CAN WE RESTORE THE SPECIES WE'RE MAKING EXTINCT?

For 20,000 years and more the skies of North America darkened Spring and Fall with the migration of from three to five billion birds. They were called passenger pigeons. Deforestation and hunting through the 1800’s changed that. In 1914 the last passenger pigeon died at the Cincinnati Zoo.

The American bison once numbered as high as 30 million. By 1889 humans had reduced their population to about a thousand animals. Fortunately, some humans found reasons to reverse that trend and there now might be as many as half a million bison living on the continent.

We have the ability to destroy the animals, birds, reptiles, and fish with which we share the planet like no other species in history, but we also have the power to stop the destruction, and are now even learning to bring species back.

There have been five mass extinctions on Earth beginning with the end of the Ordovician Era 444 million years ago that saw the end of 86% of all life forms at the time. You’re more likely to think of the last one, the end of the Cretaceous Period 66 million years ago that saw the demise of the dinosaurs. Most of those extinctions have been blamed on sudden climate change, including the asteroid strike that wiped out Dino and his buddies. It takes millions of years for the number of species to reach pre-disaster levels. And, needless to say, those are replacements—the original creatures are gone for good.

Now, many scientists believe we’re undergoing a 6th extinction event, this time caused by…guess who?

The passenger pigeons and the dodo are just two of the 140 bird species, 34 types of amphibian, and at least 77 mammals that scientists say have become extinct since the year 1500, thanks to human activity, especially the destruction of their habitat. Those are the ones we know about. There are still a lot of species, especially insects, reptiles, and amphibians, that have never been classified and could very well be gone before we ever know about them. Some estimates suggest the planet loses hundreds of species a year. And as our powers to shape the environment grow, intentional and not, the rate of extinctions is quickly rising. The International Union for the Conservation of Nature recently predicted that virtually all species currently considered critically endangered and more than two-thirds of endangered species will be gone within the next century. Scientists from Aarhus University in Denmark have calculated that it would take up to 5 million years of evolution to return the planet’s diversity to current levels, and 7 million years to return it to what it was before modern humans showed up and began our path of destruction.

Is there hope? Of course there is. We can curb our out-of-control consumption and stop so much habitat destruction, razing of rainforests, scouring the bottom of the oceans, and spewing plastic and pollution everywhere. Will we? Well, that’s a whole other question.

What about the species already gone, and those it’s likely too late to save? That’s where human technology can actually have a positive side. There are a number of exciting initiatives that point the way to a brighter future.

I’ve mentioned the Svalbard Global Seed Vault in Norway in previous blogs. Built ten years ago to preserve and protect the world’s plant diversity from disaster, it’s reputed to contain a million different varieties now. Seeds evolved to remain dormant when required, so they store pretty well. But what about animals and birds? Projects like the Frozen Ark in Nottingham, UK and the Australian Frozen Zoo in Victoria are working to preserve large collections of frozen DNA from the creatures of the world. That has its challenges certainly. So what if you didn’t have to physically preserve the DNA? For some years now it’s been possible to sequence DNA—transcribe the whole chemical code that determines a species (and an individual’s) cellular makeup. The UK’s Natural History Museum, Royal Botanic Gardens and Wellcome Sanger Institute have joined together in the Darwin Tree of Life Project to sequence Britain’s 66,000 species of animals, plants, protozoa and fungi. Harvard University and other partners around the world are undertaking similar initiatives in the hope that the genetic codes of one-and-a-half million species will eventually be mapped.

Mind you, all of that is like having the full blueprints of a house without the tools or materials to actually build it. We don’t have the technology to recreate plants or animals from scratch like building a Lego set from the instructions. But one day we will.

