Lecture Tim Dyson,iss,The Hague,The Netherlands,23 April 2009 part 2.mov — Transcript

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1. 0:00yes that's right and uh over here is is
2. 0:03more or less the end of the
3. 0:05transition no one alive in the world
4. 0:08today has experienced truly
5. 0:12pre-transitional
6. 0:14circumstances truly pre-transitional
7. 0:17conditions indeed I think it is hard for
8. 0:20any of us here to really imagine what
9. 0:24truly pre-transitional circumstances
10. 0:26would be like and yet these were the
11. 0:28circumstances that prevailed everywhere
12. 0:31250 years ago or
13. 0:33so however perhaps 20 to 30% of births
14. 0:39would be dead before reaching their
15. 0:41first birthday 20 to 30% dead before
16. 0:44their first
17. 0:46birthday
18. 0:48events crises like epidemics in
19. 0:51particular but also sometimes famines
20. 0:53were so frequent that adults could never
21. 0:57be very sure that they would survive
22. 0:59from one one year to the
23. 1:02next and women women might have I don't
24. 1:06know five six perhaps even seven live
25. 1:10births during the course of their
26. 1:13reproductive
27. 1:15lives so what do we take from that the
28. 1:18first thing is that life was highly
29. 1:20uncertain for
30. 1:23everyone women's lives in particular
31. 1:26were dominated by
32. 1:28childbearing pregnancy
33. 1:31lactation and the fact that fertility
34. 1:34per per woman was high ensured that the
35. 1:37age structure of the population was
36. 1:40young so before the transition over here
37. 1:43we're dealing with young population age
38. 1:45structures primarily because of high
39. 1:47levels of
40. 1:50fertility now in contrast if we think
41. 1:53about posttransitional conditions trans
42. 1:57conditions after the demographic
43. 1:58transition then it's very easy for us to
44. 2:02imagine what those conditions are like
45. 2:04because they characterize the society
46. 2:06for example uh this Society
47. 2:09here life is much more secure very much
48. 2:14more
49. 2:14secure indeed very few deaths occur
50. 2:18below age 50 only a tiny number
51. 2:21particularly in comparative
52. 2:24terms women may have uh a couple of
53. 2:28births perhaps less during the course of
54. 2:32their reproductive
55. 2:33lives and the fact that fertility is low
56. 2:37means that the age structure of the
57. 2:39population is now old so it is the
58. 2:42fertility decline of the demographic
59. 2:44transition above all which is
60. 2:47responsible for population aging it
61. 2:49would account for why for example the
62. 2:51population of the Netherlands now is
63. 2:53much older than it was 250 years
64. 2:57ago okay now now in many respects in
65. 3:02fact I think in an awful lot of respects
66. 3:05the demographic transition is a very
67. 3:07good thing it's an extremely positive
68. 3:10phenomena and I'll say some things about
69. 3:12that a little bit
70. 3:15later when we come to a posttransitional
71. 3:17circumstance or as populations move
72. 3:20through this transition so people's hold
73. 3:23on life their grasp on life becomes much
74. 3:27stronger and another important aspect of
75. 3:31the transition is that it represents a
76. 3:34huge increase in the efficiency of
77. 3:39reproduction so to illustrate this if we
78. 3:42go back to circumstances before the
79. 3:44transition and I'm simplifying for
80. 3:46because we have to if we go back to this
81. 3:48sort of situation
82. 3:49here then a woman might have to have six
83. 3:53births in order for two of them to
84. 3:56survive into
85. 3:58adulthood but after the transition they
86. 4:01can essentially achieve exactly the same
87. 4:04result by just having two births both of
88. 4:08which will survive so it's an incredible
89. 4:11increase in the efficiency of
90. 4:14reproduction moreover notice from what
91. 4:16I've said that there is little
92. 4:19difference in I'm simplifying again here
93. 4:22there is little difference in net
94. 4:25fertility before the transition and
95. 4:28after the transition
96. 4:30because roughly I underline the word
97. 4:32roughly two two adults produce two
98. 4:36births or less both before and after but
