About 2,500 years ago, humans settled on the Canary Islands off the coast of Spain. They brought plentiful livestock with them to the once barren islands, creating a whole new ecosystem - one that was perfect for super-sized vultures.
The Egyptian vulture is found throughout southwestern Europe and northern Africa, although its population has declined in the 20th century and it's now listed as endangered, largely due to human intervention. At least once in our history, however, we actually managed to help the vultures become far larger and more plentiful than ever before...though I'm guessing that wasn't the actual plan.
When humans arrived on the Canary Islands 2,500 years ago, the influx of new livestock provided enough dead animals for humans and vultures alike. Recent genetic and morphological research into vultures from the Canary Islands and the Spanish mainland suggest vultures established a population on the islands at almost the exact same time humans did, apparently keen to live on more than just the occasional rodent or sea animal carcass the islands would have had before.
And now, just twenty-five centuries later, the Canary Islands vultures have become bigger and more successful than their mainland counterparts, suggesting an evolutionary shift on a surprisingly short timescale. Indeed, this is one of the first times we've found clear evidence of evolutionary shifts in such a short period of time, particularly for a relatively long-lived species like the vulture.
Researcher Rosa Agudo explains:
"We found that the island vultures are significantly heavier and larger than those from Iberia. The establishment of this insular population took place some 2500 years ago, matching the date of human colonization. Our results suggest that human activity can trigger divergent evolution and that this process may take place on a relatively brief time scale."
So, at least once, human intervention actually managed to help an animal become bigger, healthier, and more plentiful than it was before we showed up. I kind of wish we hadn't chosen vultures to bestow our benevolence upon, but I guess that's what a lack of planning ahead gets you.