I lament the way that humans have trampled through the Earth’s fragile environment. We’ve already destroyed a lot of habitats, and with it a dismaying number of species. You can be sure we’ll destroy a lot more before we fall into extinction ourselves, which is where we’re obviously heading if we carry on as we are.
Many of those extinctions have happened just in the last few decades, but the human impact on nature has been traced back to Pliestocene times. For a long time there was debate: was the repeated destruction of Pliestocene megafauna, straight after humans arrived, a coincidence? Due to other factors? What? The jury is still out to some extent – there were probably multiple factors. But there’s no question that humans were one of them – and a very large part of the calculation.
The last of those collisions, incidentally, occurred in the last millennium when New Zealand was reached by humans for the first time. Until the late thirteenth century, New Zealand carried its ancient biota – a literal ‘lost world’ with its Mesozoic-era forests, ferns, giant birds and no mammals other than bats, untouched by humans. Within a short period of human arrival, much of it had gone – repeating the same pattern evident in Europe, Asia, Australia and the Americas.
Can this be undone? Technology offers ways, largely through genetic engineering, although inevitably – human nature being what it is – that work will likely cause problems. There’s a project on to reverse-engineer theropod dinosaurs out of chickens. It’s not hard. Birds didn’t evolve from dinosaurs – they are dinosaurs, and they still have the genes of their jawed and tailed Mesozoic cousins. We have but to switch them on, and birds will grow theropod-style leg bones, tails, and toothed jaws. Already gene-tinkering has produced chicken embryos with dino legs and others with dino-jaws.
To my mind that sets to rest any debate about what birds are – but it’s not cool. We don’t know what consequences these changes will have. I’m not thinking of flocks of ravening dinochickens roaming suburban neighbourhoods and terrorising cats. Our knowledge of genes is incomplete, despite our conceits of being ‘advanced’ and ‘sophisticated’. It was only recently, for instance, that ‘junk’ DNA – stuff that didn’t have an obvious purpose – was found to have functionality after all. One nasty scenario is that we accidentally create an easier disease vector for strains of bird flu that we only discover after ChickenosaurusTM has become the new must-have status pet for households. It’s unlikely, but it wouldn’t be good to find out the hard way. The other issue is that, for all that genetic modification is declared ‘safe’, we don’t know the long-term consequences, or what happens when modified genes ‘leak’ into the wild.
The thing about gene engineering, though, is that it offers ways of recovering creatures lost to our own human nature. There’s a been talk of rebuilding the mammoth using CRISPR genetic splicing techniques and modern elephant cells, but it’s not actually possible. The issue is the quality of mammoth DNA. The stuff’s fragile, and being able to analyse the genome in preserved animals doesn’t mean the same material is viable as a building block for a life-specimen.
More recent extinctions offer no better potential. Here in New Zealand the obvious ‘recent loss’ is the huia. This wattlebird, a close relative of the kokako, ranged on the east coast of the North Island and was last seen at the end of 1907, when W. W. Smith observed three in the Tararua ranges north of Wellington. Other sightings since, one as late as the 1960s, have been unsubstantiated and the bird is considered extinct. There was a proposal in 1999 to clone huia from DNA in preserved specimens. There were a fair number in public and private hands. (My great aunt used to have two – a male and female – which sat in their china cabinet. I don’t know what became of them.) However, once again, none were well enough preserved to provide DNA.
So is there hope? Yes, given the right circumstance. Think quagga (Equus quagga quagga). This zebra sub-species with its distinctive colouring and lack of hind-quarter stripes lived primarily in South Africa and was declared extinct in the wild in the late 1870s. The last known specimen died in Amsterdam Zoo in 1883. Again, preserved examples exist. And again, the DNA in them isn’t good enough. However, they were long considered a close sub-species of other zebra – not a separate species. This means its genes are in other zebra, so it’s possible to recover most of the quagga’s unique features – notably its colouration and stripe pattern – by selective breeding.
Reinhold Rau began doing just that in 1987 with the Quagga Project, though it’ll take a while to show full results. Although the species status of the quagga was still debated when that project began in the 1980s, a 2005 study showed that the quagga had diverged from the plains zebra only between 290,000 and 120,000 years ago. So yes, back-breeding is eventually going to produce a zebra that’s pretty much quagga-like.
This means we can undo at least one piece of the extinction-damage that humans seem to be so expert at creating.
Copyright © Matthew Wright 2017