A leading molecular biologist and her children are visiting Sydney’s Royal Easter Show, but it’s 2053 now and things are slightly different.
“Will there be chickens at the Easter Show?” asks Emily, the youngest child. “Real ones that lay chocolate eggs?”
“That’s a bit beyond us,” her mother Professor Mary replies. “In the Future Farm, we’ve been concentrating more on genetic engineering for productivity and pet happiness. A lot’s been achieved but, you know, there’s the melting point of chocolate – there are limits.”
“Not to mention the silver paper,” adds Emily’s brother Nathan. “I think most people would want to know there was tinfoil round the egg. But look at this – these facts are amazing.”
“It says here this chicken laid 365 eggs every year for the last five years. And the eggs are huge! Did they cross a chicken with a kiwi or something?”
“No, that sort of crazy work with hybrids or fused embryos makes the headlines but it hasn’t been particularly useful. On the other hand, it has been possible to change the timing of gene output,” his mother replies.
“Think of our three chooks at home. Remember how we used to get an egg a day when they were young. But now they just swan around the garden as pets. Well, our new centre for comparative genomics has identified the genes that are turned off when hens reach middle age – in nature, the hen genes required for egg production are shut down by accumulated methylation and epigenetic silencing as the chooks age.”
“I guess evolution had no use for those genes after the chickens had reproduced so their activity wasn’t maintained during chicken old-age. Now that we understand all the control regions and epigenetics, we’ve just replaced the switches for all those genes and put in switches that stay on. It seems to work,” she adds, smiling.
“And the huge eggs? Was that just through traditional farm breeding, like in the old days?” asks Emily.
“Partly yes, but we also compared different breeds of chicken and many wild birds and found a gene that controls the size of eggs. Doubling the output of that gene is what did it.”
“I know a bit about bird anatomy and my first thought is ‘ouch’,” says Nathan, “I hope those chickens are happy.”
“We think so,” his mum answers. “Agriculture has been a tough business over the years but we try to make perfect pets now – animals that are happy being on the Future Farm.”
“Those puppies look happy – they’re adorable,” squeals Emily.
“Yes, they are pretty much normal puppies, but like the chicks, they will stay young for longer. Over the centuries, domestic breeding selected the wild dogs that were most like puppies, tame, playful, and always watching for guidance. We were able to just push the juvenile genes a bit more and boost their expression. These puppies will stay puppy-like for years. Some breeds are already a bit like that anyway.”
“What about cats, I love cats,” says Emily, “but they’re pretty much all the same – are the cats on the Future Farm all the same?”
“Not really – come and see. Here’s the miniature cat, and the tall cat. The genes controlling the size of dogs are known and changing their expression in cats gave us lots more variation. But have a look at those – the ones in the cubby house at the back of the pen.”
“Why don’t they come out?” asks Emily.
“Well, those are ‘scaredy cats’. They are indoor cats. A lot of people don’t like cats roaming at night, hunting and killing birds, frogs, small marsupials, and possibly spreading diseases like toxoplasmosis.”
“It’s true the damage they do can be a worry. Anyway, an amazing genetic screen was done in mice – by people studying anxiety. It is very interesting – thousands of mice, with different mutations. They just chose the ones that hugged the side of the cage and never ventured out. We don’t know how the gene works, but the same gene was found in cats – ironic really - and if you over-express that gene, you get a cat that likes it indoors. They are sort of agoraphobic, I guess, but they seem happy that way.”
“Those cows look happy. They’re huge though. What type are they? Do they have growth hormones?” Nathan wondered.
“Probably, but mainly they are natural cows. They come from the Kowmung river in the Blue Mountains near Sydney. We didn’t know much about them at first but their genome shows they come from Africa. Apparently they are descended from the cows Arthur Phillip brought over on the First Fleet in 1788. He stopped in Cape Town and picked up a few.”
“That’s wild,” said Nathan. “So you can fill in the history and migrations of animals just by comparing their genomes.”
“I wonder if the puppies would be good cow dogs or sheep dogs? Could you make a cat that herded sheep? I doubt it,” adds Emily laughing. “What about those sheep? They look different.”
“Yes, looks like they have no tails. The mutation that causes dog breeds to lose their tails is known. If you silence the gene in sheep, then bingo, they have no tails. Sheep used to get fly strike from all the dung stuck around their tails – gruesome! Flies lay eggs in sheep’s flesh and the maggots would eat the sheep alive.”
“The old solution, cutting off their tails was preferred but still yuck. In the future, they just won’t have tails, or fly strike,” explains mum.
“What are those sheep eating? It looks like sawdust and they love it,” Emily asks.
“Yep, we took a gene out of termites, one that degrades cellulose, but the real master stroke was to change the taste receptor – they think they are eating molasses. They’re in heaven.”
“Is that why they’ve got, big, err, very plump, backsides?” asks Nathan sensitively.
“Not really. Those are callipyge sheep – hard to believe but callipyge is ancient greek for ‘beautiful buttocks’.”
“More and more sheep bred for meat will be like that soon. The first one was a spontaneous mutant. The haunches were muscular and perfect for lamb rump.”
“But it took forever to work out the genetics – a whole locus full on non-coding and anti-sense RNA, genetic imprinting, short hairpin RNAs, and methylation. I thought it would never be solved but, at the end of the day, it was simple. It all controlled one growth factor. Ramp that up at the right stage in development and all your sheep will be beautiful.”
“Is this really true, are they really called beautiful buttock sheep?” asks Nathan
“Yep, it’s true.”
“Can you do all this with humans?” asks Nathan softly, almost to himself.
“Why do you ask? Are you growing up too fast too, or perhaps too slowly? Should I be thinking about fixing that? Would we want to do all this with humans, any of it?”
“Something for us to think about,” says Emily as they leave the show.