1 00:00:00,120 --> 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 00:00:22,900 --> 00:00:29,530 PROFESSOR: I decided that we won't have a quiz today. 9 00:00:29,530 --> 00:00:33,825 There will be one more quiz in the class. 10 00:00:38,230 --> 00:00:41,840 It will cover discoveries of sociobiology, which we've 11 00:00:41,840 --> 00:00:43,410 been talking about, and we'll still 12 00:00:43,410 --> 00:00:44,825 talk about today and Friday. 13 00:00:47,740 --> 00:00:50,710 And then we're also going to finish going over 14 00:00:50,710 --> 00:00:56,430 some of the notes I've made on EO Wilson's book Sociobiology. 15 00:00:56,430 --> 00:01:00,830 And I'll try to do that in class next time. 16 00:01:00,830 --> 00:01:04,030 Then we'll have that quiz. 17 00:01:04,030 --> 00:01:05,650 Could easily have been two quizzes. 18 00:01:05,650 --> 00:01:12,380 But instead we'll have one more homework, 19 00:01:12,380 --> 00:01:14,990 and that homework will be for you 20 00:01:14,990 --> 00:01:19,150 to find topics for your reports. 21 00:01:19,150 --> 00:01:20,745 And I'm going to ask for at least two. 22 00:01:24,660 --> 00:01:27,090 You could decide later that you didn't really 23 00:01:27,090 --> 00:01:28,560 like those two well enough, but I 24 00:01:28,560 --> 00:01:32,120 want you to describe two topics. 25 00:01:32,120 --> 00:01:36,060 I'll decide just how long a description we want. 26 00:01:36,060 --> 00:01:38,900 But it means I want you to be searching. 27 00:01:38,900 --> 00:01:41,710 But to do that, you've got to read that assignment. 28 00:01:44,420 --> 00:01:48,870 It's posted near the syllabus up there. 29 00:01:54,600 --> 00:01:57,930 So you will find that online there, near at the beginning 30 00:01:57,930 --> 00:02:02,870 of the Stellar site. 31 00:02:02,870 --> 00:02:05,530 I'm much more specific this year about the way 32 00:02:05,530 --> 00:02:07,170 I want you to do these reports. 33 00:02:07,170 --> 00:02:12,790 So study that in preparation for looking for topics. 34 00:02:12,790 --> 00:02:18,050 Otherwise you will get topics that just won't be acceptable. 35 00:02:18,050 --> 00:02:20,390 And so the points you get on this homework 36 00:02:20,390 --> 00:02:23,950 is going to be based on how well you read that and can come up 37 00:02:23,950 --> 00:02:26,770 with some topics, even if you decide 38 00:02:26,770 --> 00:02:28,260 it's not your final topic. 39 00:02:28,260 --> 00:02:29,950 Because then you have to start working. 40 00:02:37,600 --> 00:02:41,960 We will ask for a final decision about your topic later, 41 00:02:41,960 --> 00:02:46,080 and then you'd better get busy on the reports. 42 00:02:46,080 --> 00:02:46,701 Yes? 43 00:02:46,701 --> 00:02:48,054 AUDIENCE: When is the quiz? 44 00:02:48,054 --> 00:02:48,960 Is that next week? 45 00:02:48,960 --> 00:02:51,168 PROFESSOR: The quiz, I think, will be next Wednesday. 46 00:03:00,960 --> 00:03:02,840 As you've probably realized already 47 00:03:02,840 --> 00:03:05,030 from what I've said about sociobiology 48 00:03:05,030 --> 00:03:09,000 and from your reading of Alcock, sociobiology 49 00:03:09,000 --> 00:03:15,260 has led to a lot of changes in the reports occurring 50 00:03:15,260 --> 00:03:17,620 in the literature, and the number of people studying 51 00:03:17,620 --> 00:03:20,120 animal behavior, and the topics they're working on. 52 00:03:24,660 --> 00:03:27,080 So that's the first thing I want to talk about. 53 00:03:27,080 --> 00:03:29,190 We've mentioned it already. 54 00:03:29,190 --> 00:03:31,950 And then we'll be talking about more examples of things 55 00:03:31,950 --> 00:03:34,880 that could be considered Darwinian puzzles-- things that 56 00:03:34,880 --> 00:03:38,200 probably wouldn't have been worked on-- nobody 57 00:03:38,200 --> 00:03:40,180 would have even have thought to work on 58 00:03:40,180 --> 00:03:46,350 without the ideas of sociobiology. 59 00:03:46,350 --> 00:03:50,340 So what were the big changes in animal behavior research 60 00:03:50,340 --> 00:03:51,730 after about 1970? 61 00:03:51,730 --> 00:03:56,480 This was all after the publication 62 00:03:56,480 --> 00:04:00,260 of this book Adaptation and Natural Selection 63 00:04:00,260 --> 00:04:01,910 by George C Williams. 64 00:04:01,910 --> 00:04:04,820 In other words, the changes started before the publication 65 00:04:04,820 --> 00:04:08,380 of the book Sociobiology by EO Willson. 66 00:04:08,380 --> 00:04:11,470 It was really George Williams that got that all started. 67 00:04:15,050 --> 00:04:18,880 And the stress was on adaptation. 68 00:04:21,910 --> 00:04:24,070 Why is this behavior adaptive? 69 00:04:24,070 --> 00:04:25,750 In other words, ultimate questions 70 00:04:25,750 --> 00:04:28,280 about the behavior, not just proximate questions 71 00:04:28,280 --> 00:04:34,910 about the sensory processes, the hormonal changes that cause it, 72 00:04:34,910 --> 00:04:38,140 details of fixed-action patterns, and so forth. 73 00:04:38,140 --> 00:04:43,350 And according to Alcock, the change 74 00:04:43,350 --> 00:04:48,640 was so dramatic that he looked at articles 75 00:04:48,640 --> 00:04:54,140 that appeared in the year 1970 and the year 1995 76 00:04:54,140 --> 00:04:55,495 in the journal Animal Behavior. 77 00:04:58,520 --> 00:05:00,950 And he's got his table there. 78 00:05:06,410 --> 00:05:09,350 Here's page 95 there. 79 00:05:12,260 --> 00:05:18,560 72% of the articles were on proximate questions 80 00:05:18,560 --> 00:05:20,530 in animal behavior in 1970. 81 00:05:20,530 --> 00:05:24,610 Only 16% in 1995. 82 00:05:24,610 --> 00:05:28,140 Pretty dramatic shift. 83 00:05:28,140 --> 00:05:29,575 Dealing with sensory and hormonal, 84 00:05:29,575 --> 00:05:31,800 if you just limit yourself to those kinds 85 00:05:31,800 --> 00:05:36,430 of proximate questions, 44% of them 86 00:05:36,430 --> 00:05:38,432 were on those topics in 1970. 87 00:05:38,432 --> 00:05:44,450 None of them in 1995. 88 00:05:44,450 --> 00:05:48,640 Whereas articles dealing with the adaptive basis of mate 89 00:05:48,640 --> 00:05:51,910 choice-- just that one topic, which was one of the big topics 90 00:05:51,910 --> 00:05:59,790 in sociobiology-- one article-- 4%-- in 1970. 91 00:05:59,790 --> 00:06:07,340 Went up to 54%-- 20 articles-- in '95. 92 00:06:07,340 --> 00:06:12,820 Now was the change really so extremely dramatic? 93 00:06:12,820 --> 00:06:15,710 Well, remember, they're just looking at the journal Animal 94 00:06:15,710 --> 00:06:17,680 Behavior. 95 00:06:17,680 --> 00:06:20,080 Proximate questions have continued 96 00:06:20,080 --> 00:06:24,180 to be very important in studies of animal behavior. 97 00:06:24,180 --> 00:06:27,980 But some of that has shifted more towards neuroethology. 98 00:06:27,980 --> 00:06:31,390 People in this department work on bird behavior 99 00:06:31,390 --> 00:06:34,260 and on mouse and rat behavior. 100 00:06:34,260 --> 00:06:36,400 But of course they're studying brain mechanisms, 101 00:06:36,400 --> 00:06:38,840 and their biggest interest is in brain mechanisms. 102 00:06:38,840 --> 00:06:43,730 But they also contribute to the study of behavior. 