To lump or to split? Deciding whether an animal is a species or subspecies profoundly influences our conservation priorities

Noah never reckoned with trinomials. Modern Creationists, grasping for footholds in the post-Darwinian world, maintain that Noah took 1,398 kinds of animal aboard his Ark, as the floodwaters gathered on the Mesopotamian plain. ‘Kind’, they argue, is a Biblical classification that corresponds to the modern ‘family’, and not, as you might imagine, to the modern concept of ‘species’. If Noah had accessed a modern taxonomic catalogue, he might have found himself with a cargo of up to 30,000 varieties of mammal, bird and reptile; if he had factored in the insects and arachnids, his Ark would soon have been foundering under the weight of about 1.1 million different species.

The trinomial – the subspecies, described by a Latin name that adds a third classifying component, as in, say, Passer domesticus biblicus, the Palestine house sparrow – further inflates Noah’s hypothetical menagerie. By how much, it’s hard to say; trinomials are tricky, as we shall see. We can say that instead of just one wolf he could have had as many as 38 (or, rather, 76, as of course the animals went in two by two). Instead of one song sparrow pair he would have had somewhere between 20 and 50. Of anoles – small iguanian lizards – he would have had a dramatic abundance, the Ark crawling with perhaps 427 species and a further 144 subspecies.

Noah would no doubt, by this time, have been making frantic calculations about load distribution, ballast, stress and tipping balances, not to mention the logistics of food supply and waste disposal. What, he might have wondered, brushing an anole from his sleeve, is the point of all these subspecies?

He would not have been alone.

Both scientifically and in broader society, we are tied to the species as the bedrock unit of the animal kingdom. Species are, for want of a better term, easy. Look, for instance, at how we speak about extinction. We talk about the dodo and the great auk, the blue whale and the giant panda. But there are various subspecies that deserve to be better known and protected. Trinomialism – resisted for a long time by some in the establishment – offers not only scientific clarity and variety, but an enriched view of the living world and our relationship with it.

The species has long been the basic unit of zoology. Ernst Mayr’s 1951 definition still fits: ‘An aggregate of interbreeding natural populations which are not only reproductively isolated from other such aggregates but also ecologically specialised sufficiently so as not to compete with other such species.’ By thinking in species – as we now do, all of us, through long habit – we minimise grey areas and disorderliness, and at the same time break the sprawling animal world into manageable parts, manipulable segments, just as we do with, say, time (centuries, decades) or geographical space (countries, states, counties). As in those cases, though, we are kidding ourselves if we insist that our lines of delineation really mean anything, in a fundamental sense. Our borders are always porous.

The dawning of Darwinism led to the slow realisation that the species was not an immutable form, but rather an evolutionary happenstance. It showed that nature was a work in progress, and that the Grey Area was alive and well and living among us. And it brought to life a debate that has been rattling on ever since. Where do we draw our lines? Do we ‘lump’, and pull large numbers of slightly different animals together under a single name, or do we ‘split’ and go the other way, endlessly divvying up animal types as new variations arise? What even are subspecies, these neither-this-nor-that intermediates, these creatures caught between binomials, like actors surprised mid-costume change?

You might think that these kinds of controversy would have been cleared up for good by the brisk, progressive scientism of the later 20th century. Modern science, surely, has no place for grey areas and guessing games. But the tension between lumpers and splitters remains in taxonomy. It mostly plays out in textbooks and at conferences, in taxonomic panel meetings and scientific journals. However, the winners and losers determine our value judgments of the living world.

Focusing on the differences between populations brings us closer to an animal’s eye view of nonhuman life

After all, the species is such a solid part of laypeople’s vocabulary, it’s natural that it should also be the working base unit of wildlife conservation, at least in its public-facing forms. ‘Endangered species’ is a familiar phrase; ‘endangered subspecies’ or ‘endangered genus’ less so. The species is the unit of the International Union for Conservation of Nature’s ‘red list’ of at-risk creatures. When we think about the living world, we think in species.

