Spider Goat, Spider Goat . . . Her Milk Could Make a Bulletproof Coat


Scientists inserted the silk-making gene from a golden orb spider, such as the one shown here, into a goat to produce goat’s milk that contains spider silk. (Photo credit: Christopher Meder/Getty Images)

Genetic engineering is nothing new. In fact, it’s a practice that’s literally thousands of years old. For centuries, humans have selectively bred plants and animals in an attempt to pass along desired traits. Today, however, genetic engineering has taken the practice to a new level.

Freckles is the world’s first and only “spider goat.” While she looks and acts like any other goat, milk Freckles and you’ll discover her milk contains spider silk. Although this may seem to be taking “cross-breeding” to ridiculous extremes, to biologist Randy Lewis of Utah State University it’s just a logical extension of animal husbandry. It’s simply using what you know about animals to get the traits you want.

The obvious question is why mix spiders and goats? And, more importantly, how do you even do such a thing? The answer to the first question is deceptively simple: spiders are too hard to farm. Confused? Well, it all has to do with a desire to find ways of getting more spider silk, a substance that is flexible, yet stronger than steel, and can absorb a great deal of moisture. In recent years, scientists have become very interested in spider silk, which seems to be the perfect raw material for the production of such things as better artificial limbs and bulletproof vests. So far, spider silk has no synthetic alternative, and large scale farming of spiders to mass produce it seems impossible, because the arachnids don’t get along very well in groups. They’re generally loners who will attack others readily.

Goats, by contrast, are easy to farm. Interestingly, a protein in goat’s milk closely resembles the protein in spider silk. So, Professor Lewis and his team took the gene that produces the silk from a spider and inserted it into the DNA sequence that codes for milk production in the udders of the goat. They then took this modified DNA, placed it among the other DNA in a female goat’s ovum, and implanted that egg into Freckles’s mother. And that’s how Freckles came to be!

When Freckles gets milked, the milk is then taken to a lab for processing. The processing leaves only the silk proteins, which are then lifted out, strand-by-strand, with a glass rod. While the potential uses for the material may seem endless (the reason the work is so heavily funded), whether or not Freckles and her goat sisters will be the suppliers of it is still up for question. Goats need to be fed, housed, and cared for, and even then it’s not certain that ovum containing the genetically altered DNA will result in a female goat capable of producing the protein. Due to probability in genetics, only a certain number of goats will end up with the gene. Researchers, therefore, are currently looking at the possibility of placing the gene into alfalfa plants. The plants would grow far more quickly and certainly be much cheaper to produce.

The mere existence of Freckles, the spider goat, brings to light even more issues than whether or not the world will see a deluge of spider silk products. While some may see her as the logical extension of selective breeding, others see her as representing a new era of biological engineering where organisms will be literally assembled from scratch. Genetic engineering may not be a new concept, but the idea that living organisms, with their inherent complexity and genetic variability, may soon be subject to assembly line construction is one that makes some feel uneasy.

For now, Freckles remains a very unique creature, a creature that never could have existed until this time, and surely a kind of symbolic figure to those who will follow her.

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