Jeff Bezos is on a mission to defeat aging. He comes from recruited Hal Barron from GlaxoSmithKline to help lead Altos Labs, the ambitious new anti-aging company with billions in investment. So what does science really say about this? Could we beat aging?
Aging is not just a change in the way we feel or look, aging happens at the cellular level. In a culture dish in the laboratory, adult skin cells divide about 50 times before stopping. But a newborn’s skin cells can divide 80 or 90 times. And on the other hand, the cells of an old person divide only around twenty times.
Aging is also evident in our genes. Our genetic material is changed over time – chemicals can be attached that alter which genes are turned on or off. These are called epigenetic changes, and they accumulate with age. Another type of change takes place at the ends of the DNA of our cells. Repeating segments of DNA called telomeres act like the plastic tip of a shoelace, preventing twisted coils of genetic material from fraying at the ends or tying themselves together. But these telomeres get shorter every time a cell divides. We don’t know if short telomeres are just a mark of aging, like gray hair, or part of the process by which cells age.
Cells, chromosomes and telomeres
To stay alive and keep dividing, immune cells stop shortening their telomeres when they multiply, just like cancer cells. This is likely a contributing factor to their apparent immortality. Drugs that stop telomerase from working also show promise against cancer (although cancer cells can develop resistance).
Since aging has such a profound effect on our cells and genes – the effects mentioned here are just a few examples – a much larger question arises: why is this happening? Why do we age?
Aging was once thought to occur for the continued evolution of species. In other words, the evolution of a species requires a renewal of individuals. However, a problem with this idea is that most life on Earth never reaches old age. Most animals are killed by predators, disease, weather, or starvation. Thus, a built-in limit to an animal’s lifespan may not be evolutionarily important.
Another view is that aging is just a side effect of damage that accumulates over time that is caused by metabolism or exposure to ultraviolet light from the sun. We know that genes are damaged with age, but there is no evidence that this directly causes aging. Another possibility is that aging may have evolved as a defense against cancer. Since cells accumulate genetic damage over time, they may have developed a process to not linger too long in the body, in case that damage eventually turns a cell into cancer.
As we age, certain cells in the body enter a state called senescence, in which a cell stays alive but stops dividing. Senescent cells accumulate in the body throughout life – particularly in the skin, liver, lungs and spleen – and have both beneficial and harmful effects.
They are beneficial because they secrete chemicals that help repair damaged tissue, but over a long period of time, as the number of senescent cells increases, they can disrupt the normal structure of organs and tissues. These cells could be an underlying cause of many of the problems we associate with aging. Mice in which senescent cells were cleared were profoundly retarded to show signs of aging.
We can describe much of what happens during aging at the level of what physically happens to our genes, cells and organs. But the fundamental question of why we age remains open. In all likelihood, there is more than one correct answer.
Of course, no one knows if Bezos’ company can succeed in helping to extend the human lifespan. But what is clear is that in studying aging, exciting new discoveries are inevitable. Never listen to someone who says the big questions have already been answered. As I recently detailed in a book on new technologies and the human body, The secret bodyI am convinced that spectacular breakthroughs will profoundly change the human experience in the century to come.