1 00:00:00,130 --> 00:00:01,800 The following content is provided 2 00:00:01,800 --> 00:00:04,030 under a Creative Commons license. 3 00:00:04,030 --> 00:00:06,880 Your support will help MIT OpenCourseWare continue 4 00:00:06,880 --> 00:00:10,740 to offer high quality educational resources for free. 5 00:00:10,740 --> 00:00:13,350 To make a donation, or view additional materials 6 00:00:13,350 --> 00:00:17,237 from hundreds of MIT courses, visit MIT OpenCourseWare 7 00:00:17,237 --> 00:00:17,862 at ocw.mit.edu. 8 00:00:21,470 --> 00:00:24,900 PROFESSOR: Did anybody have any questions about this path 9 00:00:24,900 --> 00:00:29,070 analysis, which is where we ended the class last time? 10 00:00:29,070 --> 00:00:37,780 It's a way to find the probability for two individuals 11 00:00:37,780 --> 00:00:42,100 when you know they're related in some way. 12 00:00:42,100 --> 00:00:50,650 But if you have their-- you can draw the family tree, 13 00:00:50,650 --> 00:00:54,510 you're able to then, using path analysis, 14 00:00:54,510 --> 00:01:00,740 you can find the probability that the two alleles at one 15 00:01:00,740 --> 00:01:04,047 locus are identical, or how many of them 16 00:01:04,047 --> 00:01:05,130 are going to be identical. 17 00:01:10,480 --> 00:01:13,420 It's called the inbreeding coefficient, 18 00:01:13,420 --> 00:01:14,815 or the coefficient of kinship. 19 00:01:18,200 --> 00:01:21,820 Both terms are used. 20 00:01:21,820 --> 00:01:26,920 But you can use the same thing to compute just how many genes 21 00:01:26,920 --> 00:01:29,306 do you get from your great grandparent, for example. 22 00:01:39,220 --> 00:01:43,690 So this is the only slide from the first class 23 00:01:43,690 --> 00:01:45,220 I didn't get to. 24 00:01:45,220 --> 00:01:51,220 We were talking about notes from EO Wilson's book. 25 00:01:51,220 --> 00:01:57,340 I read the abridged addition for making those notes. 26 00:01:57,340 --> 00:02:01,500 But he talks about the possibility 27 00:02:01,500 --> 00:02:03,170 of inbreeding taboos. 28 00:02:03,170 --> 00:02:07,240 But when he introduces it he uses some more terms 29 00:02:07,240 --> 00:02:09,729 that are interesting. 30 00:02:09,729 --> 00:02:14,970 He introduces by defining the effective population number. 31 00:02:14,970 --> 00:02:19,410 And that, I've defined it at the bottom there, 32 00:02:19,410 --> 00:02:22,190 the number of individuals in an ideal randomly 33 00:02:22,190 --> 00:02:24,940 breeding population, with one to one 34 00:02:24,940 --> 00:02:29,970 sex ratio, that would have the same rate of heterozygocity 35 00:02:29,970 --> 00:02:34,580 decrease as the total population under consideration. 36 00:02:34,580 --> 00:02:38,626 So that's what makes it the effective population. 37 00:02:41,650 --> 00:02:45,890 It's usually the smallest number you can have and not 38 00:02:45,890 --> 00:02:47,225 have much inbreeding. 39 00:02:50,320 --> 00:02:52,270 At least you would not have anymore inbreeding 40 00:02:52,270 --> 00:02:54,320 than you would if they were bred randomly 41 00:02:54,320 --> 00:02:55,700 in the larger population. 42 00:02:59,350 --> 00:03:01,850 And the numbers aren't really big. 43 00:03:01,850 --> 00:03:05,240 They get as low as 10 in some species. 44 00:03:05,240 --> 00:03:11,050 But they often are closer to 100. 45 00:03:11,050 --> 00:03:14,420 And then he talks about Wright's Island Model. 46 00:03:14,420 --> 00:03:21,450 Now what that is he has a model of a population that's 47 00:03:21,450 --> 00:03:25,870 divided up into smaller groups. 48 00:03:25,870 --> 00:03:32,150 And we know that it's probably, at least very roughly, 49 00:03:32,150 --> 00:03:35,350 many populations are divided that way-- certainly humans 50 00:03:35,350 --> 00:03:37,425 were throughout much of our evolution. 51 00:03:40,280 --> 00:03:42,930 That's why he calls it the island model, 52 00:03:42,930 --> 00:03:45,510 because he's got the population divided 53 00:03:45,510 --> 00:03:52,370 into these different groups that are-- he computed how big would 54 00:03:52,370 --> 00:03:55,940 those groups have to be in order to meet 55 00:03:55,940 --> 00:03:59,620 this effective population number definition. 56 00:03:59,620 --> 00:04:03,410 And then what are the advantages of a population being 57 00:04:03,410 --> 00:04:05,970 divided that way? 58 00:04:05,970 --> 00:04:08,060 And there very clear advantages because when 59 00:04:08,060 --> 00:04:14,820 you have smaller groups the genetic differences that 60 00:04:14,820 --> 00:04:18,570 appear in the different groups will differ. 61 00:04:18,570 --> 00:04:22,280 And so you will have small genetic differences 62 00:04:22,280 --> 00:04:25,560 appearing in these different groups. 63 00:04:25,560 --> 00:04:28,191 And they'll be maintained if they're not interbreeding. 64 00:04:28,191 --> 00:04:29,690 Of course they would share the genes 65 00:04:29,690 --> 00:04:35,920 as soon as they-- mating involved movement 66 00:04:35,920 --> 00:04:38,120 from one group to the other. 67 00:04:38,120 --> 00:04:41,030 But if they're truly isolated that wouldn't be happening. 68 00:04:41,030 --> 00:04:45,020 What would be the advantage to that? 69 00:04:45,020 --> 00:04:47,630 What would be the advantage if a population were 70 00:04:47,630 --> 00:04:49,490 divided that way? 71 00:04:49,490 --> 00:04:54,370 Well think if there were some big change in the environment, 72 00:04:54,370 --> 00:04:59,310 or new predators appeared, affecting all the groups. 73 00:04:59,310 --> 00:05:02,110 Well if there's genetic differences in the groups then 74 00:05:02,110 --> 00:05:04,320 you're going to get better survival in some groups 75 00:05:04,320 --> 00:05:07,060 than in others. 76 00:05:07,060 --> 00:05:15,330 And that's what Wright, what his model was able to show. 77 00:05:15,330 --> 00:05:18,455 And that's one of the consequences of that model. 78 00:05:23,220 --> 00:05:25,880 [? Menia ?] points out these, what 79 00:05:25,880 --> 00:05:28,050 he calls opposed selection tendencies that 80 00:05:28,050 --> 00:05:32,370 affects sociality, two very different effects 81 00:05:32,370 --> 00:05:36,750 in small groups-- that you have a greater chance of inbreeding, 82 00:05:36,750 --> 00:05:42,780 and inbreeding generally lowers individual fitness, 83 00:05:42,780 --> 00:05:46,940 depresses performance, lowers genetic adaptability. 