103 00:06:46,305 --> 00:06:51,370 All right what was the view of evolution 104 00:06:51,370 --> 00:06:55,320 presented by Konrad Lorenz? 105 00:06:55,320 --> 00:07:00,050 And especially in this earlier book, On Aggression? 106 00:07:00,050 --> 00:07:04,130 That was a book that became very popular and very controversial. 107 00:07:07,230 --> 00:07:14,620 And it was a mistaken view, and this is the way I describe it. 108 00:07:14,620 --> 00:07:20,040 He wrote about species benefits very much 109 00:07:20,040 --> 00:07:24,460 against George C Williams in '66, 110 00:07:24,460 --> 00:07:26,600 who had argued for the dominance and evolution 111 00:07:26,600 --> 00:07:31,880 of individual benefits-- survival and propagation 112 00:07:31,880 --> 00:07:36,040 of the specific genes carried by the individual. 113 00:07:36,040 --> 00:07:39,270 So the question is, why didn't that mistake 114 00:07:39,270 --> 00:07:41,570 impede Konrad Lorenz? 115 00:07:41,570 --> 00:07:43,780 And of course, the reason is that he 116 00:07:43,780 --> 00:07:47,140 was focusing on the proximate questions. 117 00:07:47,140 --> 00:07:49,640 So it didn't matter what his view of evolution was. 118 00:07:56,490 --> 00:07:59,460 He had a-- you could call it a group selectionist 119 00:07:59,460 --> 00:08:03,340 approach to evolution in that book On Aggression. 120 00:08:07,280 --> 00:08:10,860 And he cites some of it in the book 121 00:08:10,860 --> 00:08:13,210 we've been reading, the Foundations of Ethology, 122 00:08:13,210 --> 00:08:14,020 his later book. 123 00:08:17,090 --> 00:08:22,360 On page 29 he says its explicit function 124 00:08:22,360 --> 00:08:27,480 was selected because of its species-preserving value. 125 00:08:27,480 --> 00:08:31,120 But when he writes about genetic variation-- which he knows 126 00:08:31,120 --> 00:08:33,830 is very important in evolution-- he 127 00:08:33,830 --> 00:08:36,309 does discuss the survival of individuals. 128 00:08:36,309 --> 00:08:39,970 You can find that early in the book, page 26. 129 00:08:39,970 --> 00:08:41,600 And he has this interesting quote 130 00:08:41,600 --> 00:08:46,210 from Eigen-- a quote from 1975-- "Life 131 00:08:46,210 --> 00:08:51,700 is a game in which nothing is stipulated but the rules." 132 00:08:51,700 --> 00:08:54,290 Well, when people make statements about life that way, 133 00:08:54,290 --> 00:08:56,740 they're being philosophers, and they 134 00:08:56,740 --> 00:09:00,380 can have very different things in mind. 135 00:09:00,380 --> 00:09:03,630 But that was the way Lorenz did realize 136 00:09:03,630 --> 00:09:08,950 that evolution was about rules. 137 00:09:08,950 --> 00:09:14,190 It's just followed rules-- coldly and without regard 138 00:09:14,190 --> 00:09:20,470 to things that often human societies value. 139 00:09:20,470 --> 00:09:26,030 And this really wasn't so dissimilar to EO Wilson's book 140 00:09:26,030 --> 00:09:28,540 when he discusses the morality of the gene, which 141 00:09:28,540 --> 00:09:31,050 we've gone over before. 142 00:09:31,050 --> 00:09:33,020 He says that in a Darwinian sense, 143 00:09:33,020 --> 00:09:35,410 the organism does not live for itself. 144 00:09:35,410 --> 00:09:37,630 Its primary function is not even to reproduce 145 00:09:37,630 --> 00:09:38,940 with other organisms. 146 00:09:38,940 --> 00:09:40,990 It reproduces genes. 147 00:09:40,990 --> 00:09:43,560 We're just temporary carriers of genes. 148 00:09:43,560 --> 00:09:45,130 It's the genes that are evolving. 149 00:09:45,130 --> 00:09:48,270 And at first this seems ridiculous to me-- 150 00:09:48,270 --> 00:09:51,280 and I hope to you-- until you realize 151 00:09:51,280 --> 00:09:54,410 the purpose here from the standpoint 152 00:09:54,410 --> 00:09:57,400 of biological evolution is very restricted. 153 00:09:57,400 --> 00:10:00,310 Evolution follows a blind and simple rule. 154 00:10:02,900 --> 00:10:04,830 When we think about consciousness 155 00:10:04,830 --> 00:10:08,340 and the great ontological questions-- what are those? 156 00:10:08,340 --> 00:10:09,750 Why does anything exist? 157 00:10:09,750 --> 00:10:11,690 Why does consciousness exist? 158 00:10:11,690 --> 00:10:14,520 What is it? 159 00:10:14,520 --> 00:10:20,410 We're really placing ourselves outside the realm of that rule. 160 00:10:20,410 --> 00:10:25,690 So anyway, then Wilson goes on. 161 00:10:25,690 --> 00:10:27,370 What's in blue there is what I'm saying. 162 00:10:30,450 --> 00:10:34,540 He talks about brain mechanisms as just engineered 163 00:10:34,540 --> 00:10:35,740 to perpetuate DNA. 164 00:10:35,740 --> 00:10:37,700 And he's right from the standpoint 165 00:10:37,700 --> 00:10:39,140 of biological evolution. 166 00:10:39,140 --> 00:10:42,740 That's why the brain has evolved the way it did. 167 00:10:42,740 --> 00:10:45,710 But I just want to point out that Wilson was also, 168 00:10:45,710 --> 00:10:48,750 like Lorenz, group selectionist in his view. 169 00:10:48,750 --> 00:10:50,810 But in a way it was very different, 170 00:10:50,810 --> 00:10:55,210 because he knew a lot about molecular genetics. 171 00:10:55,210 --> 00:10:55,710 All right. 172 00:10:55,710 --> 00:11:01,160 So I've just highlighted from those quotes we saw before 173 00:11:01,160 --> 00:11:08,700 from Sociobiology that the ambivalences in organisms 174 00:11:08,700 --> 00:11:13,250 are due to these counteracting forces in evolution that 175 00:11:13,250 --> 00:11:15,370 have affected the way the brain is evolving. 176 00:11:15,370 --> 00:11:19,140 It didn't evolve to promote happiness and survival 177 00:11:19,140 --> 00:11:20,440 of the individual. 178 00:11:20,440 --> 00:11:23,580 It's just for maximum transmission 179 00:11:23,580 --> 00:11:26,780 of those controlling genes. 180 00:11:26,780 --> 00:11:31,230 And he likes to stress that some of these result 181 00:11:31,230 --> 00:11:37,650 from differences in what's adaptive for the individual 182 00:11:37,650 --> 00:11:39,880 and what's adaptive for the family, 183 00:11:39,880 --> 00:11:43,750 and what's about adaptive for the tribe, and so forth. 184 00:11:43,750 --> 00:11:45,610 Because he thinks a lot more of the group, 185 00:11:45,610 --> 00:11:48,510 and there is certainly good evidence-- especially 186 00:11:48,510 --> 00:11:50,900 for small groups-- that small groups did 187 00:11:50,900 --> 00:11:53,435 evolve as groups-- not just as individuals. 188 00:11:59,570 --> 00:12:02,820 William D Hamilton published another-- it wasn't just 189 00:12:02,820 --> 00:12:06,020 Williams that published these very influential papers that 190 00:12:06,020 --> 00:12:08,980 influenced the development of this field. 191 00:12:08,980 --> 00:12:13,250 William D Hamilton, again, before Sociobiology book 192 00:12:13,250 --> 00:12:19,690 was published, he published a very influential paper-- 193 00:12:19,690 --> 00:12:22,270 "The Genetical Evolution of Social Behavior" 194 00:12:22,270 --> 00:12:26,440 in the journal Theoretical Biology. 195 00:12:26,440 --> 00:12:30,440 And he had there an analysis of altruistic behavior 196 00:12:30,440 --> 00:12:35,020 of sterile workers in colonies of social insects. 