Our cognitive abilities tend to decline when we get older, as we have trouble remembering old facts and skills and learning new ones. But a little young blood reverses some ill effects of old age, at least in mice, researchers reported at the Society for Neuroscience conference last week.
Neuroscientist Saul Villeda and his team gave elderly mice infusions of blood from younger, sprightlier members of their species. The old mice fortified with young blood improved on learning and memory tasks, such as finding a platform submerged in water and getting conditioned (think Pavlov’s dogs) to fear situations associated with electric shocks.
The researchers chose to examine the sperm of crickets, because, as with humans, you can get samples of it without having the male come into contact with a female first.
What’s the News: You might already know that sperm, which can survive for only a few hours when exposed to the outside world, can live for several days in women after ejaculation. But did you know that an ant queen can fertilize her eggs with sperm she’s stored for up to 30 years? And that organisms as diverse as birds, reptiles, and insects can hang onto sperm and keep it fresh for days, weeks, or months?
Scientists studying this ability have been trying to figure out how females do it, and in a recent paper, researchers put forth evidence showing that the ladies may be arresting the aging process, by slowing down sperms’ metabolism.
If having kids has made you feel like less of a party animal, men, you now have some science backing you up. A new study following men from their single salad days through the early years of their children’s lives found that fathers had a steeper decline in testosterone levels than men who remained single and childless. Though previous studies had indicated that fathers had lower testosterone, this is the first study to look at men before and after fatherhood, showing that it’s not just that lower-testosterone males are more likely to become dads. (In fact, this study shows the opposite—it’s the hormone-pumped guys who are more likely to settle down with a partner and have kids.)
But testosterone declines naturally with age, and stress is known to contribute to cellular aging. Is the accelerated decline because zero sleep, frayed nerves, and other byproducts of procreating are making men old before their time? That’s a question for next time—this study doesn’t address the decline’s cause.
Image courtesy of edenpictures / flickr
What’s the News: The human brains, capable as it is of amazing mental feats, comes with a downside: it shrinks as we get older, contributing to memory loss, reduced inhibitions, and the other cognitive dysfunctions of age. But even chimpanzees, our closest living relatives, don’t suffer this sort of brain loss, according to a study published online yesterday in Proceedings of the National Academy of Sciences. This unusual shrinkage of the human brain, the researchers say, may be a result of our long lifespan. Read More
What’s the News: It turns out that humans aren’t too different from blue-footed boobies, at least when it comes to age and fertility. Researchers have recently discovered that the sperm of blue-footed boobies declines with age. And unlike humans, the blue feet of the boobies also fade with age, revealing that one reason why female boobies tend to mate with brighter-footed males is to ensure the robustness of the sperm and the health of their offspring. “The study provides us with a new way of looking at what lies behind sexual signals,” lead author Alberto Velando told TIME, “pointing to the importance of sexual selection in eliminating genetic mutations.” Read More
That’s the conclusion of a study by University of Pittsburgh scientists published this week in the Journal of the American Medical Association. The work reviewed the results of nine other studies over the years that included more than 34,000 people aged 65 or older. When they tallied the total results, the numbers jumped off the page:
Only 19 percent of the slowest walking 75-year-old men lived for 10 more years compared to 87 percent of the fastest walking ones. Only 35 percent of the slowest walking 75-year-old women made it to their 85th birthday compared to 91 percent of the fastest walkers. [Boston Globe]
The results aren’t a huge surprise (“duh” comes to mind). The researchers note that walking is controlled falling, involving fine muscle control and the synchronicity of several systems:
“Walking requires energy, movement control, and support and places demands on multiple organ systems, including the heart, lungs, circulatory, nervous, and musculoskeletal systems,” the authors wrote. “Slowing gait may reflect both damaged systems and a high energy cost of walking.” [Los Angeles Times]
The study, published in Nature this week, used the enzyme telomerase to stop and actually reverse the aging process in prematurely-aged mice.
Telomerase keeps chromosomes structurally sound by beefing up telomeres, the repetitive segments of junk DNA at the ends of chromosomes. Telomeres act as protective buffers for the chromosome’s working genes during cell division, when the chromosome is shortened and genetic material at the tips is lost.
For the new study, researchers created special mice whose telomerase activity could be switched on and off. When telomerase was turned off, the mice aged prematurely.
These animals age much faster than normal mice–they are barely fertile and suffer from age-related conditions such as osteoporosis, diabetes and neurodegeneration. They also die young. “If you look at all those data together, you walk away with the idea that the loss of telomerase could be a very important instigator of the ageing process,” says [lead author Ronald] DePinho. [Nature News]
Forensic scientists of the future may soon have a new tool at their disposal. Given a drop of blood, researchers in the Netherlands have roughly determined the age of the person it came from. But for now, it really is rough–the researchers found they could only estimate a person’s age to within 9 years.
Currently, a crime scene investigator who obtained a spot of blood can check its DNA to see if it matches a known suspect or someone in a law enforcement database, and can use the DNA to determine a few other characteristics like gender and eye color. But age is tougher to estimate. Lead researcher Manfred Kayser, who works on forensic molecular biology at Erasmus University Medical Centre, explains that the best methods of determining age rely on testing bones or teeth, but he wanted to find a method that didn’t require skeletal remains.
We can predict your chances of living exceptionally long, with 77 percent accuracy, by looking at 150 tiny genetic variants. That’s what researchers claimed in a Science paper that we described last week. Those predictive powers have left some feeling a little uneasy–and not just about what futures are buried in their genomes. Where the paper‘s authors saw correlations, some experts are now seeing errors from DNA testing chips.
No DNA chip is perfect; it can get things wrong as it sorts through hundreds of thousands of genetic variants. In fact, certain chips might even make the same error repeatedly. That could cause problems, because what looks like a genetic variant common to a group of people could instead just be an echoed flaw in one chip’s testing capabilities.
Newsweek, which broke this story, reports that the Boston University researchers who led the study did, in fact, use different chips, but not enough different chips to rule out this potential error. They used two different types of DNA chips to test the centenarian group (about 1,000 people whose ages ranged from 95 to 119): a 370 chip that examines 370,000 genetic variants and a 610-Quad that examines 610,000 variants. The control group (of about 1,200 younger people) was tested with those two chips and a few others, thus possibly hiding any shared errors.
UPDATE: Some experts are questioning the validity of this study, and are suggesting that technical errors skewed the results. Full coverage here.
If you want to know how to get old, it’s best to ask the experts. That’s what Paola Sebastiani, a researcher at Boston University School of Public Health, did; She decided to look at the genes of 1,055 people, many who had already seen their 100th birthday.
As described in a paper published in Science today, Sebastiani’s team found that they could predict a person’s “exceptional longevity” with 77 percent accuracy.
The researchers looked at small variants called single-nucleotide polymorphisms (or SNPs) on the centenarians’ genomes; Sebastiani found she could use 150 SNPs to predict who would live to such exceptional ages.