Thirty micrometres a minute: scientists discover the speed of death

By studying frogs’ eggs, researchers have measured the rate at which cells kill themselves off for an organism’s greater good

Computer illustration of the destruction of a human cell. Photograph: Kateryna Kon/Getty Images/Science Photo Library RF

Name: The speed of death.

Age: Not sure that is entirely relevant.

Appearance: Cellular.

You’re talking in riddles. I’m bracing myself for some seriously hard science.

Stop beating about the bush and get on with it. OK, here goes. Two Stanford University systems biologists, Xianrui Cheng and James Ferrell, have discovered the speed at which cells die.

What is a systems biologist? A biologist who is good at maths, but you are missing the bigger picture.

What is the bigger picture? If we know the speed at which cells die and, more to the point, the way in which they die, we can do amazing things.

Like what? Oh, you know, curing cancer by encouraging cancerous cells to kill themselves, and stopping cells from dying in patients at risk of Alzheimer’s disease.

So what is the speed of death? According to Cheng and Ferrell, writing in the magazine Science, it is 30 micrometres a minute.

I’m not familiar with the micrometre. That is because you are not a systems biologist. It is often abbreviated to micron, and is equal to 1×10-6 of a metre, one-millionth of a metre or one-thousandth of a millimetre.

So the speed of death is 30-thousandths of a millimetre a minute?Apparently so. The New Scientist, in its headline on the findings, helpfully expresses it at two millimetres an hour.

And what is actually dying at that rate? Cells. By studying frogs’ eggs, Cheng and Ferrell have measured the rate of apoptosis, which is best understood as a form of cell suicide or “programmed cell death”, by which cells kill themselves off for the organism’s greater good. Sometimes the cell senses it is time to quit; other times neighbouring cells give it a nudge via trigger waves. Cheng and Ferrell have measured the speed of those trigger waves.

But these cell deaths are good? Mostly, yes. The average human loses more than 50bn cells a day and gets along fine without them. But sometimes the cells get confused, and ones you need die off or ones you don’t want hang around, so the more we understand the process of cellular death, the more effective biomedical interventions will be.

Not to be confused with: Speed of Death, a track from the album Born to Hate by the New Zealand punk band the Cavemen.

Do say: “Who says we can’t get our heads around cutting-edge science?”

Don’t say: “I think I need a lie-down.”

Leave a Comment