Do you like The Simpsons? In the movie Homer lets his pig Plopp walk the roof while he sings "Can he swing from a web? No, he can not, he's a pig." It’s fun. It’s humor. But how should we react when it comes to "spider-goat", the genetically modified goats that are for real?

The spider pig song

They look like ordinary goats. Unfortunately, they can’t walk on the ceiling or shoot spider webs or any cool stuff like that. They are genetically modified, since in addition to all their usual goat-genes they have a gene from spiders in them.

“One gene to rule them all?” No, not really. When the goats produce milk it comes with an extra protein, a protein from spiders. So much for super-powers. The protein makes spider silk.

Why are there researchers who want to make goats who milk spider silk? Because spider silk is a unique material. It’s flexible, elastic, lightweight yet strong - five times as strong as steel! At the same time, unlike plastic, it can be broken down by ordinary biological degradation. Spider silk does not pollute.

Spider silk
The spider silk protein is in the goats milk. It must be extracted from the milk to be used, and this process is so far not very refined. When spider silk is made artificially it becomes only a tenth as strong as real spider silk, although it contains the same basic protein component. There must be something special about the glands that spiders use to make threads.

Milk shaped us
Today, we humans have figured out many of the mechanisms and processes that govern life as we know it. Our understanding of biology is so great that engineering methods can be used to give organisms something extra. Spider-Goat milk makes spider protein, apart from doing everything else that goats do.

Over long periods of time, humans have bred animals and shaped them without knowing it. We have even been shaped our-selves, by evolution in response to our own cultural hait of keeping live-stock. In Europe, people had cattle in around 15 000 years, but the gene needed to be able to drink milk in adulthood is only around 7000 years old. Before that, all adults in Europe were lactose intolerant. The practice of keeping cattle enabled the ones that tolerated milk as adults to spread. They simply had more children. The gene variant that codes for lactose tolerance in adult is in majority in countries like Sweden, with a long history of using diary products. The milk has shaped many of us.

With spider-goat is the other way around. Instead of that we adapted to the milk, we have adjusted the milk to us, to our purposes. I don’t know how this might affect us, from our view of what animals are to our own ability to meet future challenges. I leave that unsaid. Think for yourselves.

Spider pig
Spider pig
Does whatever a spider pig does
Can he swing
From a web
No he can not
He's a pig
Look out!
He is a spider pig!