One of the biggest scientific quests since long before the birth of medicine has been immortality and the extension of one's lifespan. With a range of theories, findings and studies underway on aging, researchers are inching close to finding important answers in our very own DNA — specifically, the portion of our DNA where key changes take place during the aging process: telomeres.

Telomeres are long, repetitive sequences of DNA that are found at the tips of each and every chromosome (a compact DNA strand) in cells. Every time DNA replicates (like when cells divide), telomeres get progressively shorter since replication isn't a 100 percent end-to-end process. These structures act like buffers — protecting the DNA in these compact chromosome structures.

The shorter one's telomeres are in length, the more "worn out" the cell is — this being the most fundamental cause of aging in animals: telomeres get shorter and shorter with age. Much of the research around aging and longevity today focuses on keeping telomeres intact, healthy and strong for as long as possible.

An illustration of the human X chromosome in fluid with yellow DNA strands inside. Image: Getty

In new research that builds on past findings, scientists have found that a certain kind of stem cell — induced pluripotent stem cells (iPS) and embryonic stem cells — have telomeres twice as long as in regular cells. These iPS cells, when left to divide in a laboratory petri dish, produces more identical cells with extra-long telomeres.

Unlike aging studies thus far, where researchers have used modifications to DNA to target aging, scientists used the natural feature of these pairs of cells to maintain extra-long telomeres.

Researchers in the new study used embryonic cells with these doubly long telomeres to breed chimeric mice without the use of any genetic modifications at all.

"This finding supports the idea that, when it comes to determining longevity, genes are not the only thing to consider," Maria Blasco, molecular biologist from the Spanish National Cancer Research Centre (CNIO), said in a statement. "There is a margin for extending life without altering the genes."

And their experiment worked — the long-telomere mice survived 24 percent longer than otherwise, were slimmer, and less likely to develop cancer. Various indicators of metabolic aging turned out to be lower too, researchers reported.

While it is unlikely that a similar test will be carried out in humans anytime soon, the results do show a strong link between the length of telomeres and an animal's lifespan. The study's findings could open up new methods for taking advantage of the link.

"Together, these findings demonstrate that longer telomeres than normal show beneficial effects in mice, delaying metabolic ageing and cancer, and resulting in longer lifespans," conclude the researchers in their published paper.

The research has been published in Nature Communications.