And when I say ‘we’, of course, I’m still thinking in species, because I’m talking about humans, Homo sapiens. The interesting thing is that we’re the only species that cares about species. It’s not exactly right to say that we invented them – Mayr’s definition describes a real phenomenon – but it’s only we humans who give the idea any weight, any real meaning. A starling, for instance, doesn’t care whether it’s the last of its kind or (as it, in fact, is) one in 150-odd million. ‘I’m the last me,’ it thinks, and lives and feels and acts on that basis. I think we can learn something from that starling.

Subspecies – and there are, for the record, 12 subspecies of the common starling – are a taxonomic step too far for some biologists. No-one denies that the differences they embody are real, but for more than a century, many have maintained that the trinomial is just administrative lumber, a systematist’s indulgence, unwieldy, unhelpful and unnecessary. ‘As for trinomials I look upon the system as destructive,’ wrote the ornithologist Richard Bowdler Sharpe in 1909. ‘I consider that the burden imposed upon the zoologists who follow this method for the naming of their specimens will become too heavy, and the system will fall by its own weight. That races or sub-species of birds exist in nature, no one can deny, but, to my mind, a binomial title answers every purpose.’

It’s true that the ‘subspecies’ concept opened a large can of worms (interestingly, the taxonomy of worms is itself a particularly fraught field, a can of worms within a can of worms). But there’s another way of looking at trinomials. Splitting – focusing more narrowly on the differences between populations – might bring us closer to a bird’s eye view, a worm’s eye view, an animal’s eye view of nonhuman life. Species-centric thinking means we’re inclined to value an animal’s life relative to the scarcity or abundance of its species. What this ratcheting scale means is that we only really value the individual animal when there’s just a few of them left – that is, when it’s already too late.

In a sense, every animal is the last of its kind. It just depends what we mean by ‘kind’.

That brings us back to Noah, and the Creationists’ pragmatic winnowing of life’s wild diversity. So let’s look at the issue in terms Noah would have understood. How many kinds of animals do we really need?

One thing we do know is that, in the short term (the very short term, in fact) there are going to be fewer kinds of animals. What in Darwinese are called selection pressures – that is, the things that make life harder for wild things, and winnow out those less well adapted – are getting only more intense. For many animals, they are not so much selection pressures as extinction pressures.

More than 500 species of land animal are at grave risk of going extinct in the next 20 years, according to the findings of a 2020 analysis. You can chop this figure up how you like (get splitting, factor in subspecies, and bump it up way above 500, or go Old Testament on it, and lump it down to a smaller number of families). We may arrive at different numbers of species, subspecies, families, ‘kinds’, whatever, but in reality – in the wild, rather than on paper – it’s the same number of animals dying off. So perhaps it doesn’t matter how we divvy them up?

The animals themselves may not care, but biodiversity is the key here – something that only Homo sapiens can perceive. Biodiversity isn’t just about ensuring nature is a fun zoo for us to gawp at (though, if we’re being honest, it is partly about that). It’s central to the maintenance of healthy, dynamic, resilient ecosystems. If we’re serious about large-scale conservation, we have to be serious about biodiversity, and if we want to do that, we have to be measuring it.

Crucially, though, this measurement doesn’t have to be just about species. Some biologists use what’s called the evolutionarily significant unit (ESU) to single out not just species but also subspecies and isolated populations (subspecies-in-waiting, sub-sub-species) that are believed to be of particular value in terms of diversity, and therefore particularly in need of protection or support.

The losses are no less profound because there’s another subspecies in the next state, or on the next island

To understand what happens when we don’t take this more nuanced view, consider the heath hen – Tympanuchus cupido cupido.

This subspecies of prairie-chicken – a large grassland grouse – was once widespread in the north-east United States, but overhunting and habitat loss steered it into a genetic bottleneck from which there was no way out. The last remnants of the population, isolated on Martha’s Vineyard, were finished off by predation, disease and wildfire; the last individual (or ‘endling’), a male known as ‘Booming Ben’, boomed his last in the spring of 1932.