197 00:12:35,020 --> 00:12:37,160 So I'm asking there what knowledge 198 00:12:37,160 --> 00:12:39,390 that had been unavailable to Darwin 199 00:12:39,390 --> 00:12:41,100 did Hamilton apply to the problem? 200 00:12:41,100 --> 00:12:44,290 Because this was a big problem for Darwin, too. 201 00:12:44,290 --> 00:12:47,600 He knew it was. 202 00:12:47,600 --> 00:12:50,160 How could you explain sterile worker groups? 203 00:12:55,690 --> 00:13:00,760 But what was the information that Hamilton had? 204 00:13:00,760 --> 00:13:06,890 Very simply, he knew about genes. 205 00:13:06,890 --> 00:13:10,320 Darwin didn't know about genes. 206 00:13:10,320 --> 00:13:13,930 He knew about inheritance. 207 00:13:13,930 --> 00:13:18,040 He knew it had to be something like that. 208 00:13:18,040 --> 00:13:25,990 But that field of genetics-- I mean what were the dates? 209 00:13:25,990 --> 00:13:30,090 He knew something about genetics, but very rudimentary. 210 00:13:30,090 --> 00:13:31,775 Nothing about individual genes. 211 00:13:31,775 --> 00:13:35,920 They couldn't count genes, nothing like that. 212 00:13:35,920 --> 00:13:38,560 So unlike Darwin, Hamilton had a knowledge of genes. 213 00:13:38,560 --> 00:13:41,280 He focused on the genetic consequences 214 00:13:41,280 --> 00:13:44,920 of extreme altruism. 215 00:13:44,920 --> 00:13:48,700 And he pointed out that in a colony of social insects, 216 00:13:48,700 --> 00:13:52,290 males are haploid. 217 00:13:52,290 --> 00:13:56,390 They only have one copy-- one allele-- at each gene site. 218 00:13:56,390 --> 00:13:58,830 The females are diploid. 219 00:13:58,830 --> 00:14:04,340 So if a queen's eggs are all fertilized by one male-- 220 00:14:04,340 --> 00:14:10,920 so the male has just got that one allele at each gene site. 221 00:14:10,920 --> 00:14:17,060 So that's going to come together with the female's diploid. 222 00:14:17,060 --> 00:14:19,460 So that will combine with the female's genes. 223 00:14:19,460 --> 00:14:26,820 And if the queen's eggs are fertilized by one male-- 224 00:14:26,820 --> 00:14:31,640 you have to assume that-- then sister offspring share 50% 225 00:14:31,640 --> 00:14:36,470 of the mother's genes, 100% of the father's genes-- 226 00:14:36,470 --> 00:14:40,700 and therefore, on average, 75% with each other. 227 00:14:40,700 --> 00:14:48,360 Sisters are 75% related to each other-- more related 228 00:14:48,360 --> 00:14:52,960 to their sisters than they are to their mother 229 00:14:52,960 --> 00:14:55,520 or their father. 230 00:14:55,520 --> 00:14:58,750 This should promote altruistic behavior of female workers 231 00:14:58,750 --> 00:15:01,090 towards sisters who are future queens. 232 00:15:06,250 --> 00:15:07,700 At least some of those females. 233 00:15:07,700 --> 00:15:09,970 Many of the females, of course, will become workers. 234 00:15:09,970 --> 00:15:12,850 But some of them become future queens. 235 00:15:12,850 --> 00:15:17,460 And there, these are the workers are taking care of them. 236 00:15:17,460 --> 00:15:20,240 Because if they do that, then it increases the chances 237 00:15:20,240 --> 00:15:23,250 of reproduction of their own genes, 238 00:15:23,250 --> 00:15:26,600 which is what genetic fitness is. 239 00:15:26,600 --> 00:15:33,990 So we can ask what the alternatives to Hamilton's 240 00:15:33,990 --> 00:15:36,810 theoretical analysis in explaining 241 00:15:36,810 --> 00:15:39,440 the evolution of sterile worker class. 242 00:15:39,440 --> 00:15:44,240 And for a long time, nobody talked about alternatives. 243 00:15:44,240 --> 00:15:50,170 But then this paper in 2010 appeared. 244 00:15:50,170 --> 00:15:54,630 Notice that EO Wilson was one of the authors. 245 00:15:54,630 --> 00:15:59,940 "The Evolution of Eusociality." 246 00:15:59,940 --> 00:16:05,490 Wilson and two associates published it in Nature. 247 00:16:05,490 --> 00:16:09,930 They present an alternative to the inclusive fitness theory 248 00:16:09,930 --> 00:16:12,700 of Williams and Hamilton and others. 249 00:16:15,640 --> 00:16:26,910 And later Wilson and Wilson-- the other Wilson is not 250 00:16:26,910 --> 00:16:32,680 related to EO Wilson. 251 00:16:32,680 --> 00:16:36,180 "Thinking the Theoretical Foundations of Sociobiology." 252 00:16:36,180 --> 00:16:41,800 So Wilson had worked on this issue of alternatives 253 00:16:41,800 --> 00:16:50,660 to the inclusive fitness theory, and these authors 254 00:16:50,660 --> 00:16:54,370 discuss the rejection of group selection. 255 00:16:54,370 --> 00:16:57,040 And they present their argument for a return 256 00:16:57,040 --> 00:17:00,760 to more consideration of group selection ideas. 257 00:17:00,760 --> 00:17:05,490 And because of the importance of that, 258 00:17:05,490 --> 00:17:08,980 it's much harder to study. 259 00:17:08,980 --> 00:17:10,619 But anyway, I did post the article 260 00:17:10,619 --> 00:17:15,700 on Stellar, and to some of you, even in reports in the past 261 00:17:15,700 --> 00:17:23,069 I've had students that read that and find things related to it 262 00:17:23,069 --> 00:17:27,870 when they're trying to interpret social behavior. 263 00:17:32,060 --> 00:17:38,170 My next question concern a mammal-- the naked mole rat. 264 00:17:38,170 --> 00:17:41,580 I'm asking how are they similar to the hymenoptera-- that 265 00:17:41,580 --> 00:17:44,100 is, the social insects-- in a way that leads 266 00:17:44,100 --> 00:17:47,850 sociobiologists to predict extreme altruistic behavior 267 00:17:47,850 --> 00:17:49,450 in these animals. 268 00:17:49,450 --> 00:17:53,260 And it has to do with their social organization. 269 00:17:53,260 --> 00:17:57,580 They have a queen with several male consorts, 270 00:17:57,580 --> 00:18:00,270 and the workers are siblings or half-siblings. 271 00:18:03,311 --> 00:18:04,685 But they're actually more related 272 00:18:04,685 --> 00:18:08,480 than that would indicate, because inbreeding is common, 273 00:18:08,480 --> 00:18:12,880 and it increases genetic relatedness. 274 00:18:12,880 --> 00:18:16,420 And that leads to the prediction of more extreme 275 00:18:16,420 --> 00:18:19,700 altruistic behavior than you would get otherwise. 276 00:18:19,700 --> 00:18:23,250 And the studies of the naked mole rat have supported that. 277 00:18:23,250 --> 00:18:28,050 They will, to defend, their queen, defend each other, 278 00:18:28,050 --> 00:18:31,955 they will die in their tunnels preventing an intruder 279 00:18:31,955 --> 00:18:35,070 from getting in-- just one example 280 00:18:35,070 --> 00:18:39,325 of the extreme altruistic behavior that they show. 281 00:18:39,325 --> 00:18:45,430 This is an animal that humans can't help but think 282 00:18:45,430 --> 00:18:48,470 of as being ugly, but I'm sure to another mole rat 283 00:18:48,470 --> 00:18:49,140 they're not. 284 00:18:52,710 --> 00:18:54,650 Let's go to some of these puzzles 285 00:18:54,650 --> 00:18:58,000 that sociobiologists have tackled, 286 00:18:58,000 --> 00:19:00,710 and sometimes they didn't even recognize 287 00:19:00,710 --> 00:19:03,050 because nobody had looked for them. 288 00:19:03,050 --> 00:19:08,950 Trivers and Hope Hare wrote an article in 1976 289 00:19:08,950 --> 00:19:11,660 predicting that in colonies of social insects, 290 00:19:11,660 --> 00:19:13,910 workers would care more for future queens 291 00:19:13,910 --> 00:19:17,330 than for future drones-- and we talked just briefly 292 00:19:17,330 --> 00:19:21,200 about that-- because of these genetics we mentioned. 