Ancient DNA explains why some people live to be over 100

Italian centenarians have a higher proportion of DNA inherited from ancient hunter-gatherers compared to the general population, according to a new study that could lead to better understanding of ageing.

Studies have previously shown that "good" genes inherited from one’s ancestors, along with other factors such as the environment and daily habits, help people live longer.

While previous research has shown that Italy has one of the highest concentrations of centenarians in the world, the exact reasons for this remain unclear.

To understand this, scientists analysed the genomes of over 300 centenarians and nearly 700 healthy adults aged around 50.

Researchers then compared the DNA of these individuals with the ancient genomes of four groups that make up modern Italy.

These groups are descendants of Western Hunter-Gatherers, the original inhabitants of Europe after the Ice Age, as well as Anatolian Neolithic farmers, Bronze Age nomadic groups and ancient groups from the Iranian and Caucasus regions.

Scientists found that people who reached the age of 100 tended to have more Western Hunter-Gatherer (WHG) DNA than the average person.

"The present study shows for the first time that the WHG lineage... contributes to longevity in the Italian population,” researchers wrote in the study published in the journal GeroScience.

While the Italians sampled in the study carried a mix of DNA from all four ancient groups, only the WHG genetic material was found linked to longevity.

With every small increase in hunter-gatherer DNA, a person's chances of becoming a centenarian rose by 38 per cent, the study found.

Women were more than twice as likely to reach 100 years of age if they had a higher proportion of this ancient DNA compared to men, according to the research.

"We propose that the variants involved in this trait [longevity] may have been introduced into the Italian gene pool at a very ancient time," scientists wrote.

Researchers suspect these genes were likely favoured during the last Ice Age, when our ancestors had to survive extremely harsh conditions with limited food resources.

Some of these genes, scientists suspect, could be helping improve metabolism to process food more efficiently and protect the body from age-related stress.

“We showed a greater contribution from Western Hunter-Gatherer-related ancestry to Italian centenarians, thus suggesting that this pre-Neolithic genetic component, which has been linked to population shifts occurring within Europe after the Last Glacial Maximum, could be beneficial for longevity today,” researchers wrote.