Have you talked to other scientists about this study, and what do they make of it?

Yeah, so I spoke to an endocrinologist called Channa Jayasena, who's at Imperial College.

You know, he does a lot of work on testosterone.

And he said although there are some possible confounders, things like, you know, significant changes in the way things are measured maybe having a bit of an effect on the readings that you get, he said that this was actually really quite convincing that something has happened, that testosterone levels have declined.

And the fact that it's looking at this long time period, and each of the studies kind of consistently find the same pattern, he felt that that was quite convincing.

I have since spoken to another US scientist who specializes in testosterone who was more skeptical, who said they haven't accounted for possible differences in age between the cohorts.

And it's worth saying that this work is from the same team as the group who did a very influential paper on declining sperm counts globally in 2017.

Why is testosterone falling? Do the authors themselves have any theories as to what's going on?

Before we start, I wondered if you had a favourite story from last year.

So I was thinking about this and I think it was a really good year for science.

There were some great James Webb stories and it was an exciting trial for Huntington's disease.

But I think actually my personal favourite was a story about the quest for a universal anti-venom for snake bites.

And it came about through essentially a snake hobbyist, a snake collector.

And he had started collecting venomous snakes recently.

had a few run-ins with the snakes, been bitten.

So what progress have we seen up to this point that's suggesting this year could be an exciting one for fusion?