It would be nice to say that Ben’s death, and with him the extirpation of the subspecies T c cupido, taught us how to cherish and protect wild animals not only at the species level but at the localised, specialised trinomial level – how to find value in the particular as well as in the general. But what we find instead is that, nearly a century on, another prairie-chicken subspecies, Attwater’s prairie-chicken, is functionally extinct as a wild bird, sustained only by re-release programmes in a handful of Texas locations. The greater prairie-chicken holds on, for now, but there are no other subspecies after that; three strikes and it’s out.

There’s a tendency to view extinctions of this kind as sub-extinctions, which don’t really count. We see them as drills, trial runs, from which we can take lessons for next time. In a sense, it’s true, these are subsidiary losses; they are lost battles in a wider war. But they are also endings in themselves. They are no less total or profound because there’s another subspecies in the next state, or on the next island along.

Similar next-time-will-be-better rhetoric swirls around another, perhaps more celebrated subspecies: the northern white rhinoceros, Ceratotherium simum cottoni. Only two remain, under armed guard in Laikipia County, Kenya. There’s no way back for them – of course, there’s no way back for anyone, in the long run, but in their case death will have a depressing double meaning. What is to be done? Well, we will, of course, Learn Lessons.

‘Lessons learned are being put into practice,’ says the NGO Save the Rhino, explaining how the demise of C s cottoni will inform efforts to conserve the next rhinos on the rank, the Javan and Sumatran species. It’s worth noting that, prior to the 20th century, there were three subspecies of each of these; today, four of these subspecies – two Javan, two Sumatran – are either extinct or as near to extinct as makes no difference.

‘In the ideal world,’ says Adam Hart, a conservation biologist at the University of Gloucestershire in the UK, ‘conservation efforts should be flexible and inclusive, targeting both species and subspecies to fully preserve biodiversity, but in the real world defining subspecies and ESUs can be difficult.’

Indeed, we are so wedded to the primacy of the species as a unit that the preservation of a mere subspecies can be a hard sell. Look on social media, and see how posts about saving the white rhino – an expensive and complex affair – attract sceptical responses along the lines of ‘It’s only a subspecies!’

Similarly, a segment in the BBC’s recent wildlife series Asia highlighted the grave plight of the Gobi bear. There are, Sir David Attenborough told us, fewer than 40 Gobi bears left. It’s a miserable statistic. But it’s worth thinking about exactly what’s being said here. The Gobi bear is, as it happens, a subspecies, a significant sub-population of the brown bear Ursus arctos. But what if it wasn’t? ‘There are 40 Gobi bears left’ lands a little differently than ‘There are 40 brown bears left in this part of the Gobi desert’; the former sounds like a call to action, no time to lose! – whereas the latter is more, well, who cares? What’s a few brown bears, here or there?

What this boils down to, again, is the question of what’s real – what’s significant, what means something.

When subspecies become more distinct – more seen – it does change how we value them. ‘Taxonomic assignments inevitably shape perceptions of biological diversity,’ wrote John C Avise in 1992. ‘Yet once a Latin binomial or trinomial is in the literature, the group of organisms to which it refers almost automatically assumes an aura of reality that may or may not be commensurate with its true evolutionary distinctiveness.’

Jon Dunn, a naturalist and the author of the book Orchid Summer (2018), offers the bee orchid genus Ophrys as an example. ‘Back in the 1980s, I guess botanists would have recognised maybe 150 species of morphologically distinct Ophrys across Europe,’ he tells me. Now there are more than 400, thanks to a splitter called Pierre Delforge, author of Orchids of Britain and Europe (1995), who claimed to have identified minute differences between the plants.

‘Some folk love this – more things to see! – but others have taken a vehemently different stance,’ he tells me. ‘Scientists affiliated with Kew [the Royal Botanic Gardens in London] have looked at Ophrys DNA and determined that there are fewer than 20 Ophrys species in Europe. Both positions can’t be correct.’

And it’s not entirely an academic question, as Dunn explains.

