THE popular view that rising divorce rates and births outside marriage mean the Australian family is an endangered species has been challenged by a new study that shows the family isn't dead, just different. Yes, divorce rates are rising, a lot more Australians are not marrying, they are having fewer children and more of them are ex-nuptial, the Australian Institute of Family Studies research has found. And it concedes those findings raise the question, ''can the family survive?'' But its answer is a resounding yes. Peter McDonald, the institute's deputy director, sums up: ''While families today may be different in many ways from past families, this does not mean that families are on the way out. Indeed, some of the recent changes in families (later marriage and a higher proportion who never marry) represent a return to patterns of a century ago. ''Solo parent families also were just as prominent a century ago as they are today. Thus we constantly redefine families and their place in our lives, but families remain important to almost all of us,'' he says. The institute's research has found that while some of today's trends show a return to the past, the reasons for them are very different. For instance, in the past 20 years the proportion of one-parent families has been rising - 16.6 per cent in 1991, compared with 13.2 per cent in 1981 and 9.2 per cent in 1974. That's now about as common as 100 years ago - in the state of Victoria in 1891 16.7 per cent of all families with dependent children were headed by just one parent. But while today's statistics may be explained by rising divorce rates splitting families and the increase in children born to unmarried women, last century it was the higher death rates that commonly left one partner alone. Dr McDonald says the improvement in death rates probably has a bearing on another key statistic: divorce. These days about 37 per cent of Australian marriages end in divorce, while a century ago that figure was only about one per cent after 30 years of marriage. Yet death rates in those days meant fewer than half of all marriages would have both partners alive after 30 years anyway. Given the length of time today's couples can expect their lives together to last, perhaps it's not surprising divorce rates today are as high as they are, he says. The research also reveals some dramatic changes in social attitudes and the way Australians view de facto relationships and ex-nuptial births. The so-called ''shotgun marriage'', in which a pregnant bride headed for the altar, that was a fairly common event in the 70s has all but disappeared today. In 1991 only 1,100 women were pregnant when they married, compared with 13,000 in 1971. Australia's recession has also had an impact on family life - not just through the pressures that lead to rising divorce rates, but on the age at which children leave home. In the 1950s and 1960s children left home to get married, take up a job or go away to study. And as they married younger in those years, so did the age at which they moved out of mum and dad's house - 21.5 years for men and 20.2 years for women in 1950. In the 70s those reasons changed. More young people left home to live in de facto relationships while fewer left to marry and more left just to be independent. But the age at which they left stayed about the same. In the 80s more Aussie kids stayed at school for senior study and went on to tertiary education (numbers that have increased in the 90s with the rise in joblessness and pressure to be better qualified). Research has also found that de facto relationships and relationships in which the couple did not live together were common. But for those who do decide it'll be second time lucky, the statistical news isn't good. The divorce rate from remarriage is higher than that from first marriages - 38 per cent compared with 37 per cent - and it's rising.