By 4% which may as well be experimental error, right? The mice could have very well just lived longer due to increased interest/handling/measurement of their welfare.
This seems insignificant when compared with other selector genes such as H63D and C282Y, which could potentially double or halve subjects life span depending on environmental factors.
I would hope that they controlled for such systematic effects in the experiment (did not read the paper) by mixing individuals from both groups (my guess would be that they do not look different). I guess they should have also modified some other random gene in the control. Did they actually?
However, I find it very interesting that all those important details seem somewhere hidden in the paper. Also I guess if you consider a 10x increase between the species and then end up with 4% this sound really far less spectacular.
Doubling lifespan is definitely a bigger impact than 4%, but let's explore what the hypothetical "perfect application" of this study to a human life.
A fairly average lifespan is 80 years, so a 4% increase would be about 3.2 years. If I were offered a "wonder drug" that would give me 1,168 more days with a loved one, I would take it.
Obviously that is not how science like this works, but stacking small victories over time is a way to achieve "significant" impact.
Hm, would you go through the process of GM your (otherwise naturally conceived) kid on the chance that their lifespan would increase by 4%? For me personally, OK, 10% ... maybe, 20% definitely.
But what stigma and complications/risks could they live with for a 4% increase in lifespan? What if they find out in 30 years time that their GM means that they can't have kids with their partner or something because there is some biological incompatibility that wasn't anticipated and it just miscarriages. What if some country is Xenophobic to the idea and won't grant them residency or a passport because they are GM, or they are eventually targeted by some kind of anti-GM hate group? Would that 4% be worth it? Like everything it's a risk-reward value prop.
Biologic incompatibility isn't as much of a concern. At least not with the modification in the article. Our genes encode a wide variety of proteins and enzymes that differ from person to person. Even people with significantly debilitating mutations havent had trouble conceiving. Even people with extra x or y chromosones do not have to worry about the matter. Though some men do have strange mutations like only being able to conceive girls with their partner.
I know there's the replication crisis and everything, but let's not be over cynical - I don't think Nature would publish a study that didn't use basic statistics and didn't have a control group for its experiment?
Typically Nature or high impact journals are specifically more likely to publish irreproducible studies.
It's very similar to the well established fact that students with good grades are the most likely to cheat.
If you want to look for solid research, don't look to Nature, look to the so called "mid tier" journals.
Also, similar observations are true for research groups. Research from ivy-league universities follows similar principles as above.
This seems insignificant when compared with other selector genes such as H63D and C282Y, which could potentially double or halve subjects life span depending on environmental factors.