And the Hello and welcome to the naked scientist with me Chris Smith and also with

Katani. This week the chemicals that run our sex lives hormones are the driving force behind

reproduction and are what makes us able and willing to go about making babies.

We follow some of these hormones to hear how they have an influence from birth to death,

and also some unexpected consequences, like perhaps the recent credit crunch.

Plus, in the news, what Phili has revealed about the comet that it touched down on, how the bugs in your

gut might be making you moody and the key to making your hamster happy.

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In November last year, scientists from the European Space Agency achieved the first ever

landing of a probe on a comet when Fili touched down on the surface of 67P Chiriamov-Juracimenko.

You love saying so, Chris.

This week the journal science are publishing seven key papers

detailing the discoveries made by filli on the surface of this comet.

It's more than 4.5 billion years old and it's assembled from the same stuff that spawned our planet.

Earlier this week I spoke to two of the mission scientists about the results.

Up first, Andrew Coates from UCL's Mulard's Base Science Laboratory.

So one of these papers is actually talking about the strength of the comet and it was a hard surface, but underneath a much softer surface,

which seems to be stuff which has come out in the cometry eruptions

which are going on all the time to produce the cometry comer and the tail and everything.

Right, so just sort of summarising that then, what we've learned is that the surface is extremely

hard like an iced cake and it's a softer sort of morangy, sodgier stuff inside?

Yeah, well, yes, it's softer inside, but on the surface, you know, it's very hard.

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