84 00:05:46,940 --> 00:05:51,340 So that is more likely to happen especially 85 00:05:51,340 --> 00:05:54,070 if you're well below that effective population number. 86 00:05:57,450 --> 00:06:00,030 But in the small groups of related individuals 87 00:06:00,030 --> 00:06:02,310 there would be very clear advantages 88 00:06:02,310 --> 00:06:04,930 because of greater amounts of altruistic behavior 89 00:06:04,930 --> 00:06:07,690 in close cooperation and groups. 90 00:06:11,370 --> 00:06:14,580 And then he talks about a somewhat different concept, 91 00:06:14,580 --> 00:06:18,600 assortative mating, also known as homogamy. 92 00:06:18,600 --> 00:06:23,200 And this is the tendency you find in all animal groups, 93 00:06:23,200 --> 00:06:24,300 and certainly in humans. 94 00:06:24,300 --> 00:06:26,260 A tendency to choose a mate that looks 95 00:06:26,260 --> 00:06:28,320 similar to oneself or one's close relatives. 96 00:06:34,250 --> 00:06:35,590 What does that mean? 97 00:06:35,590 --> 00:06:41,920 Well it probably means that the group-- 98 00:06:41,920 --> 00:06:44,880 I was talking to the TA's about my worries 99 00:06:44,880 --> 00:06:48,010 that the second project will go out, too. 100 00:06:48,010 --> 00:06:50,970 It's a small chance it's in the connection, 101 00:06:50,970 --> 00:06:56,260 but I don't-- so far, so good. 102 00:07:04,580 --> 00:07:06,616 If you're going to always choose a mate, 103 00:07:06,616 --> 00:07:08,240 someone that looks similar to yourself, 104 00:07:08,240 --> 00:07:11,200 then the chances of the two shared genes, of course, 105 00:07:11,200 --> 00:07:12,540 might be greater. 106 00:07:12,540 --> 00:07:15,570 But that's only in a relatively small number 107 00:07:15,570 --> 00:07:17,715 of genes that affect the superficial appearance. 108 00:07:23,680 --> 00:07:26,360 That was the end of that class. 109 00:07:33,160 --> 00:07:34,700 Then I asked you to read the chapter 110 00:07:34,700 --> 00:07:38,905 on genes, genetic influences on social behavior. 111 00:07:42,020 --> 00:07:46,530 We want to know the difference between genetic determinants 112 00:07:46,530 --> 00:07:50,910 of behavioral traits, genetic determination, and what 113 00:07:50,910 --> 00:07:56,090 sociobiologists-- what their view concerning 114 00:07:56,090 --> 00:07:57,900 genes and behavior is. 115 00:07:57,900 --> 00:08:05,060 Because you know that they've been accused a lot of basically 116 00:08:05,060 --> 00:08:10,720 saying genes are us, major trends are genetic. 117 00:08:10,720 --> 00:08:12,970 Do the genes determine the development 118 00:08:12,970 --> 00:08:15,600 of specific social behaviors? 119 00:08:15,600 --> 00:08:17,400 First of all, I want you to think back 120 00:08:17,400 --> 00:08:19,920 to our discussion of ethology. 121 00:08:19,920 --> 00:08:24,800 We talked about Connor Lawrence and fixed action patterns. 122 00:08:24,800 --> 00:08:29,480 Because ethology was founded on the basis of the heriditability 123 00:08:29,480 --> 00:08:32,409 of fixed action patterns, and many of them 124 00:08:32,409 --> 00:08:34,099 are, of course, social behavior. 125 00:08:39,059 --> 00:08:43,710 But we also knew that a fixed action pattern's not 126 00:08:43,710 --> 00:08:47,130 totally determined by the genes. 127 00:08:47,130 --> 00:08:50,920 It depends on motivational levels. 128 00:08:50,920 --> 00:08:52,550 And the motivational intensity is 129 00:08:52,550 --> 00:08:56,510 influenced by many environmental variables. 130 00:08:56,510 --> 00:08:58,590 But the underlying action patterns, especially 131 00:08:58,590 --> 00:09:00,930 on the motor side, the fixed motor pattern, 132 00:09:00,930 --> 00:09:02,840 is considered genetic. 133 00:09:02,840 --> 00:09:06,190 And there's plenty of evidence for that. 134 00:09:06,190 --> 00:09:09,330 You can even get mouse populations 135 00:09:09,330 --> 00:09:13,530 that are genetically different that show differences 136 00:09:13,530 --> 00:09:17,340 in details of grooming behavior. 137 00:09:17,340 --> 00:09:22,870 And all the members that have one gene, one genetic variant, 138 00:09:22,870 --> 00:09:24,250 will show one type. 139 00:09:24,250 --> 00:09:27,430 And all of the individuals are almost identical. 140 00:09:27,430 --> 00:09:30,110 And the other groups are a little bit different. 141 00:09:30,110 --> 00:09:33,030 Certainly pretty strong evidence for genetic influences 142 00:09:33,030 --> 00:09:34,720 on that behavior. 143 00:09:34,720 --> 00:09:37,270 That is only social behavior, of course, 144 00:09:37,270 --> 00:09:42,340 if there's grooming of each other in a group. 145 00:09:45,020 --> 00:09:47,780 But I want you, next, to remember that 146 00:09:47,780 --> 00:09:56,160 the nature/nurture problem, the way that controversy is 147 00:09:56,160 --> 00:09:59,900 normally dealt with now, especially in sociobiology, 148 00:09:59,900 --> 00:10:08,530 is to remember that-- where are we here?-- 149 00:10:08,530 --> 00:10:12,220 that both nature and nurture are always involved. 150 00:10:12,220 --> 00:10:15,236 You never have a purely genetic determination. 151 00:10:20,890 --> 00:10:23,640 And the other thing that Alcott points out here 152 00:10:23,640 --> 00:10:26,690 is that the genetic studies most relevant to 153 00:10:26,690 --> 00:10:31,050 sociobiology are not developmental genetics 154 00:10:31,050 --> 00:10:32,745 at all, but population genetics. 155 00:10:35,520 --> 00:10:39,540 They deal most directly with the consequences of population 156 00:10:39,540 --> 00:10:42,095 changes and the frequency of different variants, 157 00:10:42,095 --> 00:10:46,500 or alleles, of given genes, not with the means 158 00:10:46,500 --> 00:10:50,370 by which these alleles shape or influence 159 00:10:50,370 --> 00:10:54,100 the biochemical pathways of developing individuals. 160 00:10:54,100 --> 00:10:57,630 And so a lot of times the criticisms 161 00:10:57,630 --> 00:11:00,390 that sociobiologists are genetic determinists 162 00:11:00,390 --> 00:11:03,510 about social behavior is because they don't distinguish 163 00:11:03,510 --> 00:11:05,990 between ultimate and proximate research in biology. 