293 00:19:21,200 --> 00:19:24,630 Fertilized eggs produce females, unfertilized eggs 294 00:19:24,630 --> 00:19:25,600 produce males. 295 00:19:28,960 --> 00:19:32,820 One result is that the female's more closely related 296 00:19:32,820 --> 00:19:35,630 to her sisters-- which we pointed out-- 297 00:19:35,630 --> 00:19:40,350 than she is to her daughters as well as to her brothers. 298 00:19:40,350 --> 00:19:42,570 Thus a female worker's genetic fitness 299 00:19:42,570 --> 00:19:44,680 benefits more if she raises sisters 300 00:19:44,680 --> 00:19:47,740 than if she raises brothers or daughters. 301 00:19:47,740 --> 00:19:51,620 And I just point out that it gives 302 00:19:51,620 --> 00:19:54,560 a reason why a sterile worker caste could evolve 303 00:19:54,560 --> 00:19:57,170 in the first place in social insects. 304 00:19:57,170 --> 00:20:00,720 It was because of this method of reproduction. 305 00:20:05,250 --> 00:20:08,940 Then the other discoveries were made. 306 00:20:08,940 --> 00:20:11,875 Ant workers and other social insect. 307 00:20:15,491 --> 00:20:19,390 And I'm asking, why should it matter 308 00:20:19,390 --> 00:20:23,260 to the workers of the European wood ant 309 00:20:23,260 --> 00:20:27,940 whether their mother mates with one male or with several, 310 00:20:27,940 --> 00:20:31,660 just to make a point about the nature 311 00:20:31,660 --> 00:20:34,970 of this kind of reproduction. 312 00:20:34,970 --> 00:20:38,390 Because the ant workers behave very differently 313 00:20:38,390 --> 00:20:43,151 if their mother has just one mate or more than one mate. 314 00:20:45,800 --> 00:20:49,780 And that was very puzzling to people when it was discovered. 315 00:20:49,780 --> 00:20:53,690 So how do you solve the puzzle? 316 00:20:53,690 --> 00:20:56,370 It's a Darwinian puzzle. 317 00:20:56,370 --> 00:20:59,750 And you solve it by gene calculations. 318 00:20:59,750 --> 00:21:02,990 The gene calculations are very different if she 319 00:21:02,990 --> 00:21:04,970 mates with one male or more than one. 320 00:21:04,970 --> 00:21:07,710 If there's just one male, then the female workers, 321 00:21:07,710 --> 00:21:11,580 as we said before, share up to 75% of genes with sisters, 322 00:21:11,580 --> 00:21:13,560 only 25% with brothers. 323 00:21:16,820 --> 00:21:20,150 If there's two males, then the workers, who are half-sisters, 324 00:21:20,150 --> 00:21:24,660 share only 25% of genes-- the same as with their brothers. 325 00:21:27,740 --> 00:21:31,120 And somehow the workers know, because proportional investment 326 00:21:31,120 --> 00:21:35,710 in females by workers does depend on the mother's mating 327 00:21:35,710 --> 00:21:38,230 status. 328 00:21:38,230 --> 00:21:42,680 The sisters get more care only if the mother is monogamous-- 329 00:21:42,680 --> 00:21:45,100 not if she's got more than one mate. 330 00:21:50,390 --> 00:21:52,330 Alcock points out that no one would ever 331 00:21:52,330 --> 00:21:54,190 look for such a thing if they had not 332 00:21:54,190 --> 00:21:58,500 been educated by Hamilton and Williams. 333 00:21:58,500 --> 00:22:01,670 And these references are in the back of your book. 334 00:22:01,670 --> 00:22:06,550 They're two key articles-- the founding articles 335 00:22:06,550 --> 00:22:14,300 of this whole field that EO Wilson reviewed in his big book 336 00:22:14,300 --> 00:22:14,860 in '75. 337 00:22:22,290 --> 00:22:28,760 And this is a paper in '96 that presented that discovery. 338 00:22:31,850 --> 00:22:34,510 Similar-- and I think even more surprising-- 339 00:22:34,510 --> 00:22:38,946 is behavior of red fire ant colonies 340 00:22:38,946 --> 00:22:40,320 if they have more than one queen. 341 00:22:42,850 --> 00:22:44,750 This one's even stranger. 342 00:22:44,750 --> 00:22:46,870 Only queens that are heterozygous 343 00:22:46,870 --> 00:22:49,280 for one particular gene are allowed 344 00:22:49,280 --> 00:22:53,150 to survive and reproduce. 345 00:22:53,150 --> 00:22:56,055 Well, of course it wouldn't matter 346 00:22:56,055 --> 00:22:58,840 if the ones that weren't heterozygous didn't survive. 347 00:22:58,840 --> 00:23:00,330 And that's true. 348 00:23:00,330 --> 00:23:02,760 This is the gene, GP9. 349 00:23:02,760 --> 00:23:07,195 And if you call the two alleles big B 350 00:23:07,195 --> 00:23:11,670 and little b-- b is the more recessive gene-- 351 00:23:11,670 --> 00:23:17,130 you only find the heterozygous queens in a breeding pool. 352 00:23:17,130 --> 00:23:21,540 The ones with the double recess there, they 353 00:23:21,540 --> 00:23:24,220 don't survive to reproductive age. 354 00:23:24,220 --> 00:23:26,040 But what about the others? 355 00:23:26,040 --> 00:23:34,210 There are workers with BB-- big B-- with only that one gene. 356 00:23:34,210 --> 00:23:36,770 There are workers like that, but you 357 00:23:36,770 --> 00:23:38,510 won't find queens like that. 358 00:23:38,510 --> 00:23:41,430 They're born, and they survive for a while, 359 00:23:41,430 --> 00:23:43,710 but they're attacked and killed by mobs 360 00:23:43,710 --> 00:23:46,220 of workers with the heterozygous genotype. 361 00:23:51,610 --> 00:23:59,740 And the workers that have that big B gene in double dose-- 362 00:23:59,740 --> 00:24:02,540 they don't participate in the mob. 363 00:24:02,540 --> 00:24:06,280 It's just the heterozygous ones. 364 00:24:06,280 --> 00:24:09,270 It's not clear-- at least not to me 365 00:24:09,270 --> 00:24:12,660 at the moment-- I don't know of studies that have ever 366 00:24:12,660 --> 00:24:15,440 been able to figure out the proximate mechanisms of how 367 00:24:15,440 --> 00:24:17,120 they do that. 368 00:24:17,120 --> 00:24:18,590 Obviously they have to detect. 369 00:24:18,590 --> 00:24:23,260 There must be some behavioral signs of it. 370 00:24:23,260 --> 00:24:26,450 Or it could be olfactory. 371 00:24:26,450 --> 00:24:29,200 But the behavior could not be explained 372 00:24:29,200 --> 00:24:34,100 without this gene-counting of the sociobiologist. 373 00:24:34,100 --> 00:24:35,576 Yes. 374 00:24:35,576 --> 00:24:39,720 AUDIENCE: Has a study been done if the homozygous dominance 375 00:24:39,720 --> 00:24:44,520 of allele-- or homozygous dominance queens had been 376 00:24:44,520 --> 00:24:47,439 preserved and had a colony of their own, what happens-- 377 00:24:47,439 --> 00:24:48,230 PROFESSOR: Exactly. 378 00:24:48,230 --> 00:24:50,670 That would be a good experiment. 379 00:24:50,670 --> 00:24:52,410 Now if you can find a paper on that, 380 00:24:52,410 --> 00:24:54,240 you've got a great report. 381 00:24:54,240 --> 00:24:57,500 But I haven't checked for that. 382 00:24:57,500 --> 00:24:59,870 But it's a very good question. 