Parts of the body regenerate in days and others in years. This means that our bodies are younger than our birth certificate, according to Swedish scientists who have used carbon dating to make their findings.
Our bodies are weeks, years and even decades younger than our chronological age because cells and tissue regenerate, they say in a report in the New Scientist magazine.
The technique uses levels of a radioactive form of carbon called carbon-14 to gauge the age of objects.
Usually accurate only to between 30 and 100 years, carbon-14 dating has been refined by researchers at Sweden’s prestigious Karolinska Institute to be able to pinpoint the age of parts of the human body.
The team compared levels of the element in the human body with those in the atmosphere when nuclear weapons testing was at its height 50 years ago.
Factoring the length of time it takes carbon-14 to decay allowed them to accurately date various body parts.
They found the hardest-working cells had the shortest life, with some wearing out and being replaced within days.
Eyelashes and eyebrows are renewed in eight weeks, tastebuds every 10 days.
The lining of the gut has a lifespan of just five days, but muscles are much older – those of someone in their late 30s have an average of 15.1 years.
Professor Jonas Fisen has also been able to age some brain cells, revealing that those in the cerebellum, which co-ordinates movement, are about three years younger than we are.
Anti-ageing specialist Joe Kosterich said as we got older, our ability to regenerate became less efficient.
Dr Kosterich said: “It’s like taking a copy of a copy. Enzymes that work on our DNA become less effective as we age so you start to replace pristine healthy cells with ones not quite as good. The whole ageing process is very likely linked to the breakdown of restorative and repairing mechanisms in the body.”
The Swedish research suggests – if averaged out, someone in their late 30s would have a body just 15 1/2 years old.
They hope the research will help shed light on degenerative conditions linked to cell death, including Parkinson’s and Alzheimer’s.
Dr Kosterich said in the meantime, the best defence against ageing and to promote healthy cell regeneration was exercise and anti-oxidants.
“Although exercise actually causes the body to regenerate and repair more, it keeps our regenerative system ticking over so you are making a better copy of yourself, so to speak,” he said.
Dr Kosterich said the enzymes which assisted the regeneration of tissue and cells were adversely affected by toxins and anti-oxidants could help promote healthy tissue repair.
“In this case, it’s exercise first, anti-oxidants second, but you also have to live a healthy lifestyle with a good diet and weight maintenance,” he said.
Different body parts age at varying rates.These figures show the average age of the body parts of someone in their late 30s
Cerebellum 2.9 years
Eyelashes 2 months
Tastebuds 10 days
Bones 10 years
Surface of skin 2 weeks
Rib muscles 15.1 years
Gut 15.9 years
Gut lining 5 days
Red blood cells 4 months