164 00:11:08,760 --> 00:11:20,890 And he considers that the main problem with these criticisms, 165 00:11:20,890 --> 00:11:25,550 especially the critics that argue in this extreme fashion. 166 00:11:25,550 --> 00:11:28,740 They say sociobiologists are talking 167 00:11:28,740 --> 00:11:31,780 about traits that are hereditary, fixed, inevitable, 168 00:11:31,780 --> 00:11:34,270 unchangeable except by future selection 169 00:11:34,270 --> 00:11:36,020 for hereditary alternatives. 170 00:11:36,020 --> 00:11:40,360 Well we know that that can't be true 171 00:11:40,360 --> 00:11:46,600 because of the nature of what we know 172 00:11:46,600 --> 00:11:48,370 about how genes influence behavior. 173 00:11:53,780 --> 00:11:56,420 But let me ask you about-- just leaving 174 00:11:56,420 --> 00:11:59,780 these slides for a minute-- what about these studies 175 00:11:59,780 --> 00:12:02,150 of the ethology, where they're dealing with, 176 00:12:02,150 --> 00:12:08,540 like the cat mating behavior, for example? 177 00:12:08,540 --> 00:12:12,040 And you can find relationships across species, 178 00:12:12,040 --> 00:12:14,800 and the behavior is almost identical in different groups. 179 00:12:14,800 --> 00:12:16,060 Is that not social behavior? 180 00:12:16,060 --> 00:12:19,030 And isn't it genetically determined? 181 00:12:19,030 --> 00:12:22,730 And I would argue that it certainly is. 182 00:12:22,730 --> 00:12:26,620 But there are many learned aspects as well. 183 00:12:26,620 --> 00:12:29,550 So you will find individual differences in a group, 184 00:12:29,550 --> 00:12:33,080 especially on the stimulus side. 185 00:12:33,080 --> 00:12:34,500 They develop different preferences 186 00:12:34,500 --> 00:12:38,200 and so forth, even when the motor side is fairly fixed. 187 00:12:43,390 --> 00:12:47,520 Then Alcott talks about this review done in 1998. 188 00:12:47,520 --> 00:13:00,710 So that was a long time after the books appeared in 1975. 189 00:13:00,710 --> 00:13:03,190 He called it the study of genetically determined 190 00:13:03,190 --> 00:13:03,860 social behavior. 191 00:13:03,860 --> 00:13:08,000 That was the main theme of the review. 192 00:13:08,000 --> 00:13:11,060 But Wilson actually devotes an entire chapter 193 00:13:11,060 --> 00:13:13,550 in his book to explain that although genes 194 00:13:13,550 --> 00:13:15,670 are essential for the development of behavior, 195 00:13:15,670 --> 00:13:19,630 they don't determine it by themselves. 196 00:13:19,630 --> 00:13:24,170 Of course, I think most people who look at genes in behavior 197 00:13:24,170 --> 00:13:26,450 now would say that that would have to be true. 198 00:13:29,270 --> 00:13:32,730 You can go to an extreme, like Richard Alexander did here. 199 00:13:32,730 --> 00:13:39,030 He just points out that genetic determinism 200 00:13:39,030 --> 00:13:43,180 is a ridiculous argument if you exclude environment completely, 201 00:13:43,180 --> 00:13:44,850 environment outside the DNA. 202 00:13:44,850 --> 00:13:46,790 Because it's always there, and there's always 203 00:13:46,790 --> 00:13:50,120 variables, which of course makes us 204 00:13:50,120 --> 00:13:53,450 wonder why the claim has been so persistent. 205 00:13:53,450 --> 00:13:56,890 So I'll deal with that next. 206 00:13:56,890 --> 00:14:00,600 But this is the way Alcock summarizes it, 207 00:14:00,600 --> 00:14:04,450 basically about, at least the chemical environment of the DNA 208 00:14:04,450 --> 00:14:05,550 is always involved. 209 00:14:05,550 --> 00:14:08,870 And that is [INAUDIBLE]. 210 00:14:08,870 --> 00:14:11,420 But I want to point out that a lot of people 211 00:14:11,420 --> 00:14:17,860 who argue against the influence of genes, 212 00:14:17,860 --> 00:14:19,940 they just feel that environment and learning 213 00:14:19,940 --> 00:14:23,940 are a lot more important, that you can discount 214 00:14:23,940 --> 00:14:26,480 a lot of the genetic factors. 215 00:14:26,480 --> 00:14:29,200 They also get upset by thinking about behavior 216 00:14:29,200 --> 00:14:31,590 in a totally deterministic way. 217 00:14:31,590 --> 00:14:33,980 They basically object to the basic assumption 218 00:14:33,980 --> 00:14:38,170 of a scientist, who's trying to explain 219 00:14:38,170 --> 00:14:41,680 physical causes of the effects of whatever they're 220 00:14:41,680 --> 00:14:44,800 investigating, whether its behavior or anything else. 221 00:14:44,800 --> 00:14:48,945 I mean psychologists can't do their work without assuming 222 00:14:48,945 --> 00:14:54,070 that there's specific effects on behavior, including 223 00:14:54,070 --> 00:14:56,570 genetic effects. 224 00:14:56,570 --> 00:14:59,130 And so there are people like that. 225 00:14:59,130 --> 00:15:02,470 They don't like, in general, the deterministic approach 226 00:15:02,470 --> 00:15:03,880 that scientists take. 227 00:15:03,880 --> 00:15:08,280 So a lot of times the criticisms of those people 228 00:15:08,280 --> 00:15:11,180 is much broader than just talking about sociobiology. 229 00:15:11,180 --> 00:15:14,539 But sociobiology is what triggers their ire 230 00:15:14,539 --> 00:15:15,330 more than anything. 231 00:15:21,840 --> 00:15:26,990 So this is an enduring myth, according to Alcock, 232 00:15:26,990 --> 00:15:29,140 despite the fact that all biologists 233 00:15:29,140 --> 00:15:31,460 know that every trait of every organism 234 00:15:31,460 --> 00:15:33,970 develops through this interaction of genes 235 00:15:33,970 --> 00:15:35,440 and environment. 236 00:15:35,440 --> 00:15:38,350 But I think the myth persists. 237 00:15:38,350 --> 00:15:41,880 They don't like this approach, as I just pointed out, 238 00:15:41,880 --> 00:15:43,510 for much more general reasons that 239 00:15:43,510 --> 00:15:45,350 have to do just with sociobiology. 240 00:15:45,350 --> 00:15:48,870 So this is a convenient straw man to set it up like that. 241 00:15:48,870 --> 00:15:51,970 I think it's the nature of human psychology. 242 00:15:51,970 --> 00:15:55,264 We believe in our ability to change our behavior, 243 00:15:55,264 --> 00:15:56,430 and other people's behavior. 