Scientists already knew that people tend to marry others who have similar characteristics, including religion, age, race, income, body type and education, among others.

In the new study, published in the journal Proceedings of the National Academy of Sciences, scientists show that people also are more likely to pick mates who have similar DNA. While characteristics such as race, body type and even education have genetic components, this is the first study to look at similarities across the entire genome.

"It's well known that people marry folks who are like them," said Benjamin Domingue, lead author of the paper and a research associate at CU-Boulder's Institute of Behavioral Science. "But there's been a question about whether we mate at random with respect to genetics."

For the study, Domingue and his colleagues, including CU-Boulder Associate Professor Jason Boardman, used genomic data collected by the Health and Retirement Study, which is sponsored by the National Institute on Aging.

The researchers examined the genomes of 825 non-Hispanic white American couples. They looked specifically at single-nucleotide polymorphisms, which are places in their DNA that are known to commonly differ among humans.

The researchers found that there were fewer differences in the DNA between married people than between two randomly selected individuals. In all, the researchers estimated genetic similarity between individuals using 1.7 million single-nucleotide polymorphisms in each person's genome.

The researchers compared the magnitude of the genetic similarity between married people to the magnitude of the better-studied phenomenon of people with similar educations marrying, known as educational assortative mating. They found that the preference for a genetically similar spouse, known as genetic assortative mating, is about a third of the strength of educational assortative mating.

The findings could have implications for statistical models now used by scientists to understand genetic differences between human populations because such models often assume random mating.

The study also forms a foundation for future research that could explore whether similar results are found between married people of other races, whether people also choose genetically similar friends, and whether there are instances when people prefer mates whose DNA is actually more different rather than more similar.

Taste buds -- yes, the same ones you may blame for that sweet tooth or French fry craving -- may in fact have a powerful role in a long and healthy life -- at least for fruit flies, say two new studies that appear in theProceedings of the National Academy of Sciences of the United States of America.

Researchers from the University of Michigan, Wayne State University and Friedrich Miescher Institute for Biomedical Research in Switzerland found that suppressing the animal's ability to taste its food -regardless of how much it actually eats -- can significantly increase or decrease its length of life and potentially promote healthy aging.

Bitter tastes could have negative effects on lifespan, sweet tastes had positive effects, and the ability to taste water had the most significant impact -- flies that could not taste water lived up to 43% longer than other flies. The findings suggest that in fruit flies, the loss of taste may cause physiological changes to help the body adapt to the perception that it's not getting adequate nutrients.

In the case of flies whose loss of water taste led to a longer life, authors say the animals may attempt to compensate for a perceived water shortage by storing greater amounts of fat and subsequently using these fat stores to produce water internally. Further studies are planned to better explore how and why bitter and sweet tastes affect aging.

"This brings us further understanding about how sensory perception affects health. It turns out that taste buds are doing more than we think," says senior author of the University of Michigan-led study Scott Pletcher, Ph.D., associate professor in the Department of Molecular and Integrative Physiology and research associate professor at the Institute of Gerontology.

"We know they're able to help us avoid or be attracted to certain foods but in fruit flies, it appears that taste may also have a very profound effect on the physiological state and healthy aging."

Pletcher conducted the study with lead author Michael Waterson, a Ph.D graduate student in U-M's Cellular and Molecular Biology Program.

"Our world is shaped by our sensory abilities that help us navigate our surroundings and by dissecting how this affects aging, we can lay the groundwork for new ideas to improve our health," says senior author of the other study, Joy Alcedo, Ph.D, assistant professor in the Department of Biological Sciences at Wayne State University, formerly of the Friedrich Miescher Institute for Biomedical Research in Switzerland. Alcedo conducted the research with lead author Ivan Ostojic, Ph.D., of the Friedrich Miescher Institute for Biomedical Research in Switzerland.

Recent studies suggest that sensory perception may influence health-related characteristics such as athletic performance, type II diabetes, and aging. The two new studies, however, provide the first detailed look into the role of taste perception.

"These findings help us better understand the influence of sensory signals, which we now know not only tune an organism into its environment but also cause substantial changes in physiology that affect overall health and longevity," Waterson says. "We need further studies to help us apply this knowledge to health in humans potentially through tailored diets favoring certain tastes or even pharmaceutical compounds that target taste inputs without diet alterations."