99. 4:40not during the transition so in
100. 4:43technical terms net fertility is fairly
101. 4:46similar before and after this stylized
102. 4:51transition however another
103. 4:54characteristic of the transition which
104. 4:57is shown of course in this stylized
105. 4:59diagram
106. 5:00is that the death rate comes down before
107. 5:03the birth
108. 5:04rate and this means that there is a very
109. 5:07long period when the birth rate is
110. 5:09higher than the death rate and therefore
111. 5:12the transition always involves a lengthy
112. 5:16period of population
113. 5:19growth now what do I mean by a lengthy
114. 5:21period I'm doing some work on this it's
115. 5:23a matter of judgment but I think if you
116. 5:25look at most European transitions which
117. 5:27are now complete as essentially you're
118. 5:30looking at something that's two
119. 5:32centuries long perhaps 250 years long it
120. 5:35depends how you define the start of of
121. 5:37the transition but we're dealing with
122. 5:40200 years more or less at
123. 5:42least but if you look at most modern
124. 5:46transitions you're dealing with a
125. 5:48shorter shorter transitions I would say
126. 5:51very roughly speaking probably 100 to
127. 5:53150 years in length but that's my
128. 5:56judgment and it rests amongst other
129. 5:58things upon accepting projections
130. 6:00because very few other populations have
131. 6:02actually gone through the whole
132. 6:06transition
133. 6:08moreover at the level of individual
134. 6:10couples at the level of individual uh
135. 6:14men and women
136. 6:16couples there is a correspondingly long
137. 6:19period during which there is an increase
138. 6:22in average family size if you like an
139. 6:25increase in net
140. 6:27fertility mainly because fewer children
141. 6:30die as mortality comes down that is as
142. 6:33the death rate comes down first within
143. 6:36the
144. 6:36transition there in our stylized
145. 6:41diagram now importantly in this context
146. 6:44and I think this is important for those
147. 6:46of us who believe very firmly in Family
148. 6:48Planning importantly in this context the
149. 6:52lagged adoption of birth control it is
150. 6:55lagged by the way but it's birth control
151. 6:58essentially which brings down the birth
152. 7:00rate here in the second part of the
153. 7:03transition that top curve there the
154. 7:06lagged adoption of birth control that
155. 7:09leads to the reduction of the birth rate
156. 7:12can be seen as an attempt to maintain
157. 7:15family size rather than decrease it I
158. 7:19owe that phrasing to David reher who's
159. 7:22an American demographer based in Madrid
160. 7:24but he he says
161. 7:26that the adoption of birth control
162. 7:30within the transition can be seen as an
163. 7:32attempt to maintain family size to what
164. 7:35it was
165. 7:36originally rather than to decrease it
166. 7:39and I think that's a very valuable way
167. 7:41of thinking about uh uh the the case if
168. 7:44you like for Family Planning and and the
169. 7:47adoption of one birth
170. 7:49control
171. 7:50okay
172. 7:52now in a few
173. 7:55places other than Europe but
174. 7:58particularly in Europe the transition is
175. 8:01now
176. 8:02complete okay but in the rest of the
177. 8:05world it began much later often in the
178. 8:0920th century and it's still happening to
179. 8:12varying degrees today so this is a
180. 8:14massive phenoma that is gradually
181. 8:17unfolding if you like to look at it
182. 8:18everywhere in differing ways and so here
183. 8:22we have uh the data that I was able to
184. 8:25find for the
185. 8:27Netherlands and you can certainly see I
186. 8:30hope the correspondence no sorry stick
187. 8:33with the Netherlands yeah for a moment
188. 8:35you can certainly see I hope uh the uh
189. 8:38well there is the country's individual
190. 8:40history in the individual years and as I
191. 8:43type them in some of the years meant
192. 8:45things to me the rate would go up or
193. 8:47down in a particular way but although
194. 8:50that is the individual history of the
195. 8:52Netherlands it's also the demographic
196. 8:54transition and it also shows you um the
197. 8:57same general form that we were looking