244 00:15:59,999 --> 00:16:03,940 And for many people, the flexibility of human behavior 245 00:16:03,940 --> 00:16:08,260 is mistakenly taken as evidence that cultural factors are 246 00:16:08,260 --> 00:16:10,480 the only real determinants of our actions. 247 00:16:10,480 --> 00:16:13,780 In fact, in some of the meetings where these arguments have come 248 00:16:13,780 --> 00:16:18,500 up, people usually outside of sociobiology, 249 00:16:18,500 --> 00:16:23,520 of course, or behavioral biology, will argue that. 250 00:16:23,520 --> 00:16:26,730 Culture is the only real determinant of human behavior. 251 00:16:29,530 --> 00:16:33,290 And then I also feel that championing free will 252 00:16:33,290 --> 00:16:38,770 and freedom of action is pretty understandably very popular. 253 00:16:38,770 --> 00:16:42,430 In fact, I think humans have evolved 254 00:16:42,430 --> 00:16:44,800 an enthusiasm for freedom of action 255 00:16:44,800 --> 00:16:46,730 and a belief in free will. 256 00:16:46,730 --> 00:16:49,220 So I think we should be thinking like sociobiologists 257 00:16:49,220 --> 00:16:50,850 about that. 258 00:16:50,850 --> 00:16:54,100 Why does everybody feel that? 259 00:16:54,100 --> 00:16:56,870 I mean, yes, there are some intellectuals that take a very 260 00:16:56,870 --> 00:17:00,710 deterministic approach, and say, we think we have free will 261 00:17:00,710 --> 00:17:01,380 but we don't. 262 00:17:01,380 --> 00:17:02,720 And they're being philosophical. 263 00:17:02,720 --> 00:17:06,400 But in their own behavior, do they believe in free will? 264 00:17:06,400 --> 00:17:07,745 You bet. 265 00:17:07,745 --> 00:17:08,920 We all do. 266 00:17:08,920 --> 00:17:10,099 I think it's inherited. 267 00:17:10,099 --> 00:17:12,697 And I think it's adaptive to be that way. 268 00:17:18,760 --> 00:17:23,880 Can a difference in one allele change a behavior? 269 00:17:23,880 --> 00:17:27,859 And here's this interesting figure, 3.1, 270 00:17:27,859 --> 00:17:30,020 to explain how a difference in one 271 00:17:30,020 --> 00:17:33,080 allele-- and he has them represented by capital 272 00:17:33,080 --> 00:17:36,470 and small b-- could result in a behavioral difference 273 00:17:36,470 --> 00:17:38,080 between two adults. 274 00:17:38,080 --> 00:17:39,950 And it's a kind of multiplier effect. 275 00:17:39,950 --> 00:17:41,540 This is the way I've reproduced it. 276 00:17:48,030 --> 00:17:52,090 So you start with the fertilized egg. 277 00:17:52,090 --> 00:17:54,600 And here's one individual. 278 00:17:54,600 --> 00:17:59,780 Notice most of the genes are the same except this gene here. 279 00:17:59,780 --> 00:18:05,760 And this could be big B, little b. 280 00:18:05,760 --> 00:18:07,670 But it's different from this individual, who 281 00:18:07,670 --> 00:18:10,750 has the two recessive genes at the same locus. 282 00:18:10,750 --> 00:18:12,870 So his behavior, if it's going to be affected, 283 00:18:12,870 --> 00:18:17,420 will be any effect of that one allele. 284 00:18:17,420 --> 00:18:20,900 And this person doesn't even have that allele. 285 00:18:20,900 --> 00:18:24,090 So he's got to be affected by the other one. 286 00:18:24,090 --> 00:18:29,730 It's just one gene, so one protein. 287 00:18:29,730 --> 00:18:32,850 And that genetic difference, of course, 288 00:18:32,850 --> 00:18:34,334 will interact with the environment. 289 00:18:34,334 --> 00:18:35,875 And the environment can be different. 290 00:18:38,550 --> 00:18:40,140 So the effects, if the environment's 291 00:18:40,140 --> 00:18:41,990 different for these two individuals, 292 00:18:41,990 --> 00:18:45,410 you're going to get differences that affects the adult. 293 00:18:45,410 --> 00:18:49,880 But then as they develop, of course, and neurons develop, 294 00:18:49,880 --> 00:18:53,200 we know that there are many effects of environment 295 00:18:53,200 --> 00:18:56,620 on that that are independent of these. 296 00:18:56,620 --> 00:19:00,610 But that, in fact, this allele could make a difference 297 00:19:00,610 --> 00:19:02,800 in the way these things happen during development. 298 00:19:02,800 --> 00:19:09,420 So the effect here could be present throughout development 299 00:19:09,420 --> 00:19:13,926 with environments, as long as they're slightly different. 300 00:19:13,926 --> 00:19:15,550 It could lead to pretty big differences 301 00:19:15,550 --> 00:19:17,960 into adults, in spite of that allele. 302 00:19:21,370 --> 00:19:24,530 And yet, the differences developed specifically 303 00:19:24,530 --> 00:19:26,360 because of that one genetic difference. 304 00:19:26,360 --> 00:19:31,120 So that's all that we we're talking about here. 305 00:19:31,120 --> 00:19:35,170 So let's talk exactly how and why the relative frequency 306 00:19:35,170 --> 00:19:38,650 of the two alleles could change over multiple generations. 307 00:19:38,650 --> 00:19:43,100 Let's raise the possibilities from what we know. 308 00:19:43,100 --> 00:19:47,150 And these are the things I can think of. 309 00:19:47,150 --> 00:19:53,900 Why B could increase and the recessive trait could decrease. 310 00:19:53,900 --> 00:19:58,440 First of all, if the recessive trait resulted in death 311 00:19:58,440 --> 00:20:00,350 before the age of reproduction, more 312 00:20:00,350 --> 00:20:04,384 often than the dominant trait. 313 00:20:04,384 --> 00:20:06,050 I'm just going to refer to them that way 314 00:20:06,050 --> 00:20:11,040 because that's a common way of expressing 315 00:20:11,040 --> 00:20:15,180 for one allele, the recessive and dominant allele 316 00:20:15,180 --> 00:20:16,220 affecting that gene. 317 00:20:18,740 --> 00:20:21,670 A second thing could be B could result 318 00:20:21,670 --> 00:20:25,880 in behavioral difference, reduce the probability 319 00:20:25,880 --> 00:20:28,560 of successful reproduction in a particular environment, 320 00:20:28,560 --> 00:20:30,119 but not in all environments. 321 00:20:30,119 --> 00:20:31,910 So at least in that particular environment, 322 00:20:31,910 --> 00:20:35,190 the genes would change in their frequency. 323 00:20:35,190 --> 00:20:38,850 All we need is probability differences. 324 00:20:38,850 --> 00:20:42,100 And if the recessive trait resulted in no change 325 00:20:42,100 --> 00:20:45,590 in probability of reproduction, but it 326 00:20:45,590 --> 00:20:50,300 did reduce parental care, that alone, you see, 327 00:20:50,300 --> 00:20:54,720 would result-- because you would have, statistically anyway, 328 00:20:54,720 --> 00:20:58,280 less survival the offspring. 