I am pathetically fond of April Fool’s Day. My proudest moment was faking labour pains in the Hampton Court Maze. Mr Science Notebook was not especially pleased, but at least I owned up before he dialled the final “9”.

It is also a good day for running all those weird science stories that defy belief, such as the revelation that South Korea expects to issue a robot ethics charter this month. A team of technologists, futurists and a science-fiction writer began drafting the charter last year, according to New Scientist. It is aimed mostly at those building robots, and deals with mundane matters: how to stop robots being used for illegal purposes (I keep imagining Kryten from Red Dwarf trying to board a flight with a stash of cocaine), how to protect data acquired by robots and how to make every machine traceable.

But the charter will also contain rules forbidding robots from causing harm to human beings. The rules are expected to echo the Three Laws of Robotics crafted by Isaac Asimov. These are: (1) A robot may not injure a human or, through inaction, allow a human to come to harm; (2) A robot must obey orders given by a human unless these conflict with the first law; (3) A robot must protect its own existence as long as this does not conflict with the first or second law.

The idea of a robot being able to distinguish between “good” and “bad” is a little farcical. For now, at least, there is no chance of robots gaining so much intelligence that they somehow acquire autonomy. Computer scientists are still struggling to get them to do simple things, such as converse with real people. I learnt recently that the gravest challenge in teaching a robot to play Connect4 was not strategy but getting it to drop the pieces in the appropriate slot.

Anyway, who’s going to be mad enough to trust a robot to make life-or-death decisions? Er, South Korea. It has unveiled robots equipped with machine-guns that it may use to patrol its border with North Korea. The biggest selling point of these £100,000 metal boxes is that they can tell the difference between human beings and trees. Regrettably, it is April 2 and that’s not a joke.

Why are people not uniformly beautiful? If females select the most handsome mates for breeding (sexual selection), then the prettiest individuals should have bonked their way to world domination by now and sexual selection would no longer be possible. Now Professor Marion Petrie and Dr Gilbert Roberts, of Newcastle University, have figured a way round the “lek paradox” (a lek is a congregation of courting males; peacocks form leks to show off their tails). They report in Heredity that a narrowing of genetic diversity due to sexual selection can be widened again by random DNA mutations. Earlier work has shown that attractive people may have more mutations, some of which will be beneficial and result in fitter, if plainer, offspring.

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