Humans are threatening to wipe out over 50 billion years of unique evolutionary history, according to new research reported in the journal Nature Communications this week.
Scientists from Imperial College London and Zoological Society of London found that parts of Earth with the greatest amounts of unique evolutionary history are being degraded due to "unprecedented" levels of human activity. This includes areas that are home to some of the planet’s most “weird and wonderful” creatures, such as the Caribbean, large swathes of Southeast Asia, and the Western Ghats of India.
The researchers gauged how many years of unique evolutionary history an animal species represents by looking at the phylogenetic differences between species on the "tree of life" and noting how much evolutionary history separates them from their nearest relative. This was then combined with extinction risk data for around 25,000 terrestrial species and information about human pressure on different animal environments across the world.
In total, they estimated that at least 50 billion years of evolutionary heritage is under threat by human activities, although the actual figure is likely to be even higher as many rare species lack adequate extinction risk data.
Reptiles, the main focus of the study, are poised to lose up to 13 billion years of evolutionary history. Not only do reptiles represent the most evolutionary diverse class of animals, but many species with a long history were also found to live in areas under high or very high human pressure, such as the Caribbean, the Western Ghats of India, and Southeast Asia. Just 5 percent of the reptiles’ evolutionary history was found to be in species living in areas with little or no human pressure.
The greatest losses of evolutionary history will be driven by the extinction of entire groups of closely related species – the seemingly sturdy branches on the evolutionary tree that find themselves in a risky position. This, for example, would include tapirs and pangolins, which are closely related to each other but find themselves under an intense amount of pressure from human activity. If these branches of the evolutionary tree are chopped, the number of evolutionary years lost would be huge.
However, the researchers also show concern for highly evolutionarily distinct species that represent the ends of extremely long, thin, and lonely twigs. This refers to the most unusual creatures on the family tree that have few close relatives and carved their own evolutionary path, including the ancient Chinese crocodile lizard (Shinisaurus crocodilurus), the purple frog of the Western Ghats (Nasikabatrachus sahyadrensis), the shoebill bird of Africa (Balaeniceps rex), and the bizarre long-fingered lemur known as the aye-aye (Daubentonia madagascariensis). Unfortunately, many of these more unique and strange creatures find themselves under heaps of human pressure too.
"These are some of the most incredible and overlooked animals on Planet Earth," lead author Rikki Gumbs, from the ZSL's EDGE of Existence programme and the Department of Life Sciences at Imperial College London, said in a statement.
"Our analyses reveal the incomprehensible scale of the losses we face if we don't work harder to save global biodiversity," he added.