329 00:20:58,280 --> 00:21:01,190 And that would be enough then to lead 330 00:21:01,190 --> 00:21:03,320 to changes over multiple generations 331 00:21:03,320 --> 00:21:04,910 in the frequency of those two genes. 332 00:21:09,950 --> 00:21:13,430 So let's talk about breeding for behavioral traits. 333 00:21:13,430 --> 00:21:16,325 We know that animals are bred for physical traits. 334 00:21:16,325 --> 00:21:18,495 You know how dogs have been bred to look different. 335 00:21:22,830 --> 00:21:25,090 As we see especially in farm animals, 336 00:21:25,090 --> 00:21:29,450 we've bred beef cattle, so they're meatier. 337 00:21:29,450 --> 00:21:31,540 Well what about behavior? 338 00:21:31,540 --> 00:21:34,180 It's been done in the laboratory for a number 339 00:21:34,180 --> 00:21:37,030 of particular behavioral traits, where you ignore 340 00:21:37,030 --> 00:21:39,470 any physical differences and you only 341 00:21:39,470 --> 00:21:41,860 have a measure of behavior. 342 00:21:41,860 --> 00:21:45,250 For example, how loud crickets sing, 343 00:21:45,250 --> 00:21:47,560 and the ones that sing louder you 344 00:21:47,560 --> 00:21:49,650 can breed those with each other. 345 00:21:49,650 --> 00:21:53,960 The ones that sing less. 346 00:21:53,960 --> 00:21:56,524 And at the beginning, they're probably all singing. 347 00:21:56,524 --> 00:21:58,440 But some of them don't sing as loud as others. 348 00:21:58,440 --> 00:22:01,450 And if you keep breeding, you will eventually 349 00:22:01,450 --> 00:22:06,570 end up with a loud singing group and a pretty silent group. 350 00:22:06,570 --> 00:22:08,540 It's also been done with fruit flies. 351 00:22:08,540 --> 00:22:10,500 This has been the most common. 352 00:22:10,500 --> 00:22:13,440 And probably the most famous experiments with fruit flies 353 00:22:13,440 --> 00:22:15,880 are the production of learning mutants first produced 354 00:22:15,880 --> 00:22:18,230 by Chip Quinn of this department. 355 00:22:18,230 --> 00:22:21,630 Most of that work he did when he was at Princeton. 356 00:22:21,630 --> 00:22:26,350 And he produced strains of fruit flies 357 00:22:26,350 --> 00:22:29,470 that in a particular learning test that he had set up 358 00:22:29,470 --> 00:22:34,530 to screen the fruit flies, they were particularly stupid. 359 00:22:34,530 --> 00:22:36,380 And he named them after vegetables. 360 00:22:36,380 --> 00:22:41,790 So he has rutabaga, he has turnip, and such individuals. 361 00:22:41,790 --> 00:22:43,870 And he became well known for that 362 00:22:43,870 --> 00:22:47,450 work-- the learning mutants in fruit flies. 363 00:22:47,450 --> 00:22:54,300 It's also been done in mice and in rats. 364 00:22:54,300 --> 00:22:57,960 In mice they've produced spatial learning differences 365 00:22:57,960 --> 00:22:59,850 in different groups, and groups that 366 00:22:59,850 --> 00:23:02,160 differ in nest building activity. 367 00:23:02,160 --> 00:23:04,770 You just select the ones that are 368 00:23:04,770 --> 00:23:07,970 most vigorous about building big nests, 369 00:23:07,970 --> 00:23:10,030 and the one's that don't build such big nest, 370 00:23:10,030 --> 00:23:12,210 and don't nest in such a vigorous way. 371 00:23:12,210 --> 00:23:15,430 And if you breed them selectively 372 00:23:15,430 --> 00:23:16,940 for those behavioral traits, you'll 373 00:23:16,940 --> 00:23:21,140 eventually get groups that are very, very different 374 00:23:21,140 --> 00:23:22,760 in the way they build nests. 375 00:23:22,760 --> 00:23:25,320 And you can do the same thing for spatial learning problems. 376 00:23:25,320 --> 00:23:27,810 And there, the best known is the rat experiments, 377 00:23:27,810 --> 00:23:33,900 where they had what's called the Hebb-Williams maze. 378 00:23:33,900 --> 00:23:36,812 A fairly complex maze that they could change easily. 379 00:23:36,812 --> 00:23:38,770 They could change the problems so the rat would 380 00:23:38,770 --> 00:23:40,240 be trained on one, and then they'd 381 00:23:40,240 --> 00:23:44,710 change the barriers around and test them again, and do that 382 00:23:44,710 --> 00:23:45,330 repeatedly. 383 00:23:45,330 --> 00:23:48,110 And they'd come up with a measure of how intelligent-- 384 00:23:48,110 --> 00:23:50,760 it was called a rat intelligence test, 385 00:23:50,760 --> 00:23:52,912 how smart are they in learning mazes. 386 00:23:52,912 --> 00:23:54,870 And of course, some of them learned much better 387 00:23:54,870 --> 00:23:55,960 than others. 388 00:23:55,960 --> 00:23:58,080 And so again, we can selectively breed them 389 00:23:58,080 --> 00:23:59,720 for how well they learn the maze. 390 00:23:59,720 --> 00:24:02,390 We can have the ones to learn better. 391 00:24:02,390 --> 00:24:06,260 We'll interbreed those ones that learn more poorly. 392 00:24:06,260 --> 00:24:09,070 And you end up with a maze bright, maze dull strain. 393 00:24:09,070 --> 00:24:13,430 And then you can test for other differences, 394 00:24:13,430 --> 00:24:15,060 and what else happens to this animal? 395 00:24:15,060 --> 00:24:16,143 What happens in the brain? 396 00:24:19,810 --> 00:24:22,920 It was the fruit fly work that led most directly 397 00:24:22,920 --> 00:24:25,380 to neuroscience studies. 398 00:24:25,380 --> 00:24:27,900 In fact Chip, after he came here, 399 00:24:27,900 --> 00:24:33,020 eventually did zero in on a particular gene 400 00:24:33,020 --> 00:24:37,000 for a particular factor in the brain 401 00:24:37,000 --> 00:24:40,500 that was found by other groups also 402 00:24:40,500 --> 00:24:41,900 to be involved in learning. 403 00:24:45,850 --> 00:24:50,170 And when we deal with humans, the best studies probably 404 00:24:50,170 --> 00:24:54,450 that support genetic influences on behavior, 405 00:24:54,450 --> 00:24:57,210 are the twin studies. 406 00:24:57,210 --> 00:25:03,930 Do you all know the experiments studying concordance rates? 