On marriages in Britain, The Oxford Companion to Family and Local History notes several key points that dictated the age at which individuals married:
[T]he great majority of the people of Britain remained unmarried until
their mid-twenties. The proportion of males and females who married
before the age of 20 was always low....The restrictions of service and
apprenticeship, and the necessity to save enough money, prevented
earlier marriages even if the wish was there....Moreover, a large
number of people–at least one in six in the early modern period,
sometimes rising to one in four–never married.
The absence of a complete or even extensive dataset in eighteenth century Scotland containing marriage and fertility information makes it difficult to assess, at least definitively, subjects like average marriage age. Nevertheless, some attempts have been made.
In his essay titled "Age at Marriage of Scottish Women, circa 1660-1770", R. A. Houston describes how he used Scottish criminal court depositions to perfom an analysis of marriage trends, as they are one of the few sources to contain such information. Houston reports that the average age at marriage of women contained in this dataset was 26.6 years. He notes that there may be sources of bias inherent to the dataset. Houston also states that this figure is probably more representative of the Lowland Scotland marriage age for women, and there is some evidence that the average age may have been lower in Highland Scotland.
R. A. Houston's "Scottish Society, 1500-1800" is also worth a read. In this, he writes:
Key issues such as trends in nuptiality and fertility remain uncertain
because of the patchy survival and poor quality of essential sources
such as parish registers of baptisms, marriages and burials, but it is
argued that Scotland possessed a 'high pressure' demographic regime
similar to France or perhaps Ireland, where high birth rates were
matched by swingeing mortality, and where crises of subsistence
remained a central fact of life until the end of the seventeenth
century in the Lowlands and well into the eighteenth century in the
Highlands. Gibson and Smout imply in chapter 2 that the homeostatic
regime which adjusted population and resources in England (through
changes in the age of women at first marriage responding to the
standard of living) was not matched in Scotland...Scotland appears to
have resembled England in having a late age at first marriage for
women - 23 to 26 on average, though female celibacy was more
Ian Whyte notes in "Scottish Population and Social Structure in the Seventeenth and Eighteenth Centuries: New Sources and Perspectives":
It is evident, nevertheless, that some aspects of Scottish society and
demography correspond to patterns found in England and elsewhere in
north-west Europe. The basic age/sex structure of the population
derived from Webster is similar to England, as is household structure
and size. A relatively high age of first marriage for women linked to
the prevalence of farm and domestic service and a significant degree
of male and female celibacy occurred in both countries.
Although the linking of individuals between different sources is made
difficult by the limited range of Christian names and surnames in
Highland communities there is little doubt that the detailed study of
records of some of the larger Highland estates could provide further
information on population turnover in this region. The scale of
Scottish emigration to Ulster in the seventeenth century has long been
appreciated as has the extent of Scots mercenary service on the
continent. Such large-scale outflows of population must have been a
major check to demographic growth by removing from Scotland, sometimes
permanently, many young men thereby raising the age of first marriage
of women and the level of female celibacy.
In a footnote in Exploring the Scottish Past: Themes in the History of Scottish Society, citing data from Michael Flinn (see reference below), the author states:
Material on the subject is fragmentary for eighteenth-century
Scotland, but such data as do exist indicate substantially later ages
at marriage: a mean 'rural' age for women in Central Ayrshire of 26;
Laggan parish (Inverness) 29 to 32 for men and between 27 and 30 for
women; Lochcrutton (Kirkcudbright) average age at marriage 33 for men
and 24 for women.
Further works to explore include:
- Flinn, Michael W. 1976. Scottish population history: from the 17th
century to the 1930s. Cambridge: Cambridge University Press.
- Devine, T. M., and Rosalind Mitchison. 1998. People and society in Scotland. Vol. 1, Edinburgh: John Donald.
- Dixon, Ruth B. 1978. "Late Marriage and Non-Marriage as Demographic
Responses: Are They Similar?" Population Studies. 32 (3): 449.