383 00:24:59,870 --> 00:25:05,010 It's an area that's sort of crying 384 00:25:05,010 --> 00:25:09,510 for more experimental work of that nature. 385 00:25:09,510 --> 00:25:12,010 And you're giving an experiment you 386 00:25:12,010 --> 00:25:15,150 could do without doing some of these proximate things 387 00:25:15,150 --> 00:25:18,410 that we're talking about, trying to look at how did they even 388 00:25:18,410 --> 00:25:21,470 know which of the females were like that. 389 00:25:24,310 --> 00:25:27,900 Let's go to a simpler type of thing. 390 00:25:27,900 --> 00:25:34,810 And this is the explanation for why a male damselfly stays 391 00:25:34,810 --> 00:25:39,080 near a female he's mated, rather than just fly off in search 392 00:25:39,080 --> 00:25:41,050 of other females to mate with. 393 00:25:41,050 --> 00:25:42,940 He's perfectly capable of doing that. 394 00:25:42,940 --> 00:25:46,790 There are other females around. 395 00:25:46,790 --> 00:25:51,570 George Parker in 1970-- I started 396 00:25:51,570 --> 00:25:54,020 to call him George, because I know a famous George 397 00:25:54,020 --> 00:25:59,550 Parker much earlier century, but I'm not 398 00:25:59,550 --> 00:26:02,940 sure what his first name was, but Parker in 1970 399 00:26:02,940 --> 00:26:05,120 called this phenomenon-- what? 400 00:26:05,120 --> 00:26:07,210 He called it mate-guarding. 401 00:26:07,210 --> 00:26:09,350 Because that's what the male is doing. 402 00:26:09,350 --> 00:26:13,110 He's guarding his mate from other males, 403 00:26:13,110 --> 00:26:18,330 preventing her from copulating with other males. 404 00:26:18,330 --> 00:26:21,180 He stays with her right up to the point 405 00:26:21,180 --> 00:26:24,260 where she lays her eggs. 406 00:26:24,260 --> 00:26:27,511 She lays them in the water. 407 00:26:27,511 --> 00:26:31,700 And you will see the males following that female. 408 00:26:31,700 --> 00:26:33,420 You'll see them in the branches of trees 409 00:26:33,420 --> 00:26:36,320 over the water over the streams where they're laying eggs. 410 00:26:36,320 --> 00:26:39,840 And it's only after she's laid all her eggs 411 00:26:39,840 --> 00:26:41,980 that they would leave. 412 00:26:41,980 --> 00:26:43,880 Would you expect it to be widespread 413 00:26:43,880 --> 00:26:47,790 across various species? 414 00:26:47,790 --> 00:26:50,840 And you'd have to say yes-- if the female 415 00:26:50,840 --> 00:26:53,140 will remain receptive after mating 416 00:26:53,140 --> 00:26:55,030 and still could be impregnated. 417 00:26:55,030 --> 00:26:58,090 It's all related to genetic fitness. 418 00:26:58,090 --> 00:27:04,880 The male does it to increase his own fitness. 419 00:27:04,880 --> 00:27:05,870 What about the female? 420 00:27:05,870 --> 00:27:10,170 It actually might benefit her to mate with more than one male. 421 00:27:10,170 --> 00:27:12,650 Maybe more of her eggs would hatch, like those birds 422 00:27:12,650 --> 00:27:15,350 we talked about last time. 423 00:27:15,350 --> 00:27:19,530 But now we're talking about the genetic interests-- 424 00:27:19,530 --> 00:27:22,840 genetic fitness interests-- of the male-- why 425 00:27:22,840 --> 00:27:25,830 he engages in mate-guarding. 426 00:27:25,830 --> 00:27:27,790 And yes, you do find it. 427 00:27:27,790 --> 00:27:28,860 This is the damselfly. 428 00:27:32,670 --> 00:27:36,900 Type of dragonfly really, at least similar to dragonflies. 429 00:27:42,820 --> 00:27:48,550 Let's go to another topic now-- in fruit flies. 430 00:27:48,550 --> 00:27:50,570 Why have male fruit flies evolved 431 00:27:50,570 --> 00:27:55,990 so they inject chemicals that harm their mate? 432 00:27:55,990 --> 00:28:01,890 They're toxic chemicals they inject along with their sperm. 433 00:28:01,890 --> 00:28:03,125 It's harmful to the female. 434 00:28:06,490 --> 00:28:09,570 How do you explain that in terms of evolutionary fitness, 435 00:28:09,570 --> 00:28:12,940 following the logic of George C Williams? 436 00:28:12,940 --> 00:28:14,860 What's the male interested in? 437 00:28:14,860 --> 00:28:19,570 He's interested in promoting his own genetic fitness-- not hers. 438 00:28:19,570 --> 00:28:24,250 But he needs the female to reproduce, right? 439 00:28:24,250 --> 00:28:27,750 So from the perspective of the male, what counts 440 00:28:27,750 --> 00:28:34,030 is the number of eggs capable of hatching that he inseminates. 441 00:28:34,030 --> 00:28:36,310 It's in the interests of his genes 442 00:28:36,310 --> 00:28:39,400 to destroy sperm from other males. 443 00:28:39,400 --> 00:28:42,120 And that's what he's doing by injecting that chemical 444 00:28:42,120 --> 00:28:50,000 before he mates-- even if injecting the chemical 445 00:28:50,000 --> 00:28:53,290 entails reducing the genetic fitness of the female 446 00:28:53,290 --> 00:28:55,840 by shortening her life or by reducing 447 00:28:55,840 --> 00:28:59,060 the total number of her eggs-- as long as the reduction is not 448 00:28:59,060 --> 00:29:00,440 extreme. 449 00:29:00,440 --> 00:29:04,740 Because if he doesn't do it, a lot more of her eggs 450 00:29:04,740 --> 00:29:06,525 could be fathered by other males. 451 00:29:10,590 --> 00:29:12,860 So that's how we have to interpret that. 452 00:29:21,050 --> 00:29:22,896 We met this phenomenon previously. 453 00:29:27,860 --> 00:29:30,220 The hanging fly-- do you remember? 454 00:29:30,220 --> 00:29:34,140 Randy Thornhill studied it, published back in '76. 455 00:29:34,140 --> 00:29:37,430 Why does the male present the receptive female 456 00:29:37,430 --> 00:29:40,350 with the gift of food, like a dead moth? 457 00:29:40,350 --> 00:29:44,840 There you see the female with a dead moth. 458 00:29:44,840 --> 00:29:46,230 That's not the male. 459 00:29:46,230 --> 00:29:50,680 That's the female that she's about to consume. 460 00:29:50,680 --> 00:29:53,525 And why does the gift have to be above a certain size? 461 00:29:56,270 --> 00:29:57,700 Why? 462 00:29:57,700 --> 00:29:59,560 Do you remember? 463 00:29:59,560 --> 00:30:01,020 We had several slides on it. 464 00:30:01,020 --> 00:30:04,290 It was in your reading. 465 00:30:04,290 --> 00:30:05,024 Yes. 466 00:30:05,024 --> 00:30:06,940 AUDIENCE: [INAUDIBLE] copulate with the female 467 00:30:06,940 --> 00:30:08,185 while she's eating. 468 00:30:08,185 --> 00:30:08,810 PROFESSOR: Yes. 469 00:30:08,810 --> 00:30:11,330 He copulates while she's eating. 470 00:30:11,330 --> 00:30:12,830 And the other thing you need to know 471 00:30:12,830 --> 00:30:18,250 is it takes quite a bit of time for him 472 00:30:18,250 --> 00:30:20,320 to inject all his sperm. 473 00:30:23,560 --> 00:30:27,850 And if the food's eaten before the male is finished-- 474 00:30:27,850 --> 00:30:31,360 and sometimes even before he's begun transferring sperm-- 475 00:30:31,360 --> 00:30:33,410 the female just uncouples, flies off 476 00:30:33,410 --> 00:30:36,940 to find a mate with a larger food offering. 477 00:30:36,940 --> 00:30:41,630 You see, it's not necessarily in her interest 478 00:30:41,630 --> 00:30:43,425 to mate with that particular male. 479 00:30:43,425 --> 00:30:45,920 It doesn't matter to her. 480 00:30:45,920 --> 00:30:49,200 She wants to produce her genes. 