Taxonomic Inflation

We sometimes describe this as the tensions between ‘splitting’– the tendency to focus on the differences between specimens and argue there are many species – and its opposite, ‘lumping’. These may seem to be capricious practices of shuffling the relevant fossils into lots of small piles or into a few big piles. And woebetide the ‘splitter’ whose book is reviewed by a ‘lumper’! But this isn’t capricious at all. It is strategic. After all, more species means more key specimens, which makes a greater number of museums important and more scientists important too. Cladistic analysis, the most basic analyses of human fossils, assumes that similarities are generally inherited over time from a shared ancestor, rather than transmitted horizontally by admixture between groups – and the best way to make that assumption ring true is to see fossils as species, rather than as subspecies, which could mix. On top of this, there are nationalistic rivalries for claiming the most important hominin fossils. Whose fossils hold the key to understanding our origins – the species from Kenya (Homo rudolfensis), South Africa (Australopithecus sediba), Georgia (Homo georgicus), or Spain (Homo antecessor)? Or is it ‘all of the above’?

What is more, there is such pressure on scientists to name new species – whether justified or not – that many biological areas are experiencing ‘taxonomic inflation’ – the formal recognition of way more species than are really there. This is particularly rampant in our closest relatives, the primates, where the number of recognized species has more than doubled in the last twenty years. It is not as if a great many new species have been hiding from view in the interior of Madagascar or the Amazon rainforest, and have only recently been encountered. Nor is it true that primates are experiencing extraordinarily rapid rates of speciation. The reason that there are twice as many primate species as there used to be is that many of them are endangered, and conservation legislation is often written to protect species. The legal status and protection of primates in the wild is consequently helped by making them species (rather than, say, making them subspecies or local populations). Here the decision is that the conservation needs of the primates are the most important factor. And who would presume to disagree, aside from a heartless pedant?

- Jonathan Marks at Aeon.