How Humans Drove Cyprus Dwarf Hippos and Elephants to Extinction

Picture yourself living beside the eastern Mediterranean 14,000 years ago. You are a skilled navigator of the small boats made by you and the other people in your village, drawing your livelihood from both land and sea.

Yet life has become harder: there is nowhere near as much game or fish as there was in your childhood. Perhaps you need to search elsewhere for something to eat.

Imagine then travelling farther than you ever have in your small boat, perhaps with several companions, and noticing something ahead on the horizon. Could it be an island?

An island of tiny elephants and hippos

Welcome to Cyprus as the world begins to emerge from the last ice age. You are the first person to see this vast, densely wooded island, abundant with potential food.

After pulling your boat ashore to explore, you are astonished by what confronts you: hippos the size of boars and elephants as large as horses, both of which appear infant-like to you. They are everywhere, and the long voyage has left you hungry.

The small animals appear unafraid. You kill several without difficulty and preserve as much meat as possible for the lengthy return journey.

Back home, you eagerly tell everyone in the village about your discovery. Before long, a large expedition is organised to return to the island.

Naturally, we can never know whether events unfolded in this way, but it is a credible account of how, and when, the first people may have reached Cyprus. It also demonstrates how humans could have swiftly caused the extinction of the tiny hippopotamus Phanourios minor and the dwarf elephant Palaeoloxodon cypriotes.

Dwarf ‘giants’

Cyprus was not alone among Mediterranean islands in having dwarf animals. Crete, Malta, Sicily, Sardinia and numerous other islands likewise supported their own dwarf elephants and hippos.

Island dwarfism, in which a large mainland species evolves a smaller body in response to more limited resources and fewer predators, is actually widespread. Regrettably, this same process leaves such animals particularly susceptible to sudden environmental shifts, including the arrival of new predators such as people.

The Cypriot dwarf hippopotamus was the Mediterranean’s smallest dwarf hippo. Genetic evidence indicates that it split from the common hippopotamus (Hippopotamus amphibius) about 1.5 million years ago.

The Cypriot dwarf elephant measured less than 10 percent of the size of its mainland predecessor, the straight-tusked elephant (Palaeoloxodon antiquus), which lived in Europe and western Asia during the Middle and Late Pleistocene.

A controversy over extinction

For many years, a large number of archaeologists and palaeontologists did not accept that humans played any role in the disappearance of Cyprus’s two “megafauna” species.

Sceptics believed either that people did not arrive until long after these animals had vanished, or that the earliest settlers were too few in number to eliminate whole species.

Earlier this year, we demonstrated that humans reached Cyprus between 14,000 and 13,000 years ago, well before the extinction of hippos and elephants. We also found that, within a few centuries of their arrival, the human population probably increased to several thousand. What remained unclear was whether that population was sufficient to wipe out the dwarf hippos and elephants.

Our research, published today, resolves that issue by bringing together several types of mathematical model.

Could a small human population cause extinction?

Although these animals have been extinct for a long time, palaeontological evidence allows us to estimate their body masses and therefore infer aspects of their probable populations. The dwarf hippo weighed about 130kg, while the dwarf elephant weighed a little more than 500kg.

We can also convert body-weight estimates into likely figures for population size, lifespan, survival and fertility. Data gathered from living related species, including the pygmy hippo and African elephant, can even be used to estimate how quickly these animals would have reproduced.

Using this evidence, we created computer models showing what might have happened to Cyprus’s two mini-megafauna species after human hunters arrived. We calculated the likely effectiveness of human hunters, the time required to process each carcass and the energy hunter-gatherers need to survive.

We further estimated the share of the human diet made up by these species, and how that share may have altered as dwarf hippo and elephant populations declined.

We found that a human population of only between 3,000 and 7,000 could readily have driven the dwarf hippos, followed by the dwarf elephants, to extinction.

According to our model, the entire process would have lasted under 1,000 years. That estimate corresponds with the order of extinction suggested by the palaeontological record.

Our findings offer compelling evidence that Palaeolithic people in Cyprus were at least partly, and perhaps wholly, responsible for megafauna extinctions in the Late Pleistocene and early Holocene.

Cyprus provided an excellent setting in which to test our models, as the island presented ideal conditions for investigating whether human arrival ultimately caused its megafauna to disappear.

This was because Cyprus was a comparatively straightforward test case: an island covering around 11,000 square kilometres at the time and home to only two megafauna species.

Consequently, our research advances understanding of how even limited human populations can disturb ecosystems and trigger substantial extinctions, especially during periods of rapid environmental change.

Corey J. A. Bradshaw, Matthew Flinders Professor of Global Ecology and Node Leader at the ARC Centre of Excellence for Indigenous and Environmental Histories and Futures, Flinders University; Christian Reepmeyer, Deputy Director – Oceania, German Archaeological Institute; and Theodora Moutsiou, Special Scientist, University of Cyprus

This article is republished from The Conversation under a Creative Commons licence. Read the original article.