00:06:26,022 --> 00:06:30,328 Now, I personally believe that nature and nurture are like ingredients in a cake. 141 00:06:30,338 --> 00:06:32,388 You see to make a cake, you need flour, 142 00:06:32,398 --> 00:06:34,338 you need eggs, and baking soda, and maybe a 143 00:06:34,347 --> 00:06:36,667 few other ingredients to actually make a cake. 144 00:06:36,678 --> 00:06:39,507 But do we say that flour causes a cake? 145 00:06:39,518 --> 00:06:43,238 Not really, we need a little bit of both flour and eggs and those other ingredients. 146 00:06:43,247 --> 00:06:45,638 And only after we make a whole bunch of cakes, 147 00:06:45,648 --> 00:06:47,467 can we actually start to see what happens 148 00:06:47,477 --> 00:06:49,708 when we add or subtract different ingredients? 149 00:06:49,717 --> 00:06:54,227 So flour doesn't cause a cake. Genes don't cause personality. 150 00:06:54,238 --> 00:06:57,167 However, each part is an important section of the whole. 151 00:06:57,178 --> 00:06:59,428 We can connect certain tendencies to act 152 00:06:59,674 --> 00:07:01,373 certain way to different parts of the brain. 153 00:07:01,384 --> 00:07:04,683 When Phineas Gauge's personality changed literally overnight, 154 00:07:04,694 --> 00:07:05,364 for example, 155 00:07:05,373 --> 00:07:07,343 psychologists could pinpoint what parts of his 156 00:07:07,354 --> 00:07:10,003 missing brain had influenced certain traits. 157 00:07:10,014 --> 00:07:10,563 However, 158 00:07:10,574 --> 00:07:12,743 other personality traits are influenced greater 159 00:07:12,753 --> 00:07:14,764 by our environment and our culture. 160 00:07:14,773 --> 00:07:17,044 So if we're taught to value agreeableness and we grew 161 00:07:17,053 --> 00:07:19,644 up in an environment where being agreeable is easily, 162 00:07:19,653 --> 00:07:23,084 we're probably going to be more likely to find ways to be agreeable. 163 00:07:23,093 --> 00:07:27,424 So our personality is influenced by nature or nurture. I personally say both. 164 00:07:27,433 --> 00:07:28,753 If you guys enjoyed this video, 165 00:07:28,764 --> 00:07:31,350 feel free to watch some of other videos in the personality series. 166 00:07:31,359 --> 00:07:32,700 I've worked really hard on them. 167 00:07:32,709 --> 00:07:34,929 Now, if you want to learn more about your own personality, 168 00:07:34,940 --> 00:07:36,269 you can go ahead and check out my free 169 00:07:36,279 --> 00:07:38,640 three in one personality quiz in the description below. 170 00:07:38,649 --> 00:07:40,850 I actually hired a web developer to create it. 171 00:07:40,859 --> 00:07:44,119 It combines three of the major personality quizzes into one 172 00:07:44,130 --> 00:07:46,059 test that you can take in under 10 minutes. 173 00:07:46,070 --> 00:07:47,609 And I've also done some research and I'm going 174 00:07:47,619 --> 00:07:48,910 to try to predict some things about you, 175 00:07:48,920 --> 00:07:52,890 like your political stances, your relationship style, and even your health. 176 00:07:52,899 --> 00:07:54,980 So you can go ahead and check that out in the description below. 177 00:07:54,989 --> 00:07:58,619 I hope you guys enjoy this video and most of all, I hope you learned something. 178 00:07:58,630 --> 00:07:59,540 Thank you for watching.