Doubtless, modern western medicine will try to take the credit for this. Certainly, it has helped people to live longer, healthier lives. But for the most part, the credit for the coming glut of centenarians lies elsewhere. According to Thomas Perls, the director of the New England Centenarian study at Harvard University, dying at 100 is qualitatively different from dying at 80. In a paper soon to be published in the International Journal of Geriatric Psychiatry, for instance, Dr Perls and his colleagues show that the brains of the very old age more slowly than those of their younger, but more frail companions.
Genes are the prime suspects.
In a recent paper in The Lancet, Masashi Tanaka and his colleagues at the Gifu International Institute of Biotechnology, in Japan, reported that they had found a gene which is carried by a majority of Japanese centenarians, but by less than half of the rest of the Japanese population, suggesting that it could play an important role in a healthy old age. The gene in question is harboured in pieces of cellular machinery known as mitochondria. Many diseases of old age, such as Alzheimer s, are now thought to be linked to changes in mitochondrial genes. Dr Perls is looking for other examples of genes that might be important for longevity. To do so, he is studying as many pairs of venerable siblings as possible, in the hope that the genes they have in common hold the secret of their advanced years.