Island of the Tiny People

In 2003, the field of human evolution was rocked by the discovery of “hobbits,” an ancient species of human relatives who stood barely more than a meter tall. Named Homo floresiensis, they lived on the Indonesian island of Flores, and for years researchers argued over whether they represented the first-known human case of “island dwarfism” or if these ancient individuals had some sort of disease causing their short stature. If they were diseased, what disease did they have? If they were a legitimate species, where did they come from?

The disease hypothesis has mostly fallen out of favor. Numerous studies have countered suggestions that H. floresiensis had microcephaly or hypothyroidism or other proposed conditions. On Wednesday, a new study provided evidence against Down Syndrome being responsible for the fossils’ appearance. So it seems the “hobbits” were their own species, but that leaves still many questions.

Human Environmental Engineering Goes Back a Long, Long Time

An alien species visiting Earth would find a planet clearly dominated by one species. It’s no secret that humanity has a major influence on all aspects of Earth processes – we’ve covered major portions of land surface in stone and asphalt; we’ve cleared natural landscapes and driven an ever-increasing number of species to extinction; we’ve filled the oceans with plastic and the atmosphere with greenhouse gases. This planet is very firmly in the grip of human activity.

But this legacy of environmental modification goes back further than we generally appreciate. Today’s issue of PNAS has a special section devoted to human evolution, and one paper outlines the modern understanding of the many ways our species has affected the physical world around us, and just how long we’ve been doing it. The fact is that our modern explorers – the intrepid adventurers of the past few centuries who discovered lands populated only by indigenous peoples or long-gone civilizations – were alien visitors to parts of the planet already dramatically transformed by human influence.

Here are some of the ways our species has been shaping natural environments since long before written history:

The Mystery of the Sunken City of Zakynthos

This scientific discovery reads like a science-fiction mystery novel.

It starts in 2014, when a group of tourists visiting the Greek island of Zakynthos decided to go snorkeling. While exploring the shallow ocean waters close to Alikanas Bay they stumbled upon what appeared to be the remnants of a sunken civilization: flat pavement stones and the circular bases of collapsed colonnades. Perhaps these were lost fragments of a city port submerged by the sea?

The divers took pictures and uploaded them online, where they reached the attention of Greece’s Ephorate of Underwater Antiquities, who sent in an archaeological investigation team. The team discovered something very odd: there was no pottery, no coins, no signs at all of any human life. If this had once been a city, who lived there? Who built it? And why didn’t they leave behind any artifacts?