481 00:30:49,200 --> 00:30:53,220 The male wants to reproduce his. 482 00:30:53,220 --> 00:30:56,700 So after the sperm transfer is complete-- 483 00:30:56,700 --> 00:31:03,420 it takes 25 minutes-- then the behavior changes. 484 00:31:03,420 --> 00:31:04,890 In fact, the male and female often 485 00:31:04,890 --> 00:31:06,340 fight for the remaining food. 486 00:31:10,770 --> 00:31:12,750 Before, we said the male has a doggie bag, 487 00:31:12,750 --> 00:31:15,942 but actually the female can struggle with him 488 00:31:15,942 --> 00:31:18,050 for the remaining food. 489 00:31:18,050 --> 00:31:19,820 So the conclusion here of all this 490 00:31:19,820 --> 00:31:23,010 is that the interaction between male and female hanging flies 491 00:31:23,010 --> 00:31:27,600 is marked with genetic conflict as each individual jockeys 492 00:31:27,600 --> 00:31:32,170 for maximum personal reproductive gain, 493 00:31:32,170 --> 00:31:35,540 and thus maximum genetic success. 494 00:31:35,540 --> 00:31:39,060 Now this is the interpretation just based 495 00:31:39,060 --> 00:31:46,250 on individual genetic fitness, not on group selection at all. 496 00:31:46,250 --> 00:31:49,430 But that seems to be how you have 497 00:31:49,430 --> 00:31:53,975 to think to explain what's going on in these animals. 498 00:31:57,920 --> 00:32:01,850 So in studies of mate choice by females, 499 00:32:01,850 --> 00:32:05,140 which has occupied a lot of the sociobiological literature 500 00:32:05,140 --> 00:32:07,170 and the animal behavior literature 501 00:32:07,170 --> 00:32:17,200 since 1970-- Thornhill's papers on the topic of female choice-- 502 00:32:17,200 --> 00:32:19,860 and there were a number of them-- 503 00:32:19,860 --> 00:32:21,670 and the conflict between the sexes-- 504 00:32:21,670 --> 00:32:25,020 it marks the start of an era which still continues even 505 00:32:25,020 --> 00:32:29,530 now-- not just up to the time of Alcock's book-- 506 00:32:29,530 --> 00:32:32,810 in which these issues have been actively explored. 507 00:32:32,810 --> 00:32:36,690 A battalion of adaptationists who 508 00:32:36,690 --> 00:32:40,080 have adapted the gene-counting view of evolution 509 00:32:40,080 --> 00:32:44,210 are asking questions like how do female mating decisions promote 510 00:32:44,210 --> 00:32:47,060 the propagation of their genes? 511 00:32:47,060 --> 00:32:50,460 What exactly do females and their genes, of course, 512 00:32:50,460 --> 00:32:55,750 gain when females reject some males in favor of others? 513 00:32:55,750 --> 00:32:58,790 How do males manage to compete with rival males 514 00:32:58,790 --> 00:33:03,720 in a game whose rules were established by females? 515 00:33:03,720 --> 00:33:07,730 So we're talking about female mate choice, which 516 00:33:07,730 --> 00:33:11,613 is the most common type of mate choice. 517 00:33:16,140 --> 00:33:19,390 Sometimes the men in my class get quite deflated by all this, 518 00:33:19,390 --> 00:33:24,930 but I'm afraid, I'm sorry, the majority here is females. 519 00:33:24,930 --> 00:33:27,430 All right. 520 00:33:27,430 --> 00:33:32,940 Let's talk about the phenomena of cryptic female choice, which 521 00:33:32,940 --> 00:33:34,995 came up once before just briefly. 522 00:33:37,550 --> 00:33:39,780 What do we mean by cryptic female choice? 523 00:33:39,780 --> 00:33:44,852 And when we talked about it before, 524 00:33:44,852 --> 00:33:46,060 I don't know if you remember. 525 00:33:46,060 --> 00:33:46,893 There were two ways. 526 00:33:46,893 --> 00:33:49,295 We talked about a bird, and we talked even about plants. 527 00:33:49,295 --> 00:33:51,650 And Alcock introduces it in his book 528 00:33:51,650 --> 00:33:56,170 with an example from botany, describing a female flower's 529 00:33:56,170 --> 00:33:58,840 response to pollen of various origins. 530 00:34:03,050 --> 00:34:08,810 The gene-counting view led botanists-- not just 531 00:34:08,810 --> 00:34:12,130 animal behaviorists-- to start thinking differently 532 00:34:12,130 --> 00:34:14,520 about plant reproduction. 533 00:34:14,520 --> 00:34:17,839 They thought about things that before that time had just 534 00:34:17,839 --> 00:34:18,505 been overlooked. 535 00:34:22,270 --> 00:34:25,570 They discovered the equivalent of sperm competition 536 00:34:25,570 --> 00:34:27,569 by chemicals released from pollen 537 00:34:27,569 --> 00:34:30,980 that landed on nearby parts of the style. 538 00:34:30,980 --> 00:34:33,860 In other words, if pollen from one tree lands 539 00:34:33,860 --> 00:34:39,500 on a tree in the blossoms, how does that pollen 540 00:34:39,500 --> 00:34:44,770 prevent other pollen from other trees carrying different genes 541 00:34:44,770 --> 00:34:50,920 from succeeding in inseminating that particular flower? 542 00:34:50,920 --> 00:34:56,250 Well, how about deposit some toxic chemicals that 543 00:34:56,250 --> 00:34:58,400 affects the others? 544 00:34:58,400 --> 00:35:01,460 They actually do that. 545 00:35:01,460 --> 00:35:04,590 And for the birds, this is the example we had before. 546 00:35:04,590 --> 00:35:07,990 Remember the female spotted sandpiper. 547 00:35:07,990 --> 00:35:11,130 She leaves her first mate with her first clutch of four eggs, 548 00:35:11,130 --> 00:35:14,940 and she flies off to establish a nest and a second clutch 549 00:35:14,940 --> 00:35:18,080 of another four eggs with another male. 550 00:35:18,080 --> 00:35:28,290 However, she may inseminate with the stored sperm 551 00:35:28,290 --> 00:35:30,820 from the first male instead of the second male. 552 00:35:30,820 --> 00:35:34,900 So she's just using the second male to rear more chicks. 553 00:35:34,900 --> 00:35:38,180 She leaves the first one, and he stays and takes care of those. 554 00:35:38,180 --> 00:35:46,270 So she now reproduces up to eight individuals-- 555 00:35:46,270 --> 00:35:49,130 four chicks in each nest. 556 00:35:49,130 --> 00:35:57,915 Each male reproduces either eight or only four-- 557 00:35:57,915 --> 00:36:01,150 if she actually mates with the second male. 558 00:36:01,150 --> 00:36:04,780 So the female is exerting choice, in other words, 559 00:36:04,780 --> 00:36:07,550 but it's cryptic choice. 560 00:36:07,550 --> 00:36:11,940 It's nothing evident from just observing the behavior. 561 00:36:11,940 --> 00:36:14,866 It's happening inside her. 562 00:36:17,510 --> 00:36:20,630 So related to that topic is a strategy 563 00:36:20,630 --> 00:36:23,130 that's evolved in females of many species. 564 00:36:23,130 --> 00:36:26,160 It's called last sperm precedence. 565 00:36:26,160 --> 00:36:30,130 It's based where the last sperm to enter 566 00:36:30,130 --> 00:36:35,410 has got the best chance of fertilizing the eggs. 567 00:36:37,980 --> 00:36:43,100 It's based on the ability of female birds to store sperm. 568 00:36:43,100 --> 00:36:45,250 In other words, the sperm doesn't get to the eggs 569 00:36:45,250 --> 00:36:46,350 right away. 570 00:36:46,350 --> 00:36:48,210 It takes quite a while. 