34 Data for the Problem of Evolution in Man 
TABLE III. 
Births per 100 Husbands in Age Groups. Experience of Victoria 1897. 
Age Group 
Mean Annual 
Marriages 
Ante-nuptial 
Conceptions 
Unprejndiced 
Marriages 
Mean Annual Births 
from 9 to 12 months 
after Marriage 
Births per cent, 
of unprejudiced 
Marriages 
Under 20 
55 
29 
26 
2 
7-70 
20 and under 25 
1708 
591 
1117 
257 
23-00 
25 
30 
2751 
702 
2049 
743 
36-25 
30 
35 
1637 
334 
1303 
565 
43-35 
35 „ 
40 
717 
149 
568 
191 
33-63 
40 „ 
45 
266 
43 
223 
69 
30-94 
45 
50 
132 
16 
116 
26 
22-41 
50 
55 
95 
13 
82 
10 
12-19 
55 „ 
60 
70 
0 
70 
7 
10-00 
60 
65 
56 
2 
54 
1 
1-85 
65 „ 
70 
33 
1 
32 
1 
3-12 
70 
75 
19 
1 
18 
0 
0-00 
The equation to the curve, the uuit of x being five years, is 
/ rf< Nl-fiM , \ 4-3857 
y = 39-75^1 + 3.^^23] (i-iro33ij ' 
■with the mean at 3G'7l years and the mode at 32-41. The range is from 14-34 to 
87-57 years. 
Unfortunately we have not the New South Wales experience for comparison, 
but we can hardly doubt that the age of maximum fertility would be somewhat 
younger. 
An examination of E'igures 1 and 2 will show how very satisfactorily these 
curves of Type I.* express the biometric data thus found. 
They show quite clearly tiiat at any rate for the Anglo-Saxon race the view of 
Korosi that the fertility is greater the younger the wife is not correct. The 
woman reaches her greatest reproductive vigour between 24 5 and 27 years, accord- 
ing to the climate, and the man at about 32 years. As we shall see under 
Section C these appear also to be the ages in the two sexes of maximum physique. 
B. On tlie Correlation between the Duration of Life and the Number of 
Offspring. 
The importance of this correlation as a fundamental factor in the quantitative 
theory of evolution has already been insisted uponf. Another determination of 
* Phil. Trans., Vol. 186 a, p. 367. 
+ Data for the Problem of Evolution in Man, V. On the correlation between the Duration 
of Life and the Number of Offspring. Beeton, Yule and Pearson, R. S. Proc. Vol. lxvii. p. 159. 
