Sex with Year 13

Happy New Year! I hope you all had a super winter break and have started the Spring term energised and invigorated.

I’ve come back to a department where half the tubes of fruit flies in our breeding experiments have been desiccated into little wispy fragments after being left on the light bank. I also tracked down the missing department hamster – trapped in a cupboard, she was considerably thinner, drier, flatter and deader than when I last saw her. I am surprised by how upset I am – she was a particularly lovely and beautiful hamster.

Anyway, I thought I’d kick off 2016 with an idea I had from the superb Life Ascending by the incomparable Nick Lane. It’s a way of introducing a topic that aims to be memorable by challenging students to look at something in a completely different light. It’s also a desperate ploy to try and increase my WordPress stats, for that topic is Sex (sorry, lonely person in Russia, you’re going to be disappointed again).

Now, for most teenagers, indeed, for most people, the word Sex means something very specific. I remember a student who was distinctly sceptical at the notion that plants were actually living things, but absolutely categorically refused to believe that plants have sex. No, no, absolutely not. For her, sex meant something very specific that was certainly an activity that plants could not possibly partake in. Nothing could shake her belief in this. I like to think she would have found this lesson interesting….

So without mentioning the word Sex, I start with this interactive powerpoint.

Introduction to Sex

Go on, open it up and have a go. Actually, it’s not very interactive. All they do is choose a colour, you click on the box and it reveals a picture. Click on the picture and it takes you back to the first slide (apart from two, which are hyperlinked to video clips). As you explore the pictures and videos, just ask the class, do each of these examples make the world a richer place?

There are some surprising responses. One class was absolutely spellbound by the Marriage of Figaro clip and my frenetic attempt to describe the plot (note that it doesn’t have to be Marriage of Figaro – London Burning by the Clash would be just as good, or even, god forbid, One Direction….) but claimed to be completely disinterested in fashion. Another class agreed that flowers were nice but didn’t think much of butterflies.

But everyone loves the Birds of Paradise, David Attenborough, dancing and Van Gogh. Phew!

So then the question is, what do they all have in common?

The answer, of course, is Sex. And it’s fun to discuss all the various reasons. But the point I hope they take away is Nick Lane’s point, that an Earth where Sex had not evolved would be a dull, grey, monotonous kind of place. Whatever Sex might mean for them on a personal basis, it has more profound implications than our human-centric view of it.

Not sure they were entirely convinced but it was different enough for me to give it another go next year (if nothing else, it ticks the unpredictable/variety boxes of lesson planning!).

I then like to approach the topic from the theoretical challenge of why on earth Sex ever evolved in the first place. There’s a wonderful 10 minute sequence at the start of Frozen Planet where a male polar bear looks for a mate. Not only does it look amazing, but it graphically illustrates the problems with Sex as a method of reproduction, starting with the camera panning back to reveal the poor solitary male in a vast empty wilderness. All that time and energy looking for a mate! Surely it’s much easier and simpler and quicker to bud a new polar bear from your shoulder….

By the end of the clip, the male is absolutely battered, limping, shattered, covered in blood, from fending off so many rivals. It’s real Iorek Byrnison/Iofur Raknison stuff. Clearly, this is a seriously risky business! It just doesn’t make any sense. I shower them with questions. Why else is it risky? Childbirth. Being eaten by your mate (some species). STDs. How else is it costly? Display. Song. Growing special “come hither” feathers. I tell them about the male skylarks who fly vertically upwards while singing their hearts out. It might be beautiful, but he’s only doing in a desperate attempt to have Sex.

And why else is it just plain daft, when you could just clone yourself?

With a little prompting, they see the idiocy of diluting your perfectly good genome with some dodgy genes that you have no idea where they’ve been are probably harbouring some potentially lethal alleles. And why dilute it by 50% anyway? Don’t you want your children to be 100% related to you? Sex? Utter madness!

They tentatively point out that Sex generates variation.

Aha. That’s true, so it must convey some pretty major benefits to outweigh the negatives

So then I tell the story of the New Zealand snails. They really like this, as they like most stories (never underestimate the power of stories – it’s how they remember). It’s important to use the Powerpoint as a prompt for questions.

New Zealand Snails and sex

Where’s this? They usually get New Zealand, though other answers are generally entertaining.

Where’s this? Big river estuary. Yes, it’s the Thames. Deptford. I once had a girlfriend in Deptford. Had to get the 107 bus from Euston to visit her. But I digress.

150 years ago, how would you get from London to New Zealand?

Why would you want to?

I talk about Eric Newby’s The Last Grain Race and his hilarious recruitment on to a Scandanavian wheat clipper (worth reading just for the “oop! Ooop!” bit).

Which way would you go? Why would it be a bad idea to hug the coast of Africa? Tales of the doldrums and yellow fever and the trade winds.

And so, you reach New Zealand with your sheep and off load them. But what do you need to do before you can go home? Yes, this is before you could have filled your hold with crates of Marlborough Sauvignon Blanc, so you need some ballast! Take on some rocks from the fresh water estuary…

…. oh, look, there’s a stowaway…

Back to England! Which way? Yes, don’t fight those prevailing winds in the great Southern Ocean.

And back in Deptford, ready to take on more sheep, what do you do? Yep, unload the ballast and off hop the snails. Who happily go forth and multiply in this exciting new land…

And finally you can get to the whole point of this long winded story!

Because snails have the option. Asexual or Sexual reproduction. They can do both. And in New Zealand, they have Sex. And in England, they don’t.


You’re all bright enough to figure this out for yourselves, if you don’t already know, so with the general advice that if you come back as a freshwater snail, make sure you’re in New Zealand, that’s enough for this week.



Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s