407 00:25:03,930 --> 00:25:05,980 First of all, you have to collect 408 00:25:05,980 --> 00:25:13,270 large numbers of identical twins so that you 409 00:25:13,270 --> 00:25:19,070 can either test them or find out a lot about them. 410 00:25:19,070 --> 00:25:22,550 For example, do they become schizophrenic? 411 00:25:22,550 --> 00:25:25,730 And so that's certainly a big behavioral difference, 412 00:25:25,730 --> 00:25:27,350 the ones that become schizophrenic 413 00:25:27,350 --> 00:25:28,880 and the one's that don't. 414 00:25:28,880 --> 00:25:34,550 So you find out, if one of the twins, you find out, 415 00:25:34,550 --> 00:25:37,980 is schizophrenic, what is the probability that his twin will 416 00:25:37,980 --> 00:25:38,930 have schizophrenia? 417 00:25:38,930 --> 00:25:42,680 Do you know difference what the probability is? 418 00:25:42,680 --> 00:25:45,510 It's about 2/3. 419 00:25:45,510 --> 00:25:48,620 So it's not totally genetic. 420 00:25:48,620 --> 00:25:53,430 And it's interesting that that 2/3 for schizophrenia 421 00:25:53,430 --> 00:25:57,480 also applies to the kind of diabetes I have. 422 00:25:57,480 --> 00:26:01,600 If I had a twin brother-- it would 423 00:26:01,600 --> 00:26:06,180 have to be a brother because it would have to be monozygotic-- 424 00:26:06,180 --> 00:26:08,460 the brother would have a 2/3 chance 425 00:26:08,460 --> 00:26:10,910 of having the same thing. 426 00:26:10,910 --> 00:26:14,660 The concordance rate is not 100%. 427 00:26:14,660 --> 00:26:18,860 So that just means there has to be environmental factors that 428 00:26:18,860 --> 00:26:21,620 also have a strong influence. 429 00:26:21,620 --> 00:26:28,580 And the degree to which the genetics and environment play 430 00:26:28,580 --> 00:26:33,620 roles can be estimated from just studying concordance rates. 431 00:26:33,620 --> 00:26:36,250 And that has been done for a number of different things. 432 00:26:40,890 --> 00:26:45,190 About the selected reading for behavioral traits, 433 00:26:45,190 --> 00:26:49,850 I like many of the examples in this book, by Temple Grandin. 434 00:26:49,850 --> 00:26:51,620 She's a very interesting lady. 435 00:26:51,620 --> 00:26:55,080 She's actually, I believe, come here to give a talk once, 436 00:26:55,080 --> 00:26:56,690 at least I've heard her. 437 00:26:56,690 --> 00:27:03,230 I think when I heard her she was promoting one of her books, 438 00:27:03,230 --> 00:27:06,340 probably this one, at the bookstore 439 00:27:06,340 --> 00:27:09,200 in Porter Square, where they get authors to come every week, 440 00:27:09,200 --> 00:27:13,580 and sometimes twice a week, to give talks on their new books. 441 00:27:13,580 --> 00:27:17,270 And I met her. 442 00:27:17,270 --> 00:27:21,000 I had a copy of her book, she signed it and talked to me 443 00:27:21,000 --> 00:27:23,990 about the teaching I was doing at MIT and so forth. 444 00:27:23,990 --> 00:27:25,690 Gave me permission, carte blanche, 445 00:27:25,690 --> 00:27:28,850 to use anything in her book in the class. 446 00:27:28,850 --> 00:27:34,280 So she points out various things the behavioral traits 447 00:27:34,280 --> 00:27:37,100 that dogs have been bred for. 448 00:27:37,100 --> 00:27:39,870 They've been bred, as you know, for herding ability-- 449 00:27:39,870 --> 00:27:43,350 for example, the sheep dog. 450 00:27:43,350 --> 00:27:46,070 If you want to herd sheep, and you really 451 00:27:46,070 --> 00:27:49,660 do need dogs to do it efficiently, 452 00:27:49,660 --> 00:27:52,690 you don't want to choose just any dog. 453 00:27:52,690 --> 00:27:55,560 No matter how smart he is, how loyal, 454 00:27:55,560 --> 00:27:57,940 they are genetically different. 455 00:27:57,940 --> 00:28:00,990 And they have been bred specifically for herding. 456 00:28:00,990 --> 00:28:05,890 So the sheep dog is very, very good. 457 00:28:05,890 --> 00:28:09,760 You're enhancing certain fixed action patterns 458 00:28:09,760 --> 00:28:13,870 and decreasing the influence of other fixed action patterns. 459 00:28:13,870 --> 00:28:21,730 In a way, you're enhancing detecting and stalking 460 00:28:21,730 --> 00:28:22,850 behavior. 461 00:28:22,850 --> 00:28:24,900 But you're inhibiting the later parts 462 00:28:24,900 --> 00:28:27,740 of the predatory behavior. 463 00:28:27,740 --> 00:28:29,390 They never attack the sheep. 464 00:28:33,550 --> 00:28:35,660 Predatory attack is also determined 465 00:28:35,660 --> 00:28:39,360 by multiple genes, or multiple components. 466 00:28:39,360 --> 00:28:42,030 It's not a single fixed action pattern, really, at least 467 00:28:42,030 --> 00:28:43,860 on the motor side. 468 00:28:43,860 --> 00:28:46,970 Then retrievers, same kind of thing. 469 00:28:46,970 --> 00:28:48,990 Some dogs are terrible retrievers. 470 00:28:48,990 --> 00:28:52,130 But if you get a golden retriever, or a Labrador 471 00:28:52,130 --> 00:28:57,870 retriever, very easy because it's part of their genetics. 472 00:28:57,870 --> 00:29:02,070 And of course their trained for hunting, pointing. 473 00:29:02,070 --> 00:29:04,970 I remember my father, who hunted pheasants, 474 00:29:04,970 --> 00:29:08,330 he had a pointer when I was a little kid. 475 00:29:08,330 --> 00:29:14,320 And I still remember that dog, because he was so incredibly-- 476 00:29:14,320 --> 00:29:16,375 not just so incredibly loyal to my father, 477 00:29:16,375 --> 00:29:22,740 and not to his kids-- he was so good at what he did. 478 00:29:22,740 --> 00:29:26,520 He would stay right at my father's side. 479 00:29:26,520 --> 00:29:30,110 I mean they're used for they're incredibly good senses, 480 00:29:30,110 --> 00:29:38,120 but also for their ability to detect the pheasant, 481 00:29:38,120 --> 00:29:43,860 and then stop and withhold their tendency to try 482 00:29:43,860 --> 00:29:47,020 to grab it and attack it themselves. 483 00:29:47,020 --> 00:29:49,430 Pheasants are mostly on the ground. 484 00:29:49,430 --> 00:29:52,720 They can fly to get away. 485 00:29:52,720 --> 00:29:55,685 So he would become rigid and go into this posture. 486 00:29:55,685 --> 00:29:58,190 It was very obvious. 487 00:29:58,190 --> 00:30:02,645 And then, little signal from my father, then the dog 488 00:30:02,645 --> 00:30:05,050 would rush forward. 