Wednesday, 8 January, 2014


Many of the posts on my ‘Why Can’t I Have Wings?’ post remind me of this letter.


Man controls new prosthetic leg using leg muscles

Thursday, 3 October, 2013

Though reported as ‘man controls prosthetic leg using thought’, the man is controlling the prosthetic leg using his thigh muscles, which he is controlling using the nerves that used to go to his lower leg and foot (but were surgically re-routed to the thigh). The prosthesis detects the electrical activity in the muscles, rather than the nerves themselves.

So it goes like this:

brain → spinal cord → motor nerve → thigh muscle → EMG in prosthetic limb → movement

Not even interfacing with the motor nerves directly, let alone any kind of a brain-computer interface. This is NOT a mind-controlled prosthetic, any more than any other prosthetic.


Mitochondria transplants at risk of rejection

Tuesday, 1 October, 2013

Those mitochondrial transplants (or ‘three parent IVF’ as it is innaccurately called at times) that I’ve blogged about before (here, here and here) might have a few side effects on gene expression. Replacing mitochondria affected by a genetic disease with those from a gene free donor has been compared to replacing faulty batteries in a camera with fresh new ones. But a recent policy opinion piece published in Science (Reinhardt et al 2013) suggest this analogy might not be totally accurate. One of the authors, Edward Morrow, is quoted in New Scientist:

“For a modern camera you’ve not only got to have the right brand of battery, but the right size, shape and voltage. There are all these parameters you have to have right. You can’t just go into a shop and buy any old one.”

As explained in the piece in Science, the mitochondria of some organisms like fruit flies, mice and monkeys has been shown to interact with the genes being expressed in the nucleus, and thus it probably does the same in humans. Non-invasive methods of replacing mitochondria have been used in most of these studies, which involves mating a male mouse of one line with a female mouse of another line, to produce mice with the mitochondrial DNA of line 2. These offspring were then only crossed to line 1, which after a few generations produces mice that mostly have nuclear DNA of line 1 but the mitochondrial DNA (mtDNA) of line 2 (this is sort of similar to if your mother’s mother’s mother was from a totally different ethnicity to the rest of your family). The results of these experiments were that mice with a ‘mismatch’ had reduced exercise capacity (Nagao et al 1998) and reduced learning ability (Roubertoux et al 2003).

Thus, it’s at least theoretically possible these ‘rejection’ side effects might exist in humans too. We just don’t know, it’s a different species and a different method of mitochondria replacement to those studies. This therapy has been tentatively approved by the Human Fertilisation & Embryology Authority in the UK, and the UK government is drafting regulation for the use of this therapy. This paper shouldn’t change that, as any new treatment is likely to have side effects. The question is whether it’s worth it. I agree with how the Science piece concludes:

Assessing the costs and benefits of MR [mitochondrial replacement] treatment requires that prospective patients are as fully informed as possible. The difference across patients in the severity of expected offspring symptoms in the event that MR treatment is not taken will shape the decision of choosing the treatment versus waiting for the outcomes of further research. Some families who are predicted to be, or who have previously conceived offspring that were, severely afflicted by mtDNA diseases are more likely to be prepared to take the risk. Others whose children are expected to suffer less detrimental symptoms, cognition problems or infertility, may wish to wait for further empirical clarification of the risks involved.

This treatment is very promising for severe mitochondrial diseases. For milder conditions, it might not be worth the risk until we know how the mitochondria and the nucleus interact, and can better work out what mitochondria a good donor needs to have for any given patient.



Unfortunately i…

Friday, 27 September, 2013

Unfortunately it’s not at all uncommon for moral and scientific questions to get tangled up in this way. Let me give an example from a different domain—perhaps the most blatant example of all: the question of whether life begins at conception or at birth. That looks like a scientific question, but it really has no scientific content whatsoever. We understand the process of embryonic development in great depth and exquisite detail—attaching the label “life” at some timepoint would not add the slightest iota to our scientific understanding. We all know, of course, what this question is really about: it’s about whether abortion should be permitted. It is really a purely moral question, disguised as a scientific question.

Why do moral questions get disguised as scientific questions? Basically because it is useful as a debating tactic. Arguments about right and wrong often depend on axioms that are not shared by other people, so they tend to degenerate ultimately into hand-waving and shouting. If an argument is about objective truth, though, everybody who knows all the facts ought in principle to get the same answer. I’m not saying that people who argue about the beginning of life do this deliberately or understand what they are doing—obviously they don’t. But the upshot is the same.

William Skaggs (in “How Could We Recognise Pain in an Octopus? Part 2“, Scientific American Blog)

Basically saying that you do need to understand science in order to form a conclusion about the morality of it, but the moral conclusion you form isn’t a scientific conclusion. It’s informed by science, but science can’t answer moral questions for you.


Scaremongering regarding inheritable mitochondrial disease cures

Thursday, 25 October, 2012

Every single time there are new stories about mitochondrial transplants, it gets touted in the media as some new fancy technique. The most ridiculous of these was written by Rob Stein of NPR, titled “Scientists Breach Ethical Taboo by Changing Genes Across Generations“.

Geneticist[sic] reported Wednesday that they had crossed a threshold long considered off-limits: They have made changes in human DNA that can be passed down from one generation to the next.

Unfortunately for this scare-mongering, this threshold was crossed way back in 1998. And nothing seems to have happened as a result. This new research is quite useful, however. It’s just not ethically groundbreaking. Or new. Or even genetic modification. Just a simple mitochondrial transplant.

If you want some realistic news coverage of this story (free of sensationalism), then I suggest trying the journals Nature or Science. Or, first read the Wellcome Trust’s article about the science of what is being done, and THEN read your average news story about this issue.


In bioethics especially

Sunday, 15 July, 2012

In bioethics especially


Some words of wisdom

Tuesday, 24 January, 2012

I’ve written about mitochondrial transplants for human embryos before (especially how it isn’t new, having been first done in 1998), but it still is getting a lot of press as a “three-parent IVF” method. But fortunately the Wellcome Trust has an article to set them all straight on the science of it. I like this part:

1 + 1 + 0.00001 ≠ 3

Also, in an article to The Times the Wellcome Trust’s director, Sir Mark Walport, wrote this very pithy sentence:

 If a child with donated mitochondria can be said to have three parents, then the recipient of a heart transplant could be said to have four.

Damn straight!