Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Late motherhood boosts family lifespan

05.05.2009
Same genes linked to longevity and births after age 45

Women who have babies naturally in their 40s or 50s tend to live longer than other women. Now, a new study shows their brothers also live longer, but the brothers' wives do not, suggesting the same genes prolong lifespan and female fertility, and may be more important than social and environmental factors.

"If women in your family give birth at older ages, you may well have a chance of living longer than you would otherwise," says the study's lead author, demographer Ken R. Smith, a professor of family and consumer studies at the University of Utah. "If you have a female relative who had children after age 45, then there may be some genetic benefit in your family that will enhance your longevity."

For descendants of the Utah and Quebec pioneers studied, "you may be able to look at the ages when your female ancestors gave birth – rather than just their longevity – in estimating how long you may live," says Smith, whose study will be published online May 4 and in the June 10 print issue of the Journal of Gerontology: Biological Sciences.

The researchers examined high-quality genealogical records from the Utah Population Database at the University of Utah with its records of 1.6 million Utah Mormon pioneers and their descendants. They also used the University of Montreal's Program on Demographic History Research, which has records on 400,000 people who lived in heavily Catholic Quebec between 1608 and 1850.

Specifically, the study involved the records of 11,604 Utah men who were born between 1800 and 1869 and who had at least one sister who lived at least to age 50; and the records of 6,206 Quebec men who lived between 1670 and 1750, and had at least one sister who lived to 50 or older. The key findings:

Women who had "late fertility" – a birth at age 45 or older – were 14 percent to 17 percent less likely to die during any year after age 50 than women who did not deliver a child after age 40. That confirmed earlier studies. But those studies did not determine if the women gave birth later and lived longer because of genes or because of social and environmental factors such as good nutrition or healthy living.

Brothers who had at least three sisters, including at least one sister who gave birth at age 45 or later, were 20 percent to 22 percent less likely to die during any year after age 50 than brothers who had no "late fertile" sisters. That indicates what earlier studies did not, namely, the same genes may influence the lifespan of both sexes and women's ability to give birth at older ages.

The brothers' wives didn't have longer lives, suggesting any environmental or social factors that influence lifespan had only a weak influence, and that genes may explain why brothers lived longer when they had a sister who gave birth in her 40s.

The study didn't address how much longevity is due to genetics, but Smith says scientists believe genes account for up to 25 percent of differences in longevity.

Smith conducted the study with two other University of Utah researchers: Richard Cawthon, a research associate professor of human genetics, and demographer Geraldine Mineau, a research professor and director of population sciences at the university's Huntsman Cancer Institute, where Smith also is an investigator. Other coauthors were demographer Alain Gagnon and sociologist Ryan Mazan of the University of Western Ontario, and demographer Bertrand Desjardins, of the University of Montreal.

Good Genes Versus a Good Environment

Smith says that during the last decade, "there have been several studies that show a number of species, including humans, are able to reproduce late without medical intervention – and those females live longer." Other studies found that late menopause also is associated with women having prolonged fertility and longevity.

"There is a genetic component to longevity, especially for living to very old ages," Smith says. "The new thing here is what most evolutionary biologists long have argued: that survival and reproduction are intrinsically linked to one another. So the novel finding in this paper is discovering this link in humans before modern contraception."

But he says the link between late motherhood and longevity "could be something that is not inherited. It could be good nutrition or really good living, suggesting that if you are a healthier mom you live longer."

That is why the researchers looked at the lifespan of the brothers of women who had babies late, and of those brothers' wives. The wives are not blood relatives, so genetic factors shared by sisters and brothers wouldn't be the same in the brothers' wives.

Smith says the study focused on the longevity of brothers rather than sisters of late-fertile women because "men's own reproductive history doesn't get in the way of assessing the role of their female relatives' fertility."

The study focused on the two pioneer groups not only because of the quality of the data but because of the absence of modern birth control and an unfavorable attitude toward natural family planning methods by Mormons and Catholics. Also, a link between late fertility and lifespan is easier to observe in large families with more sisters.

Since all of those studied are now dead, the researchers could look at the full length of their fertile periods and lives. "Not many data sets could do this," Smith says.

The researchers controlled for various factors that could skew the results. For example, they excluded any individuals who did not live to at least 50 because a husband's death at a younger age would influence his wife's child-bearing.

Late Babies Linked to Longer Life for Moms and Blood Uncles

The study confirmed earlier research showing that women who have babies late tend to live longer.

Compared with women who had their last baby before age 41, Utah pioneer women who had their last baby at age 41 to 44 were 6 percent less likely to die during any given year past age 50, and Utah pioneer women who had their final birth at age 45 or older were 14 percent less likely to die during any given year after age 50.

In other words, imagine woman A had her last baby at age 35, woman B had her last baby at 42 and woman C had her last baby at 46. Then at age 52 – or any other age past 50 – woman B would be 6 percent less likely to die than woman A, and woman C would be 14 percent less likely to die than woman A.

In Quebec, slightly different age groups were analyzed. Compared with younger mothers, women who had their last child between ages 42 and 44½ were 6 percent less likely to die during any given year past age 50, and women who had their last child at age 44½ or older were 17 percent less likely to die during any given year past age 50.

By looking at the brothers of women who had children late, the study suggests the same age-slowing genes may be responsible for both prolonged fertility in women and longer lifespan in both sexes. The effects of late fertility were strongest for brothers with at least three sisters because the larger the number of sisters, the more likely it is at least one will give birth in middle age.

So in the Utah group, brothers with three or more sisters – at least one of whom gave birth at age 45 or older – were 20 percent less likely to die during any given year after age 50 than men without late-fertile sisters.

In Quebec, brothers with three or more sisters – at least one of whom gave birth at age 44½ or older – were almost 23 percent less likely to die during any single year after age 50 than men without sisters who gave birth late.

It is possible social and environmental reasons – good water, good nutrition, a healthy environment – could explain why the brothers and their late-birthing sisters had longer lives. So the researchers also examined the longevity of the brothers' wives.

They found no increase in lifespan, indicating that heredity – far more than environmental factors – played a role in the prolonged fertility and longer lives of the women, and the longer lives of their brothers.

Smith says the new findings do not conflict with one of his earlier studies finding that having larger families reduced parents' lifespan. Both findings can operate together.

Lee Siegel | EurekAlert!
Further information:
http://www.utah.edu

More articles from Studies and Analyses:

nachricht Drone vs. truck deliveries: Which create less carbon pollution?
31.05.2017 | University of Washington

nachricht New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Supersensitive through quantum entanglement

28.06.2017 | Physics and Astronomy

X-ray photoelectron spectroscopy under real ambient pressure conditions

28.06.2017 | Physics and Astronomy

Mice provide insight into genetics of autism spectrum disorders

28.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>