The findings show the effect of age on the skin - not necessarily increasing risk of cancer.
They come from a scientific study aimed at tracking the development of skin cancer.
Researchers studied samples from four patients aged between 55 and 73 after they underwent surgery to remove excess skin on the eyelids.
Researchers said "almost certainly" none of the mutated cells would have developed into skin cancer.
The researcher was conducted at the Wellcome Trust Sanger Institute, Cambridge, UK, and reported in Science.
Researchers found more than 100 cancer-linked mutations per square centimetre of skin. From 234 biopsies, the researchers found 3,760 mutations.
Researcher Dr Iñigo Martincorena said: “The burden of mutations observed is high but almost certainly none of these clones would have developed into skin cancer.
“Because skin cancers are so common in the population, it makes sense that individuals would carry a large number of mutations. What we are seeing here are the hidden depths of the iceberg, not just the relatively small number that break through the surface waters to become cancer.”
Fellow researcher Dr Phil Jones added: “These kinds of mutations accumulate over time – whenever our skin is exposed to sunlight, we are at risk of adding to them.
“Throughout our lives we need to protect our skin by using sun-block lotions, staying away from midday sun and covering exposed skin wherever possible. These precautions are important at any stage of life but particularly in children, who are busy growing new skin, and older people, who have already built up an array of mutations.”
Martincorena I, et al. High burden and pervasive positive selection of somatic mutations in normal human skin. Science 21 May 2015 [abstract]
"Time is muscle," experts said- applying a comment normally used for an acute heart attack.
The condition is caused by a worsening of chronic heart failure or the sudden onset of shortness of breath and raised blood pressure.
The recommendations, published in the European Heart Journal, have been agreed by the Heart Failure Association of the European Society of Cardiology, the European Society for Emergency Medicine and the Society for Academic Emergency Medicine in the USA.
Developer Professor Alexandre Mebazaa said: “This is the first guidance to insist that acute heart failure is like acute coronary syndrome in that it needs urgent diagnosis and appropriate treatment.
“By introducing the time to therapy concept together with new medications for acute heart failure we hope to achieve the reductions in mortality and morbidity seen with acute coronary syndrome.”
He add: “Many patients die from AHF during the first hospitalisation. Around 30-40% of discharged patients are back in hospital within 30 days. This is contrast to most conditions, where patients are treated and do not return.
"We need to do everything we can to avoid readmissions in the first 30 days.”
Fellow developer Professor Abdelouahab Bellou said: “If we treat patients with AHF earlier we can expect a decrease in mortality and morbidity.
"Failure to treat quickly aggravates underlying chronic heart failure and can induce complications including cardiogenic shock and acute respiratory distress. Patients may need to be intubated which can increase their risk of mortality.”
Recommendations on pre-hospital and hospital management of acute heart failure: a consensus paper from the Heart Failure Association of the European Society of Cardiology, the European Society of Emergency Medicine and the Society of Academic Emergency Medicine. European Heart Journal 22 May 2015; doi:10.1093/eurheartj/ehv066
GP trainers should be better funded and the profession made more attractive for students, the conference of local medical committees heard.
Student unwillingness to take on general practice has been seen as one of the key factors in the growing crisis in primary care.
The government set a target to train 50% of doctors as GPs but numbers have fallen well short.
A recently qualified GP Dr Pooja Arora told the conference it was "no secret" that the perception of general practice among students needs improving.
She said: "I don’t think any trainees are worried about working hard - more about getting training meeting their educational needs."
The scheme is intended to put an end to GP catchment areas, allowing patients to register at practices they choose.
It is being tested in a number of cities in England.
But GP leaders said yesterday they remain opposed to it - partly because of the difficulty of providing urgent GP care to patients registered miles from a practice. It can also cause doctors difficulty in getting patients access to secondary care, they said.
The British Medical Association's conference of local medical committees yesterday voted for the project to be scrapped.
The deputy chair of the BMA's GP committee, Dr Richard Vautrey, said it advised practices not to take part in the scheme.
He said: “We remain concerned that this scheme fragments patient care which could risk their safety, and no effective arrangements have been put in place for patients to be able to access local GP services if ill at home under the out of area scheme.
“We have repeatedly raised concerns with NHS England that they have failed to provide a robust home visiting service for out-of-area patients as GPs from across England have told the BMA that these arrangements are either not clear, or are not working in the way in which they were intended.
“It remains our view that practices should only register out of area patients after area teams have assured them that arrangements for urgent GP services including home visits are in place for individual patients at their place of residence."