244 
Duration of Life and Number of Offspring 
In these deferred expectations the correlation is very high and within very 
small limits of error, and again it is positive in both series for mothers of small 
families and negative for mothers of large families. We may therefore safely 
conclude that the advantage in longevity is distinctly in favour of mothers of 
moderate sized families of about six children, and that in New South Wales 
at all events, maximum fertility is extremely unfavourable to extreme longevity. 
I think the reasons are sufficiently obvious — and what applies to New South 
Wales must apply with equal force elsewhere — the incessant strain upon the 
physique of women who bear large families daring the periods of gestation, 
parturition and lactation must be very prejudicial to longevity, whilst the mental 
strain involved in the rearing of such families cannot be regarded as other 
than detrimental. But we are also presented with the fact that childless women 
and mothers of extremely small families have shorter expectation of life than 
mothers of moderate sized tamilies. This I consider must arise partly from the 
inferior physique of unprolific women generally, and partly — perhaps chiefly — 
in consequence of the prejudicial effects of the efforts to prevent and to limit 
families. But whatever may be the explanation, the shortened life thus occasioned 
is by no means equal to that occasioned by unrestrained excessive fertility. In 
New South Wales there is but little Malthusian restraint when compared with 
the old countries of the world — notwithstanding that the Government of that 
State, alarmed at the decline in the birthrate, appointed a Royal Commission 
to investigate the causes operating to produce such decline. In its Report, 
relying upon medical evidence and on statistics which I think were wrongly 
interpreted, it declared that there had been a serious decline and that this was 
chiefly to be attributed to artificial restraint. That there has been a decline 
in the birthrate, whether measured as per 1000 of the population, or per 1000 
married women of the reproductive period, or in age groups within that period, 
is obvious from the figures produced in evidence, but it was entirely overlooked 
when dealing with the latter method — the only correct one — that there had been 
a considerable change in the physique of the population. In the earlier days 
the community consisted chiefly of specially selected immigrants drawn for the 
most part from the most prolific classes of the British community, viz. the agri- 
cultural and artisan. Now that immigration has practically ceased, the birthrate 
has declined from an abnormal condition due to a differentiated community to 
that of a more normal population. That there is restriction to some extent 
amongst certain classes of the community is doubtless true — although it is equally 
probable that this has always been the case — but, as we shall subsequently see 
in another part of this paper*, the extent of this practice is very limited. 
It was previously remarked that the expectation or mean duration of life 
used throughout the investigation should not be mistaken for the actuarial 
expectation of life at the ages referred to. Thus according to the English 
Registrar-General's life table*}", the expectation of females aged 46 is 23'34 years, 
* See "Distribution of Fertility," p. 247. 
t Supplement to Fifty-fifth Annual Report, Part i. pp. xviii. and xix. 