In Melbourne, Australia, an American scientist named Ben Novak has been working to recreate passenger pigeons by engineering the DNA of ordinary rock pigeons. A team at Harvard is attempting to produce a woolly mammoth by splicing mammoth DNA into the genome of Asian elephants. The tool they use is called CRISPR-Cas9, a combination of repeating RNA (to use as a guide) and the protein Cas9, which allows scientists to basically “cut and paste” DNA in existing sequences. Inserting DNA from an extinct species into the genome of a genetic relative species is how the fictional dinosaurs were created in Jurassic Park (though if anyone’s trying to do that in real life, they’re not admitting it!)

So with all of these efforts to preserve and some day recreate plants and animals, we could theoretically re-introduce forms of life to our planet after they’re gone, or even take them to a new planet somewhere and reform that world in Earth’s image to some degree. That’s very hopeful. Does it excuse us for causing these extinctions in the first place? Absolutely not!

Surely it would be so much better to get our ravenous impulses under control and actually share our beautiful planet with the other species that belong here just as much as we do.

EDITING THE GENOME

A genetic technology discovered in 2012 made news again this month when some researchers at the Salk Institute’s Gene Expression Laboratory were successful in removing the HIV virus (which causes AIDS) from cells that had been attacked. HIV subverts the cell’s own mechanisms to make copies of itself, and embeds itself in the cell’s DNA. Patients have to keep taking drugs for HIV, because it can crop up again years later. The new technique removes the active HIV within the cell but also “snips” it out of the DNA, suggesting it could provide a permanent cure (though the success rate isn’t 100% yet).

The technique has been called “DNA scissors” because it really targets specific segments of DNA and cuts them out. A lot of DNA has repeat sequences known as CRISPRs with spacer DNA between. Cas proteins are special enzymes able to cut DNA, especially the enzyme Cas9 which can target specific spots in a sequence and make a break. The cell’s repair systems then re-splice the DNA strand with the cut segment removed.

The use of CRISPR-Cas9 technology to remove HIV sounds like fantastic news, but the same method can also be used to target and “edit out” other pieces of DNA just as well. That opens up a whole new can of worms.

There are many human afflictions that have been linked to a specific gene or genetic mutation. Presumably, CRISPR-Cas9 could be used to remove many undesirable bits of DNA and cure a variety of chronic genetic conditions like Cystic Fibrosis or Haemophilia. But the question of what is “undesirable” can be very subjective. HIV is bad, but are exceptionally long limbs also bad? What about freckles? Where is the line drawn? There are serious ethical concerns that this technology will be used for “non-therapeutic” purposes. Think of all the money that’s spent on purely cosmetic medical services, trying to achieve a ridiculous standard of beauty. And, of course, the spectre of engineering “ethnically pure” babies raises its ugly head again.

For another thing, although we’ve learned a lot about genetics in recent decades, there’s a lot more to learn, especially about the interconnectedness of our body systems. Only 2% of human DNA codes for the production of proteins that make our cells. The other 98% of non-coding DNA includes instructions and triggers that direct how the coding DNA behaves. There is still much to know about that.

A “slip of the scissors” could cause errors that might have far-reaching consequences: mutations that might be viable but unwelcome or outright dangerous (X-men-type superhuman abilities notwithstanding). And even if no mistakes are made, our deliberate interventions will almost certainly have long-term repercussions. In one of my novel manuscripts I have extremists use an engineered virus to “snip out” the pieces of the human genome connected to violent behaviour, creating a pacifist race. Some might think that would be a great result, but the consequences of such a thing are unknowable. We might find real cause to regret it. The same could be said about eradicating many conditions we generally consider undesirable. We don’t know the long term consequences. There’s no way we can know them.

Think of DNA as building plans. No-one wants unsightly extra nails sticking out to catch the unwary, but removing the wrong nails in the ridge beam of a peaked roof, a lintel of a doorway, or the top of a staircase could spell disaster.

I’m not against technological progress. But I am very much in favour of being sure we have the knowledge to reverse our tampering before we go ahead and do it.

Let’s know more about where all the nails should go before we start pulling them out and the roof falls in.