The tree
Eight things that would have to be dealt with
The published science groups ageing into twelve "hallmarks": twelve kinds of damage and failure that build up in a body over a lifetime. This site groups them into seven kinds of damage that repair would have to address, and adds an eighth branch for the tools that would show whether any repair worked. Every treatment and tool on the tree sits under one of these; the year on the home page is computed from all eight.
- 1 of 85 treatments and toolsWorn-out cellsCells that have stopped dividing but will not die, and sit in the tissue giving off signals that inflame their neighbours. They build up with age; clearing them makes old mice healthier and longer-lived.Nothing in the clinic yet . Handled, in the middle run, by 2043
- 2 of 84 treatments and toolsDamaged DNAMutations that accumulate in a cell's DNA over a lifetime, and the shortening of the protective caps on the ends of chromosomes each time a cell divides.Nothing in the clinic yet . Handled, in the middle run, by 2040
- 3 of 85 treatments and toolsThe cell's settingsThe chemical marks that tell a cell which of its genes to read, which drift with age so that cells slowly forget what they are. Resetting them part of the way has reversed signs of age in animals.Nothing in the clinic yet . Handled, in the middle run, by 2044
- 4 of 85 treatments and toolsBroken proteins and wasteMisfolded proteins, the failure of the cell's recycling of its own worn parts, and the waste and cross-links between proteins that build up inside and between cells.2 treatments in the clinic . Handled, in the middle run, by 2023
- 5 of 88 treatments and toolsEnergy and fuel sensingThe cell's power plants, which fail with age, and the pathways that sense how much food is coming in, which run wrong with age and are the target of the drugs most often said to slow ageing.1 treatment in the clinic . Handled, in the middle run, by 2028
- 6 of 87 treatments and toolsReplacing lost cells and partsThe reserve of cells that replace lost tissue runs out with age, tissue goes unreplaced and organs fail. The route around that is to supply the parts: stem cells, organs from gene-edited animals, organs grown outside the body.1 treatment in the clinic . Handled, in the middle run, by 2029
- 7 of 85 treatments and toolsInflammation and the body's messagingLow-grade inflammation that never switches off, the gut's community of microbes going out of balance, and the signals cells send each other through the blood going wrong with age.1 treatment in the clinic . Handled, in the middle run, by 2042
- 8 of 85 treatments and toolsMeasuring ageingThe tools that say whether any of the above worked without waiting decades: biological age clocks read from blood or saliva, blood and imaging markers, and whether a regulator will accept any of them as proof that a treatment slowed ageing.Nothing in the clinic yet . Handled, in the middle run, by 2040
How a branch sets the year
Each branch counts as handled in the year its second treatment or tool reaches the clinic: the rung called "in clinical use", where a regulator somewhere has approved it or a doctor can give it outside a trial. The tree is played out many thousands of times, each time drawing a year for every treatment from its range; in each run the latest handled year across the eight branches, plus a few years for treatments to spread from the clinic to ordinary people, is that run's answer. So the slowest branch sets the year, and the fastest two treatments under a branch set that branch. In the middle run the slowest branch is handled in 2044, and the year at the top is 2058. The rule, with its alternatives, is on how the numbers are worked out.
The five stages
Each treatment sits on one rung of a five-rung ladder, the same ladder the sister site The Upgrade Tree uses, so that the two records can point at each other. It moves up when a public record shows the next thing has happened, and it never moves down: if a drug is later withdrawn, the record says so, but the rung it reached stays.
- Idea only. Proposed or worked on, but not yet shown to work in any living animal.
- Shown in animals. Shown to work in a living animal, in a peer-reviewed report.
- First human. At least one person has had it, with a public record of that result.
- In clinical use. A regulator somewhere has approved it, or it is in routine use in a named clinical setting, so a doctor can give it to a patient outside a trial.
- In wide use. Available to the general public in at least one country without joining a trial, and taken up by many people.
44 treatments and tools on the tree: 5 at idea only, 15 shown in animals, 19 at a first human, 5 in clinical use and 0 in wide use. 1 is a long shot, kept on the tree on purpose with the steps it would take and where today's biology would have to give way.