489 00:30:05,050 --> 00:30:08,000 Not to try to kill the pheasant, but to flush him 490 00:30:08,000 --> 00:30:10,280 so he would fly up. 491 00:30:10,280 --> 00:30:12,030 Because people that hunt like this 492 00:30:12,030 --> 00:30:15,080 usually wait, if they can't shoot them in air-- 493 00:30:15,080 --> 00:30:17,220 they're not good enough shots for that-- then they 494 00:30:17,220 --> 00:30:22,120 don't succeed in getting the pheasant. 495 00:30:22,120 --> 00:30:23,820 And I remember the situation where 496 00:30:23,820 --> 00:30:26,130 there were two pheasants pulled up. 497 00:30:26,130 --> 00:30:29,500 And my father had a double barreled shotgun. 498 00:30:29,500 --> 00:30:31,580 And he got both pheasants. 499 00:30:31,580 --> 00:30:34,240 And then another little signal, out the dog 500 00:30:34,240 --> 00:30:36,420 went to retrieve them. 501 00:30:36,420 --> 00:30:38,010 So he could do both of these things, 502 00:30:38,010 --> 00:30:42,520 retrieving, pointing, hunting. 503 00:30:42,520 --> 00:30:46,060 And yet many, many breeds of animals, you cannot train them. 504 00:30:46,060 --> 00:30:48,750 In fact, they weren't very good with children. 505 00:30:48,750 --> 00:30:53,540 So as his kids started growing older 506 00:30:53,540 --> 00:30:59,530 he gave the pointer to a farmer who had a lot of space. 507 00:30:59,530 --> 00:31:02,862 We were now living in a town. 508 00:31:02,862 --> 00:31:05,320 When he did that hunting we were still outside of the town. 509 00:31:05,320 --> 00:31:08,950 But then he moved into the town so his kids could go to school, 510 00:31:08,950 --> 00:31:15,280 and got a dachshund, much better family dog. 511 00:31:17,930 --> 00:31:20,570 So that's the dog I became most familiar with as I 512 00:31:20,570 --> 00:31:21,920 was growing up. 513 00:31:21,920 --> 00:31:25,700 Farm animals we know have been bred very specifically not just 514 00:31:25,700 --> 00:31:29,560 for their physical nature, but you 515 00:31:29,560 --> 00:31:33,450 can't help but when you're breeding farm animals, 516 00:31:33,450 --> 00:31:38,020 you'll tend to choose the ones that aren't as aggressive. 517 00:31:38,020 --> 00:31:42,285 So aggression has been reduced in the cattle, for example. 518 00:31:45,250 --> 00:31:49,050 And the amount of meat they produce has been increased. 519 00:31:49,050 --> 00:31:52,600 For chickens, of course, it's egg laying ability. 520 00:31:52,600 --> 00:31:53,690 And that's been enhanced. 521 00:31:56,790 --> 00:32:00,280 They also breed chickens, of course, for meat. 522 00:32:00,280 --> 00:32:01,640 Bulls it's a little different. 523 00:32:01,640 --> 00:32:06,230 And you find bulls that are breeders at cattle firms in he 524 00:32:06,230 --> 00:32:08,540 US, where they breed cattle. 525 00:32:08,540 --> 00:32:12,060 Again, they choose bulls they have to limit their aggression. 526 00:32:12,060 --> 00:32:15,854 But you want big, meaty bulls because that's 527 00:32:15,854 --> 00:32:17,020 what you're trying to breed. 528 00:32:22,140 --> 00:32:24,680 My grandfather knew all about this kind 529 00:32:24,680 --> 00:32:26,650 of breeding of the bulls because I 530 00:32:26,650 --> 00:32:30,680 remember he wanted to let us see how he did it. 531 00:32:30,680 --> 00:32:33,852 And he went in on horseback and got a bull. 532 00:32:33,852 --> 00:32:35,310 And here comes the bull and we were 533 00:32:35,310 --> 00:32:36,930 all right there in the yard. 534 00:32:36,930 --> 00:32:40,040 Here comes this charging bull. 535 00:32:40,040 --> 00:32:43,330 You could imagine what we felt. 536 00:32:43,330 --> 00:32:45,180 Here's this charging bull. 537 00:32:45,180 --> 00:32:48,580 But the bull, well known to my grandfather, 538 00:32:48,580 --> 00:32:52,200 was not interested in kids at all. 539 00:32:52,200 --> 00:32:53,900 He was only interested in one thing, 540 00:32:53,900 --> 00:32:56,230 those females in the yard. 541 00:32:56,230 --> 00:32:59,112 So my cousin opened the gate, the bull 542 00:32:59,112 --> 00:33:02,050 ran through and immediately began 543 00:33:02,050 --> 00:33:06,110 soliciting the attentions of the females. 544 00:33:06,110 --> 00:33:08,820 But of course, if you're using the bulls for other things, 545 00:33:08,820 --> 00:33:11,810 like bullfighting, then you breed them differently. 546 00:33:11,810 --> 00:33:15,530 And there are bull breeders in Spain 547 00:33:15,530 --> 00:33:21,130 that specifically breed bulls for their ferocity in bull 548 00:33:21,130 --> 00:33:22,930 fighting. 549 00:33:22,930 --> 00:33:24,740 And we know, of course, we're more 550 00:33:24,740 --> 00:33:26,550 familiar with breeding of horses. 551 00:33:26,550 --> 00:33:30,300 And they've been bred for various things, for speed-- 552 00:33:30,300 --> 00:33:38,880 the Thoroughbred-- for herding cattle-- the quarter horse. 553 00:33:38,880 --> 00:33:41,130 They're actually faster than Thoroughbred 554 00:33:41,130 --> 00:33:43,270 for a quarter of a mile. 555 00:33:43,270 --> 00:33:45,940 But they can't keep up with the Thoroughbred in a longer race. 556 00:33:49,740 --> 00:33:51,590 So there are several breeds of horses. 557 00:33:51,590 --> 00:33:56,490 We know that workhorses tend to be bigger, meatier, stronger, 558 00:33:56,490 --> 00:33:57,710 but slower. 559 00:33:57,710 --> 00:34:00,560 But they're used to pull things-- pull wagons, 560 00:34:00,560 --> 00:34:03,150 pull plows, and so forth. 561 00:34:03,150 --> 00:34:06,660 Fewer of them now, but so some of them are still maintained. 562 00:34:06,660 --> 00:34:10,949 So very specific breeding for behavioral traits. 563 00:34:10,949 --> 00:34:14,320 So this question concerns the problems 564 00:34:14,320 --> 00:34:16,510 that often happen when animals are 565 00:34:16,510 --> 00:34:19,110 bred for a single physical trait. 566 00:34:19,110 --> 00:34:21,929 What happens to them? 567 00:34:21,929 --> 00:34:24,449 It's common for behavioral problems to appear. 568 00:34:24,449 --> 00:34:29,280 And this is discussed quite a bit in Temple Grandin's book. 569 00:34:29,280 --> 00:34:32,370 Her example I like was collie dogs, 570 00:34:32,370 --> 00:34:39,107 because when I was growing up I remember Lassie. 571 00:34:39,107 --> 00:34:40,940 I don't know if you even know who Lassie is, 572 00:34:40,940 --> 00:34:43,480 but that was a popular dog in Hollywood movies. 