Wednesday, November 28, 2012

Immortaly Tomfoolery

Their is a saying among scientists that the more you know about the scientific subject a journalist is writing about, the less of what he writes makes any sense. There is a long new article in the New York Times magazine about a hydrozoan jellyfish, Turritopsis dohrnii, which the author claims holds the key to immortality. As someone who happens to work on hydrozoans, and on aging, I can assure you that not a bit of it makes any sense. The title, "Can a Jellyfish Unlock the Secret of Immortality?" should be a dead giveaway that this is magical thinking with a whitewash of pseudoscience. The argument behind the article, striped of its misunderstandings and untruths,  goes something like this:

1. There is this jellyfish that can develop back from the medusa phase, which we normally think of as the adult, to the polpy phase, which we normally think of as the juvenile. It can then develop into the medusa phase again.
2. We are going to assume that this is the only know case of an organism that does not show a human-like pattern of aging.
3. We are going to assume that this non-human like pattern is equivalent to immortality.
4. We are going to assume that if we understood the mechanisms behind this assumed immortality, we would know how to make humans immortal.
5. We would know by now what makes them immortal except that we are going to assume that the one researcher I talked to extensively for the article who studies the species is the only one doing so.
6. We are going to assume that this one researcher is unfunded and working alone not because he is considered a crackpot, but because the rest of science is just too blind and lazy to see the importance of this man and his work.
7. We are going to assume that when he has learned a little bit more, we will achieve immortality.

I do not recommend that you read it, and mention it only because I have been asked about it, and because I would like to speak briefly about the word immortality. Immortality is defined as immunity from death. Immortal beings cannot be killed. Turritopsis dohrnii can very easily be killed. Put one out of water for a few minutes, feed it to a predatory snail, heat it, freeze it, slice, dice or frappe it, and it will be dead. Ergo not immortal. However the journalists are not to blame for the misuse of the word. A very good recent paper in PNAS from a very good careful research group is titled, "FoxO is a critical regulator of stem cell maintenance in immortal Hydra." They use the word immortal as many people in bio-gerontology do, to mean that the risk of death does not increase with age. My general impression is that using the word in this way is misleading, but that it is a lot flashier than 'nonsenescing' and therefore widely used.


GML said...

Perhaps organisms cannot avoid senescence if they reach a plateau and stay on it; they may need either to keep on growing larger or to regress back to their beginnings or to change to a very different form. Very strange. GML

dan levitis said...

The thing to keep in mind is that not one of the assumptions I listed is true. These "immortal jellyfish" actually do senesce. The medusa gradually degrades and eventually dies. But sometimes before it degrades too far part of it can develop back into a polyp. The assumption that no other things don't senesce is also not true. Hydra polyps stay as polyps indefinitely without showing any sign of aging. They reach a plateau and stay there.