Immortality Is Impossible, Say Scientists Sutdying the Mathematics of Aging

Original Article

By Peter Hess

While healthcare has dramatically extended our lifespans by preventing certain causes of death, aging still inevitably takes its fatal toll. And, as scientists report in a new Proceedings of the National Academy of Sciences study, that’s not going to change: Whether it’s by cancer or run-of-the-mill cell destruction, aging and death is mathematically inescapable.

In the paper published Monday, Joanna Masel, Ph.D., and Paul Nelson, Ph.D., both of the Department of Ecology and Evolutionary Biology at the University of Arizona, provide mathematical evidence that aging and eventual death must happen, no matter how we intervene in the aging process.

They explain that every cell in the body is tasked with two opposing missions: ensuring its own survival and supporting the organism it’s a part of. Masel and Nelson reason that this endless push and pull between those missions means that aging is unstoppable.

“If you have [no competition] or too little, then damaged cells accumulate and you get senescence,” Masel tells Inverse. “And if you have more than zero, then you get cancer. Either way, you get decreasing vitality with age.”

The team came to this conclusion by creating a mathematical model of cell competition within an organism. Cells in a human body, they explain, face a unique set of forces under the dynamic of competition: On one hand, cells need to work together for the body to function properly. But on the other hand, those cells must compete with each other for survival, and natural selection among those cells means that competition allows only the fittest cells to survive. This competition, the authors explain, results in cancer as the cells that inevitably find ways to game the system are the ones that end up growing uncontrollably.

When a human ages normally, the survival of any individual cell is sacrificed in the name of the organism’s health. In other words, a certain portion of each cell’s output is devoted to collective health instead of individual health. Ultimately, the triumph of cooperation over competition means that bodies accumulate dead or dying cells in a way that eventually leads to what we know as aging.

Natural selection is a process that’s more commonly liked with the genetic evolution of a population of individuals than of cells, but previous research has shown it plays a role in aging too as the cells in your body need to survive and work together in order for a person to live. Nelson, a postdoc in Masel’s lab, says the new research makes an even stronger statement about how the process of natural selection affects human aging.

“Even if selection were perfect, we would still get aging because the cells in our body are evolving all the time,” says Nelson.

The team came to this conclusion by creating a mathematical model of cell competition within an organism. Cells in a human body, they explain, face a unique set of forces under the dynamic of competition: On one hand, cells need to work together for the body to function properly. But on the other hand, those cells must compete with each other for survival, and natural selection among those cells means that competition allows only the fittest cells to survive. This competition, the authors explain, results in cancer as the cells that inevitably find ways to game the system are the ones that end up growing uncontrollably.

When a human ages normally, the survival of any individual cell is sacrificed in the name of the organism’s health. In other words, a certain portion of each cell’s output is devoted to collective health instead of individual health. Ultimately, the triumph of cooperation over competition means that bodies accumulate dead or dying cells in a way that eventually leads to what we know as aging.

Natural selection is a process that’s more commonly liked with the genetic evolution of a population of individuals than of cells, but previous research has shown it plays a role in aging too as the cells in your body need to survive and work together in order for a person to live. Nelson, a postdoc in Masel’s lab, says the new research makes an even stronger statement about how the process of natural selection affects human aging.

“Even if selection were perfect, we would still get aging because the cells in our body are evolving all the time,” says Nelson.