It's no secret that there is already a trend among young people toward later marriage. After rising precipitously for decades, the median age for first marriage is 28 for men and 26 for women today. Undoubtedly this shift is due to a number of factors, including the sexual revolution and better career opportunities for women, but the key has been the increase in life expectancy. In 1850 it averaged around 43 years, so individuals didn't have the luxury of waiting around to look for their "perfect soul mate." The goal instead was to have children early and hope for the best.
Now, not only do changes in lifestyle encourage later marriages, the biological imperative to reproduce can be made less urgent by science. New techniques to extend the reproductive functioning of ovaries have also been explored in recent years. For example, in November 2008 the first birth from a full ovary transplant was announced to the public, a promising sign for older women who are unable to conceive owing to menopause, cancer treatment, or other causes of ovarian failure. In this case, a 38-year-old woman from London who experienced ovarian failure in her teenage years, sending her into early menopause, received an ovary from her twin sister. This procedure could pave the way for more women to have ovaries removed and frozen along with their eggs, to be thawed later on when they choose to have a child.
As life expectancy increases, the age at which women will want to have children will likely continue to grow, thereby increasing demand for reproductive technology to add even more time to women's biological clocks. One possibility that could really change the rules of the game is the ability to grow eggs in the lab. This would entail taking tiny pieces of ovarian tissue through keyhole surgery, a minimally invasive technique that is less painful and requires less recovery time than regular surgery. The tissue, which contains thousands of immature eggs, would be frozen until the woman decided to have children, at which point scientists would stimulate the eggs in the lab to grow to the point where they could be fertilized. This method would allow women to avoid injecting themselves with hormones or having to undergo an uncomfortable procedure to harvest mature eggs. As procedures like this become simpler and less expensive, the era of the 70-year-old mom may not be far off! Today, that sounds strange, but in a world with 150-year life expectancies, it could be commonplace.
An intriguing possibility resulting from the ability to have children at later ages is large age gaps between siblings. At the moment, it is rare to have an age gap of more than twenty years between children of the same biological parents. In a future of extended health spans and reproductive time, the possibility for large age differences among siblings mushrooms—they could be separated by two years, 20 years, or even 50 or 70 years.
What effect will this have on the conflict and closeness in families? No one can tell, but it will certainly be profound. Though generally true that siblings close in age fight more in childhood but are closer as adults, elder siblings can help younger children cope with stress and manage their external relationships. But there is no precedent for the age gaps that the longevity revolution will make possible: Sibling relationships may well resemble child-aunt/uncle or child-grandparent relationships soon.
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