571 00:36:48,210 --> 00:36:50,450 And they can store sperm in tubules 572 00:36:50,450 --> 00:36:53,490 near the junction of the vagina and uterus. 573 00:36:53,490 --> 00:36:56,790 They fill up from the back, so the last sperm in 574 00:36:56,790 --> 00:37:00,960 are the first to be released at the time of fertilization. 575 00:37:00,960 --> 00:37:05,150 Fertilization may not take place right away after the mating. 576 00:37:05,150 --> 00:37:08,990 But when the sperm are released so they can inseminate 577 00:37:08,990 --> 00:37:11,420 the eggs, it'll be that last sperm in. 578 00:37:11,420 --> 00:37:14,720 And as long as she can do that and store them in this way, 579 00:37:14,720 --> 00:37:16,960 then she can mate with a number of males 580 00:37:16,960 --> 00:37:23,230 constantly looking for better and better genes. 581 00:37:23,230 --> 00:37:27,980 So that's another way she's exerting choice. 582 00:37:27,980 --> 00:37:31,695 Not mate choice, behaviorally, but father choice. 583 00:37:35,040 --> 00:37:39,730 So then that raises this big question-- 584 00:37:39,730 --> 00:37:42,450 how have males evolved to counter 585 00:37:42,450 --> 00:37:44,430 these cryptic abilities of females? 586 00:37:47,220 --> 00:37:49,740 Because males aren't concerned with her genetic fitness. 587 00:37:49,740 --> 00:37:52,680 They're concerned with their own genetic fitness. 588 00:37:52,680 --> 00:37:56,720 We talked about dunnocks before when 589 00:37:56,720 --> 00:38:00,570 we were reading Scott's book. 590 00:38:00,570 --> 00:38:02,700 The male dunnock can increase the chances 591 00:38:02,700 --> 00:38:08,210 of successful fertilization by his sperm by two behaviors. 592 00:38:08,210 --> 00:38:11,580 One is simply frequent copulation. 593 00:38:11,580 --> 00:38:12,520 And he does it. 594 00:38:12,520 --> 00:38:14,730 It's enhanced when he notices his mate 595 00:38:14,730 --> 00:38:17,680 in the vicinity of another male. 596 00:38:17,680 --> 00:38:20,140 But because of last sperm precedence, 597 00:38:20,140 --> 00:38:26,800 he just has to mate with her more so he doesn't lose out 598 00:38:26,800 --> 00:38:28,580 in this sperm competition. 599 00:38:31,920 --> 00:38:36,670 And he also pecks at the cloaca region of the female 600 00:38:36,670 --> 00:38:40,780 before copulation, and the film studies 601 00:38:40,780 --> 00:38:45,030 have shown that there are contractions 602 00:38:45,030 --> 00:38:47,850 resulting in excretion of fluid. 603 00:38:47,850 --> 00:38:50,530 And they've looked at that fluid and it does contain sperm. 604 00:38:50,530 --> 00:38:54,470 So basically the pecking causes her to get rid 605 00:38:54,470 --> 00:39:01,010 of some of the previous semen that was put in there. 606 00:39:01,010 --> 00:39:05,350 The female actually can choose whether to allow that behavior. 607 00:39:05,350 --> 00:39:08,100 She doesn't always. 608 00:39:08,100 --> 00:39:10,150 But it is a ritual that they go through. 609 00:39:10,150 --> 00:39:14,460 And if she wants to mate with that next male, 610 00:39:14,460 --> 00:39:16,330 then she will engage in that ritual, 611 00:39:16,330 --> 00:39:19,940 and she will permit that pecking that 612 00:39:19,940 --> 00:39:25,760 will result in expulsion of previous sperm. 613 00:39:25,760 --> 00:39:28,710 So what other male strategies are there? 614 00:39:28,710 --> 00:39:31,570 Sperm removal we mentioned before. 615 00:39:31,570 --> 00:39:35,490 It's common among especially male invertebrates. 616 00:39:35,490 --> 00:39:38,300 Dragonflies and damselflies have penises 617 00:39:38,300 --> 00:39:40,710 covered with bristles and thorns that the male 618 00:39:40,710 --> 00:39:44,755 uses to scrub out the female before copulation. 619 00:39:48,870 --> 00:39:52,680 The male bean weevil has a different strategy. 620 00:39:52,680 --> 00:39:54,950 He's got a similar penis, but he uses 621 00:39:54,950 --> 00:39:58,210 it to lacerate the reproductive tract of the female 622 00:39:58,210 --> 00:40:00,030 during copulation. 623 00:40:00,030 --> 00:40:04,260 It's like the toxic insemination by the fruit flies, 624 00:40:04,260 --> 00:40:06,360 but this time they're injuring the female. 625 00:40:06,360 --> 00:40:07,770 Why would they do that? 626 00:40:07,770 --> 00:40:09,420 Well, it makes it much less likely 627 00:40:09,420 --> 00:40:13,500 that she'll copulate with another male. 628 00:40:13,500 --> 00:40:15,550 It's too painful. 629 00:40:15,550 --> 00:40:17,295 It does shorten the life of the female. 630 00:40:20,300 --> 00:40:22,110 They normally live about a month. 631 00:40:22,110 --> 00:40:26,330 It can shorten it to 10 days-- as much as 10 days, 632 00:40:26,330 --> 00:40:31,920 depending on how bad her injuries are. 633 00:40:31,920 --> 00:40:35,280 And the result is-- and this is what the behaviorists have 634 00:40:35,280 --> 00:40:43,980 observed-- they fight off male suitors, generally unwanted. 635 00:40:43,980 --> 00:40:46,070 But even if she had one of them before, 636 00:40:46,070 --> 00:40:49,920 she won't want them now because of these injuries. 637 00:40:49,920 --> 00:40:53,740 So it's kind of traumatic insemination. 638 00:40:53,740 --> 00:40:56,510 This is one of the animals that does that-- the bean weevil. 639 00:40:56,510 --> 00:40:58,770 It shows a female on a bean there. 640 00:41:03,052 --> 00:41:04,510 Often we use examples from beetles, 641 00:41:04,510 --> 00:41:08,622 because there's more beetles than any group in all 642 00:41:08,622 --> 00:41:14,030 of the whole animal kingdom. 643 00:41:14,030 --> 00:41:17,000 And you find examples of traumatic insemination 644 00:41:17,000 --> 00:41:19,390 like that in a number of other animals. 645 00:41:19,390 --> 00:41:21,430 The fruit flies we mentioned before. 646 00:41:21,430 --> 00:41:23,450 The bed bugs. 647 00:41:23,450 --> 00:41:24,630 These are bed bugs. 648 00:41:24,630 --> 00:41:28,110 I thought you might enjoy seeing some bed bugs here. 649 00:41:28,110 --> 00:41:30,110 In case you ever look for them, here 650 00:41:30,110 --> 00:41:33,690 they are the edge of a bed. 651 00:41:33,690 --> 00:41:38,050 If you have them, you need to do something to get rid of them. 652 00:41:38,050 --> 00:41:40,370 And then plant bugs and spiders. 653 00:41:40,370 --> 00:41:44,120 They've been found in all these groups of animals. 654 00:41:44,120 --> 00:41:46,720 And the bed bugs I first read about in this book 655 00:41:46,720 --> 00:41:49,370 by Wolfgang Wickler. 656 00:41:49,370 --> 00:41:52,740 Wickler in 1973 published a fascinating book 657 00:41:52,740 --> 00:41:54,500 that became quite popular. 658 00:41:54,500 --> 00:41:56,920 You might still find it in paperback. 659 00:41:56,920 --> 00:41:59,700 It's called The Sexual Code-- The Social 660 00:41:59,700 --> 00:42:06,490 Behavior of Animals and Men. 661 00:42:06,490 --> 00:42:14,260 It's translated into English, published by Doubleday. 662 00:42:14,260 --> 00:42:17,670 Early in the book, page 37, he has this description 663 00:42:17,670 --> 00:42:20,960 of the bed bugs' traumatic insemination. 664 00:42:20,960 --> 00:42:22,640 He has huge numbers of examples. 