When Sudan the white rhino was put down by his carers earlier this year, it confirmed the extinction of one of the savannah’s most iconic subspecies.
Despite decades of effort from conservationists, including a fake Tinder profile for the animal dubbed ‘the most eligible bachelor in the world’, Sudan proved an unwilling mate and died – the last male of his kind.
His daughter and granddaughter remain – but, barring some miraculously successful IVF, it is only a matter of time.
The northern white rhino will surely be mourned, as would other stalwarts of picture books, documentaries and soft toy collections.
But what about species of which of which we are less fond – or perhaps even entirely unaware?
Would we grieve for obscure frogs, bothersome beetles or unsightly fungi?
Extinction is, after all, inevitable in the natural world – some have even called it the ‘engine of evolution’. So should extinction matter to us?
First of all, there are strong practical arguments against biodiversity loss.
Variation, from individual genes to species, gives ecosystems resilience in the face of change.
Ecosystems, in turn, hold the planet steady and provide services essential to human welfare.
Forests and wetlands prevent pollutants entering our water supplies, mangroves provide coastal defence by reducing storm surges, and green spaces in urban areas lower city-dwellers’ rates of mental illness.
A continued loss of biodiversity will disrupt these services even further.
Seen in this light, the environmental damage caused by resource extraction and the vast changes that humans have wrought on the landscape seem extremely high risk.
The world has never before experienced these disturbances all at the same time, and it is quite a gamble to assume that we can so damage our planet while at the same time maintaining the seven billion humans that live on it.
Although the unregulated plundering of the Earth’s natural resources should certainly worry those brave enough to examine the evidence, it is worth specifying that extinction is an issue in its own right.
Some environmental damage can be reversed, some failing ecosystems can be revived. Extinction is irrevocably final.
Studies of threatened species indicate that, by looking at their characteristics, we can predict how likely a species is to become extinct.
Animals with larger bodies, for example, are more extinction-prone than those of smaller stature – and the same holds true for species at the top of the food chain.
For plants, growing epiphytically (on another plant but not as a parasite) leaves them at greater risk, as does being late blooming.
This means that extinction does not occur randomly across an ecosystem, but disproportionately effects similar species that perform similar functions.
Given that ecosystems rely on particular groups of organisms for particular roles, such as pollination or seed dispersal, the loss of one such group could cause considerable disruption.
Imagine a disease that only killed medical professionals – it would be far more devastating for society than one which killed similar numbers of people at random.
This non-random pattern extends to the evolutionary ‘tree-of-life’.
Some closely related groups of species are restricted to the same threatened locations (such as lemurs in Madagscar) or share vulnerable characteristics (such as carnivores), meaning that the evolutionary tree could lose entire branches rather than an even scattering of leaves.