‘Let’s say someone on the island of Rhodes wants to build a hotel complex in an old and unremarkable coastal olive grove,’ he proposes. ‘It’s also home to one of a few populations of Ophrys colossaea, a Rhodian endemic “species”, according to Delforge. And it does look different to other Ophrys – it’s a big, distinctive beast – but according to Kew that’s just part of Ophrys fuciflora – a subspecies of it, at best. Let’s also say that Rhodes has good planning regulations. A valid objection to that proposed hotel build would be if a significant proportion of the world population of Ophrys colossaea would be wiped out. But if it’s just a subspecies of something that’s widespread across southern Europe? Maybe it doesn’t matter so much after all.’

The subspecies has the potential to tap into a powerful sort of emotional localism

Reassuringly, some conservation bodies have begun to take the view that subspecies do matter. Birds, in particular, are increasingly seen through the trinomial lens, largely because so many people enjoy (and are good at) picking out the tiny distinctions that separate populations – which is not the case with, say, slime moulds or seaweed flies. Back in 2006, for example, the Biodiversity Reporting and Information Group, which oversees the monitoring of biodiversity in the UK, decided that its priority list for bird conservation should operate not at the species level but at the level of ‘race’ – that is, subspecies – singling out endemic examples like the black grouse, the lesser spotted woodpecker and the willow tit.

Today, it’s believed that there are 32 subspecies that occur only in the British Isles and Ireland, local varieties of birds that for the most part are abundant in other territories, in subtly different forms – British chaffinch, Scottish linnet, Hebridean dunnock, and so on. Of particular note are the island races of the wren, Troglodytes troglodytes: the Hebridean wren, the Shetland wren, the Fair Isle wren and the St Kilda wren – the last inhabiting a remote archipelago of less than 3.5 square miles in area, but nevertheless sufficiently iconic to have appeared on a postage stamp. In cases like this, the subspecies has the potential to tap into a powerful sort of emotional localism; there exists a sense of investment or stewardship – if not ownership – among the human populations of these places.

It’s certainly worthwhile to ask whether, in the interests of conserving biodiversity, we should give more weight to these local types, these variations on a theme that can only add depth and richness to our regional ecologies (even if it takes an expert to tell them apart). Biodiversity is hugely important of course, but there’s a danger that it may blind us to more intuitive metrics of conservation. Evolutionary significance is not the only kind of significance.

I believe that subspecies matter. But perhaps appreciating them is better thought of as a step in the right direction, away from the species-centric lens, and towards seeing animals in all their remarkable individual variety.

Without taking that step, we may be stuck with the sort of ruthless attachment to taxonomic preservation that can even lead to harm in the name of a perceived greater good. In the UK, not so long ago, we exterminated – in the literal, blood-in-the-water sense – our population of ruddy ducks, because some had made it to Spain and were interbreeding with white-headed ducks (their near cousins, but a distinct species, just about). If this had continued, the white-headed duck would have been, as a species, subsumed by the ruddy duck. It would have been a subtle, bureaucratic extinction, death by a technicality, extermination without a shot fired. But in any case, now there are no ruddy ducks in my home country at all (but not to worry, because there are still plenty in the US).

I liked our ruddy ducks. I miss them. I think there’s a case to be made for birds (and mammals, insects, reptiles, plants) that are genetically very boring, that do not belong to unique populations – for animals that happen to be here, but might just as well be over there. I think there’s a case to be made for keeping them here because we want them here. Arguments from taxonomy sound much more impressive than that, but those are still only human arguments, built from human priorities.

Perhaps we might also make some room for the priorities of the animals themselves.

Sometimes when a creature dies, it is the last of its ‘kind’, locally or globally. It vacates its Latin binomial or trinomial, leaving it unused like an empty house or a dog’s old collar – and that feels substantial, meaningful, mournable. But we needn’t always wait for these last few desperate moments to mourn these declines and disappearances; there are other forms of absence that come earlier – which in fact are right before us now, in great multitudes. We ought to remember that the animals don’t care either way about what box we put them in, or how many Latin names they have. They just want to survive.