665 00:42:22,640 --> 00:42:26,830 You won't believe the variety in mating behavior 666 00:42:26,830 --> 00:42:29,250 in the nature of reproduction in different animals. 667 00:42:31,940 --> 00:42:36,920 When I first went up to the Museum of Comparative Zoology 668 00:42:36,920 --> 00:42:40,110 at the time when I was working on my thesis, 669 00:42:40,110 --> 00:42:43,625 and I was looking for articles I couldn't find at MIT, 670 00:42:43,625 --> 00:42:45,370 because Harvard has everything. 671 00:42:45,370 --> 00:42:48,020 At least it seems so. 672 00:42:48,020 --> 00:42:51,160 And a lot of them were in this area over at the museum. 673 00:42:51,160 --> 00:42:52,900 And I went through some of these articles 674 00:42:52,900 --> 00:42:58,910 in biological literature on animals' reproductive behavior. 675 00:42:58,910 --> 00:43:00,220 And it was amazing. 676 00:43:00,220 --> 00:43:06,220 The detailed studies of penis anatomy for example. 677 00:43:06,220 --> 00:43:09,910 Incredible variety you just wouldn't believe. 678 00:43:09,910 --> 00:43:13,210 And it raises this question right away-- why? 679 00:43:13,210 --> 00:43:13,710 Well. 680 00:43:13,710 --> 00:43:15,450 You begin to look at these insects 681 00:43:15,450 --> 00:43:18,110 and you begin to understand. 682 00:43:18,110 --> 00:43:19,750 It's so important in reproducing. 683 00:43:22,740 --> 00:43:26,140 So bed bugs are an example of a different kind 684 00:43:26,140 --> 00:43:32,950 of traumatic insemination, because they insert sperm 685 00:43:32,950 --> 00:43:35,870 into the body cavity of females without using 686 00:43:35,870 --> 00:43:36,920 the genital tract. 687 00:43:36,920 --> 00:43:41,150 They go right through the body wall. 688 00:43:41,150 --> 00:43:46,500 And that's led some females to evolve specialized body parts-- 689 00:43:46,500 --> 00:43:49,940 the parts which the males usually are attacking-- usually 690 00:43:49,940 --> 00:43:56,630 on their back-- to make it harder for the male to do that. 691 00:43:56,630 --> 00:43:58,050 Protect them from injury. 692 00:44:00,840 --> 00:44:02,850 She's trying to reduce the trauma. 693 00:44:02,850 --> 00:44:06,080 So you get this different kind of evolution 694 00:44:06,080 --> 00:44:09,230 of male and female. 695 00:44:09,230 --> 00:44:13,600 Now we're not talking about sexual selection 696 00:44:13,600 --> 00:44:14,780 in the usual way. 697 00:44:14,780 --> 00:44:17,820 We talked about sexual selection in terms of choice. 698 00:44:17,820 --> 00:44:19,810 Now we're talking about a different kind 699 00:44:19,810 --> 00:44:21,966 of sexual selection altogether. 700 00:44:25,280 --> 00:44:28,890 Different strategies of the two sexes. 701 00:44:31,820 --> 00:44:38,130 And this was an example I found a few years back about research 702 00:44:38,130 --> 00:44:41,710 with primates-- evidence for some kind 703 00:44:41,710 --> 00:44:44,160 of cryptic female choice. 704 00:44:44,160 --> 00:44:47,880 The paper was entitled "Selective Polyandry-- Female 705 00:44:47,880 --> 00:44:52,950 Choice and Intersexual Conflict in a Small Nocturnal Solitary 706 00:44:52,950 --> 00:44:53,450 Primate." 707 00:44:53,450 --> 00:44:54,625 And this is the summary. 708 00:44:57,530 --> 00:45:03,330 They were looking at this little primate, the gray mouse lemur. 709 00:45:03,330 --> 00:45:07,110 They were interested in the possible importance 710 00:45:07,110 --> 00:45:11,920 of female mating strategies realizing 711 00:45:11,920 --> 00:45:15,970 that her interests and the male interests could be different. 712 00:45:15,970 --> 00:45:19,300 And even though the males do try to dominate a female, 713 00:45:19,300 --> 00:45:23,820 they found that by gene-counting methods, they first 714 00:45:23,820 --> 00:45:26,400 of all-- behaviorally they found that the females mated 715 00:45:26,400 --> 00:45:31,480 with up to seven males up to 11 times with one male 716 00:45:31,480 --> 00:45:34,520 during the one night they become receptive. 717 00:45:34,520 --> 00:45:38,540 They have a very short period of receptivity. 718 00:45:38,540 --> 00:45:43,010 And so they often have more than one baby, 719 00:45:43,010 --> 00:45:45,820 and mixed paternity was common. 720 00:45:45,820 --> 00:45:50,380 But the heavier males sired more offspring. 721 00:45:50,380 --> 00:45:53,010 Even though you could observe this behaviorally, 722 00:45:53,010 --> 00:45:59,170 somehow the females were exerting some kind of choice. 723 00:46:02,660 --> 00:46:05,410 And so they might be mating. 724 00:46:05,410 --> 00:46:06,920 It looks behaviorally like they're 725 00:46:06,920 --> 00:46:09,085 mating all the time with one male. 726 00:46:09,085 --> 00:46:13,890 But even if they mate much less with some heavy male, 727 00:46:13,890 --> 00:46:17,410 he's more likely to be the father. 728 00:46:17,410 --> 00:46:19,090 So how does the female do it? 729 00:46:19,090 --> 00:46:21,800 It means they have to have mechanisms 730 00:46:21,800 --> 00:46:26,840 that have evolved to allow cryptic choice-- just 731 00:46:26,840 --> 00:46:27,745 like in those birds. 732 00:46:31,490 --> 00:46:36,330 Another discovery related to these sperm wars 733 00:46:36,330 --> 00:46:39,070 is the discovery of two kinds of sperm. 734 00:46:39,070 --> 00:46:42,010 They've been called eusperm and parasperm. 735 00:46:42,010 --> 00:46:44,890 They have different functions. 736 00:46:44,890 --> 00:46:50,580 This is one of the articles that was published online 737 00:46:50,580 --> 00:46:56,940 in 2006-- one of the early articles in this area. 738 00:46:56,940 --> 00:46:59,250 And this is a summary of that. 739 00:46:59,250 --> 00:47:01,230 They described sperm heteromorphism. 740 00:47:04,500 --> 00:47:08,950 They examine two female-centered hypotheses 741 00:47:08,950 --> 00:47:10,620 for the evolution and maintenance 742 00:47:10,620 --> 00:47:15,170 of this unconventional sperm production strategy. 743 00:47:15,170 --> 00:47:21,080 They used models to examine it, and then they 744 00:47:21,080 --> 00:47:23,230 were looking at it from the female point of view. 745 00:47:23,230 --> 00:47:24,890 So they're trying to figure out how 746 00:47:24,890 --> 00:47:31,290 this could be used by the female in her cryptic choice. 747 00:47:31,290 --> 00:47:37,510 But if you look into that-- how widespread 748 00:47:37,510 --> 00:47:41,340 is that phenomenon of sperm heteromorphism-- 749 00:47:41,340 --> 00:47:46,260 you find after 2001 it's been discovered 750 00:47:46,260 --> 00:47:47,970 in a host of animals. 751 00:47:47,970 --> 00:47:52,210 And we'll take a look at some of that next time. 752 00:47:52,210 --> 00:47:55,050 So we'll start with this topic. 753 00:47:55,050 --> 00:47:56,946 And then I will finish going through these. 754 00:47:56,946 --> 00:47:58,570 We'll finish reviewing the Alcock book. 755 00:47:58,570 --> 00:48:00,194 And then I'm going to go back to Wilson 756 00:48:00,194 --> 00:48:03,890 just to finish up the topics from Wilson, because I 757 00:48:03,890 --> 00:48:05,540 would like you to go over that. 758 00:48:05,540 --> 00:48:10,300 I'll put all the slides in one file, all the slides on Wilson.