Scientists who want to understand why some of us are living longer and healthier traditionally focus on studying centenarians from the "blue zones" in the world such as Okinawa, Japan or Icaria, Greece, where residents regularly break records of longevity.
Irish bats biologist Ema Tayling thinks the answer can be found among the bats in the bell tower of the Gothic cathedral in Brittany, France. Every spring she and her team travel there to catch hundreds of brown bats for babies and mothers with mice-eyelids to collect their blood so they can arrange DNA. Given that mothers are repeatedly returned to their native places to supply babies, cathedrals offer a perfect environment for recycling the same bats and learning how old they are.
Teeling is convinced that these little bats of Myotis weighing at most 1
the molecular mechanisms that keep them healthy, says Telling, who recently launched Bat1K, an initiative to sort out the genomes of all 1300 bat species. Of particular interest are the telomere of the bats, the protective end caps of the chromosomes, which in most mammals – including humans – abate as they age.
But the telomere of Myotis myotis bats remain the same size year after year. To solve the mystery, they compared the 225 genes in the bats cell pathway to those of 52 other mammals and found two genes that exist only in bats and which, in their view, could correct the damage to DNA that occurs with aging ,
In an article published this month, they reported the sequence of 1.7 trillion base pairs of RNA of 150 bats to detect the small regulatory genes involved in these aging pathways. The future goal is to "Manipulate these pathways in humans through drugs or potentially gene therapy and ultimately to limit and delay aging-related diseases in humans," Teeling said.
Animals have long been a major part of medical research – more than 140,000 were used in the United States in 2107, according to the Ministry of Agriculture – testing everything from drugs to surgical techniques, before being tested in humans. But a new wave of researchers is looking at the unique biology of some animals to learn how we can live and thrive longer.
"The study of population aging has shifted its focus from increasing longevity to increasing our health, which is how long people can live in a healthy way," said Corina Ross, a topologist at the Texas Biomedical Research Institute in San Antonio. She studies aging in marmosets. "The goal is not to increase the number of 120-year-olds living in nursing homes. We want more 80- and 90-year-old children living alone. "
Scientists historically depend on worms and rodents for aging studies, but paper from the National Institute on Aging in 2017 makes the case focus more on the inhumane. primates who share 92% of the genes with humans and have an "aging process that looks very much like human experience."
Although the National Institutes of Health announced in 2015 that it would stop using chimpanzees in biomedical research, Researchers say rhesus Monkeys and marmosets are useful models to learn about the mechanisms that "lead to a reduction in age observed universally in species." as humans. Marmosets can live up to 22 years old, but show signs of aging, such as stretching more and less rarely jumping from branch to branch, as early as 10 years.
"They are aging five times faster than humans. This means that we can investigate aging interventions in a much shorter time than in humans, "says Ross. For example, she assesses the effect on marmosets of an immunosuppressive drug called rapamycin, which has been shown to prolong the life of mice to see if it can slow down the cognitive decline and weakness of the monkeys. aging women because they have a similar reproductive cycle and offer opportunities to study what happens after menopause. Female rhesus monkeys, in particular, have a 28-day menstrual cycle and experience the end of their fertility around the same point in their life. (They live up to 40 years in captivity)
Neurologist Yuko Hara was curious about why some female rhesus monkeys are mentally sharper than other monkeys as they age and whether estrogen can play a role. In her study at Ikan Medical School in Mount Sinai, she and her team found that apes who had been given post-menopausal hormone therapy had better cognitive work than those who did not.
What is important for this study is that the monkeys were given different doses of hormones during the month to imitate the natural hormonal fluctuations of their previous menstrual cycles. Menopausal women who take hormones on the other hand usually receive a constant dose of estrogen with progesterone.
"Monkeys did not have the same cognitive benefits when they took it in the same dose every day," says Hara. , which is now in the Alzheimer's Drug Detection Foundation. "This could have consequences for the best way to treat postmenopausal women in the future."
Considering the genetic similarities of primates to humans, it is not surprising that they are much sought after by scientists and are reported for a record 76,000 animals in American studies in 2017. At the same time the low two-stranded striped fish, which shares 70% of its genes with humans, is also gaining popularity.
The world is aware that these fish are amazing genetic patterns for humans. I tell people to go fishing, "says environmental biologist Keith Tearney of the University of Alberta in Canada. Although they have a short life of only three years, they become adults within three months and allow scientists to see the effect of various interventions quickly.
Zephyr also has the same muscle loss in old age that people do. Tierney begins a study that nourishes various diets (a vegetable mix, a mix of animal muscle protein and another with this modern new source of protein: crickets) to see how it affects their athletic characteristics and muscle tone as they become older. "We put them in special zebra treadmills to see how fast they move and how much oxygen they use," says Tierney. "The goal is to learn how to keep our human aging population healthy on cheaper green proteins that are easier for the environment."
Despite the wisdom that animals can offer to humans, some experts warn that they do not do too many parallels, especially since many clinical studies of promising medicines in animals fail in man. "If we study the DNA of aging in a mouse, it will not give us a predictable value for what is happening in humans," says Ray Greg, an anesthesiologist near Santa Barbara, California, and co-author of Animal Models in the Light of Evolution "There are too many differences between the species that have been fine-tuned through evolution. We must turn from the use of animals directly to the study of people. "
Other experts, like Stanford epidemiologist John Ioannis, say that animal studies are needed to test the safety and effectiveness of interventions before testing them on humans. "The information we can get from animals before we jump to people is invaluable," he says.
But there are too many variables, including the complexity of diseases and animal species, to understand which studies will be useful. A review in the BMJ's medical journal documents the intervention of animals that has the opposite effect on humans. For example, a stroke medication has helped the animals but has aggravated the condition of humans.
For researcher Julie Matheson of the National Institute of Aging, the animals will not give us all the answers about the age of humans, but they can direct the scientists. in the right direction . Mattison, who studies the effects of intermittent starvation on the health and longevity of humans, is developing a study of rhesus monkeys to test whether feeding for few hours over several days will improve brain function, immunity and metabolism  "People's research is often more expensive and complex because you do not have the same controls and follow-up," she says. In other words, monkeys do not live in a world of processed foods, invitations to happy hours, and fries.
"The animal model enables us to understand the mechanisms for which we can have these benefits," says Mattison. , "It's easy to tell people to lose calories in a few days. But they need to understand what's going on in their bodies, and why such nutritional intervention can slow down age-related illnesses and help them live longer in good health. "