Rhino horns have shrunk significantly over the last century

It’s all because of hunting.
Loukia Papadopoulos
Rhino horns have shrunk over the last century.jpg
Rhino horns have shrunk over the last century

AOosthuizen/iStock 

Research out of the University of Cambridge is revealing that rhino horns have significantly decreased in size over the last century likely due to hunting, according to a press release by the institution published on Tuesday.

Smaller over time

“The researchers think rhino horns have become smaller over time due to intensive hunting. Rhino horns command a high price and are in demand both as a financial investment, and for their use in traditional medicines in China and Vietnam,” said the statement.

The scientists discovered this fact by comparing photographs of rhinos over time. They were able to deduce from images the evolution of the horns’ size.

“We were really excited that we could find evidence from photographs that rhino horns have become shorter over time,” said Oscar Wilson, formerly a researcher in the University of Cambridge’s Department of Zoology, first author of the report. Wilson is now based at the University of Helsinki, Finland.

He added: “Rhinos evolved their horns for a reason - different species use them in different ways such as helping to grasp food or to defend against predators - so we think that having smaller horns will be detrimental to their survival.”

To ensure their work was accurate and truly reflected a horn size decrease, the researchers also measured other body parts on each rhino photograph, including body and head length.

The photographs themselves showed the interesting evolution of our relationship with the large mammals. Early pictures depicted a lot of hunting. There was even a photograph of American President Theodore Roosevelt, taken in 1911, standing triumphantly over a black rhino he had just killed.

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Rhino horns have shrunk significantly over the last century
Theodore Roosevelt in 1911

However, more recent images depicted the animals unharmed in their natural habitat showcasing that we have come to understand the importance of protecting and preserving the species.

A change in focus

“The images suggest that there was very little effort to promote rhino conservation to the public before the 1950s. But after this the focus suddenly changed from hunting the animals to trying to keep them alive. The researchers say this shift coincides with the collapse of European empires, when African countries became independent and European hunters no longer had easy access to Africa for hunting,” revealed Cambridge’s statement.

Overall, the researchers looked at thousands of photographs. The work is important not only from an evolutionary perspective but also as a way to highlight how crucial the preservation of endangered species is.

Although rhinos are currently not on that list, their excessive hunting could have easily seen them join the ranks of animals in danger of total annihilation especially considering that the last male Sumatran rhino died in May of 2019.

The report is published in the journal People and Nature.

Abstract:

Online image repositories can offer a freely accessible, information- rich and cost-effective alternative to museum collections for studying long-term changes in human interactions with nature and ecological and evolutionary change. The Rhino Resource Center (RRC) is one example, curated by experts and holding a collection of >4000 rhino images, including both artistic portrayals (1481–2021) and photographs (taken between 1862–2021), and rep-resenting a potentially valuable case study to investigate the utility of online image repositories for research into large vertebrates and, potentially, other well-recorded smaller taxa. The five extant species of rhino are all threatened by habitat loss and human hunting and therefore are an important focus for conservation research

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