573 00:34:47,130 --> 00:34:52,469 Lassie grew up before this intense breeding 574 00:34:52,469 --> 00:34:56,719 in this period started to change the appearance of collies 575 00:34:56,719 --> 00:35:00,415 to make them have narrower an narrower skulls 576 00:35:00,415 --> 00:35:03,920 and emphasized the needle nose. 577 00:35:03,920 --> 00:35:08,300 So she said the result was brainless ice picks. 578 00:35:08,300 --> 00:35:09,715 Not like Lassie at all. 579 00:35:12,220 --> 00:35:16,570 And that's the danger if you just ignore behavior 580 00:35:16,570 --> 00:35:20,270 when you're breeding for a particular physical trait. 581 00:35:20,270 --> 00:35:22,410 And this is not the only example. 582 00:35:22,410 --> 00:35:25,740 Breeds of dogs have particular problems. 583 00:35:25,740 --> 00:35:27,930 Usually it's that they get certain diseases. 584 00:35:27,930 --> 00:35:31,130 Or Cocker Spaniels, for example, many of them 585 00:35:31,130 --> 00:35:33,410 get a type of epilepsy. 586 00:35:33,410 --> 00:35:36,250 That's certainly a major behavioral problem, 587 00:35:36,250 --> 00:35:38,890 behavioral disease they get because 588 00:35:38,890 --> 00:35:40,510 of this breeding for their appearance. 589 00:35:44,300 --> 00:35:48,230 So is it true that no genes for human behavior have been found? 590 00:35:51,170 --> 00:35:53,360 The argument was that we can dispense 591 00:35:53,360 --> 00:35:55,450 with the direct evidence for a genetic basis 592 00:35:55,450 --> 00:36:00,780 of human social forms in a single word, no evidence. 593 00:36:00,780 --> 00:36:04,300 And here's another quote from this book, called 594 00:36:04,300 --> 00:36:09,480 Not In Our Genes, by a Harvard professor, Lewonton, Rose, 595 00:36:09,480 --> 00:36:11,580 a British professor, and Kamin, I 596 00:36:11,580 --> 00:36:14,141 don't remember where he's from. 597 00:36:14,141 --> 00:36:17,150 He said , no one has ever been able to relate any aspect 598 00:36:17,150 --> 00:36:20,070 of human social behavior to any particular gene or set 599 00:36:20,070 --> 00:36:20,610 of genes. 600 00:36:20,610 --> 00:36:22,700 Is that true still? 601 00:36:22,700 --> 00:36:24,770 I don't think so. 602 00:36:24,770 --> 00:36:28,280 First of all, in your book there, Alcock just points 603 00:36:28,280 --> 00:36:30,730 out the absence of evidence isn't really 604 00:36:30,730 --> 00:36:32,890 evidence of absent, of non involvement 605 00:36:32,890 --> 00:36:34,245 of genes in social development. 606 00:36:36,880 --> 00:36:39,160 I guess it seemed to him that way, 607 00:36:39,160 --> 00:36:40,890 and that was the argument he made. 608 00:36:40,890 --> 00:36:43,060 But I would point out more recent evidence 609 00:36:43,060 --> 00:36:51,310 for specific genes we say for a social behavior. 610 00:36:51,310 --> 00:36:54,310 I want you to keep in mind that even though specific genes are 611 00:36:54,310 --> 00:36:58,870 being found, that are correlated with various social behaviors 612 00:36:58,870 --> 00:37:03,010 and especially behavioral problems, 613 00:37:03,010 --> 00:37:06,030 genes code for proteins. 614 00:37:06,030 --> 00:37:08,110 And if we look at these behaviors, 615 00:37:08,110 --> 00:37:11,400 these abnormalities in humans-- autism, schizophrenia, 616 00:37:11,400 --> 00:37:14,860 and other mental diseases, attention deficit hyperactivity 617 00:37:14,860 --> 00:37:18,160 disorder-- yes, there's genetic contribution to all of these. 618 00:37:18,160 --> 00:37:21,120 There's always multiple genes involved. 619 00:37:21,120 --> 00:37:22,940 Environmental effects are still strong. 620 00:37:27,600 --> 00:37:29,940 So how could a gene that has what 621 00:37:29,940 --> 00:37:32,750 appears to be maladaptive consequences 622 00:37:32,750 --> 00:37:35,220 be present in some animals or people today? 623 00:37:35,220 --> 00:37:38,210 Why wasn't it lost? 624 00:37:38,210 --> 00:37:39,640 It's about the first thing I asked 625 00:37:39,640 --> 00:37:42,980 when I got diabetes is age 24. 626 00:37:42,980 --> 00:37:45,350 What's this gene doing around? 627 00:37:45,350 --> 00:37:49,970 Shouldn't it have disappeared 1,000 years ago? 628 00:37:49,970 --> 00:37:52,170 First of all, it could be a recent mutation 629 00:37:52,170 --> 00:37:54,580 and will be lost. 630 00:37:54,580 --> 00:37:59,790 Or maybe it has its bad effects after reproduction. 631 00:37:59,790 --> 00:38:08,590 I said I got it at age 24, during the age of reproduction. 632 00:38:08,590 --> 00:38:11,410 Many effects do occur later. 633 00:38:11,410 --> 00:38:14,080 It may have affects only in certain environments. 634 00:38:14,080 --> 00:38:16,300 If I were in an environment I wasn't exposed 635 00:38:16,300 --> 00:38:18,760 to the same viruses, I may never gotten it. 636 00:38:18,760 --> 00:38:23,700 It's an autoimmune disease triggered by viruses. 637 00:38:23,700 --> 00:38:26,220 It's also of course because of modern medical treatments. 638 00:38:26,220 --> 00:38:29,150 But it's also-- remember genetic swamping. 639 00:38:29,150 --> 00:38:31,970 If you've forgotten what that is, go back and read it. 640 00:38:31,970 --> 00:38:36,400 It was in my notes, and you could find it also on the web. 641 00:38:36,400 --> 00:38:39,710 And then I'm posting these homework questions. 642 00:38:39,710 --> 00:38:42,030 It's already at the end of the class here. 643 00:38:42,030 --> 00:38:44,280 But I am willing to give you-- I want 644 00:38:44,280 --> 00:38:47,940 you to spend most of the time on this one. 645 00:38:47,940 --> 00:38:49,440 The others should be easier for you. 646 00:38:49,440 --> 00:38:52,190 If you have trouble with those, I'm happy to give you hints. 647 00:38:52,190 --> 00:38:53,632 I'm asking you to do these. 648 00:38:53,632 --> 00:38:56,090 They're similar to homework I gave last year because I want 649 00:38:56,090 --> 00:38:57,673 you to think about these things and be 650 00:38:57,673 --> 00:39:02,020 clear about the type of thinking you need to do. 651 00:39:02,020 --> 00:39:04,400 And this is the one that causes the most controversy. 652 00:39:04,400 --> 00:39:05,830 So think about that. 653 00:39:05,830 --> 00:39:09,240 And you can ask me about it on Friday, if you wish. 654 00:39:09,240 --> 00:39:11,970 And I'm happy to give you some suggestions.