South Africa

EVOLUTIONARY LEAP

Move over Springboks and Wallabies — here come the springhasies

Move over Springboks and Wallabies — here come the springhasies
South Africa’s springhares look similar to wallabies and kangaroos but they also have a ‘secret weapon’. Their long hind legs and extra-thick tendons help them to hop very fast and change direction rapidly to avoid pursuing predators – and a new scientific study suggests that they have developed a significant ‘evolutionary jump’ on Australia’s wallabies and kangaroos. (Photo: Edward Snelling and Amy Cheu, basiliskos.com)

Springhares have an added advantage or ‘something of a secret weapon’, an anatomical study has revealed.

South Africa’s world-beating rugby Springboks and Australia’s Wallabies have been matched quite evenly in umpteen games over the past eight decades – though the records show that the Boks ultimately came out tops by winning 48 of the 88 big clashes since 1933.

But if there were to be a World Cup for Hopping in the animal world, South Africa’s smaller and lesser-known springhares (or springhase), would undoubtedly thump Australia’s bigger and better-known kangaroos and wallabies in several departments – if the contest was judged relative to their body size.

South Africa’s springhares look similar to wallabies and kangaroos, but they also have a ‘secret weapon’. Their long hind legs and extra-thick tendons help them to hop very fast and change direction rapidly to avoid pursuing predators – and a new scientific study suggests that they have developed a significant ‘evolutionary jump’ on Australia’s wallabies and kangaroos. (Photo: Flickr.com)

This has emerged from a new anatomical study by a team of scientists from South Africa and the US, who analysed the musculature and tendon size of the two African and Australian hopping groups.

(Just to keep things a bit neutral for Wallaby fans, it may be worth mentioning that one of the SA scientists was born in Australia and lived there most of his life.)

They note at the outset that springhares (which weigh in at around 3kg), are considerably smaller than most wallabies and kangaroos (which can weigh in at up to 10kg and 70kg respectively), yet the latest study published in the Journal of Anatomy suggests that kilogram for kilogram, the smaller South African hoppers have developed some significant evolutionary advantages while dodging Africa’s more fearsome range of predators – including cheetahs.

While both groups move on two legs rather than running on all fours, springhares give birth to live babies that have to start hopping almost immediately, while Australia’s marsupials give birth to undeveloped joeys (babies not linked to the mother by a placenta and which shelter in belly-mounted pouches for the first part of their lives).

The researchers, from the universities of Pretoria, Witwatersrand, Harvard and Idaho, record that the two hopping groups last shared a common ancestor about 160 million years ago, but over time, their paths have evolved to give springhares at least one significant advantage in the form of a very thick and powerful plantaris tendon on their hindquarters.

Ned Snelling. (Photo supplied)

It is this disproportionately thick plantaris tendon which provides springhares with an added advantage or “something of a secret weapon”, says Ned Snelling, a senior lecturer in the Department of Anatomy and Physiology at the University of Pretoria’s (UP) Faculty of Veterinary Science, who moved from Australia to South Africa five years ago.

He uses the analogy of a thick rubber band versus a thin rubber band to illustrate the advantage gained by springhares to hop, skip and jump very fast to outpace and outmanoeuvre predators.

“If you pull on a thin elastic cord, much of the force is lost in the stretch, but if you pull on a thick elastic cord, more force is transferred to the other end.”

The relatively thicker tendon structures in springhares mean that forces can be transferred more rapidly from the muscle to the skeletal attachment points in the feet, favouring speed and acceleration performance.

“So, in the battle of the hoppers, it’s South Africa 1 and Australia 0,” the Australian-born scientist acknowledged ruefully.  

In short, Snelling and his co-authors suggest that in relative terms, springhares can jump faster and further, and also accelerate more rapidly, in comparison to larger marsupials from Australia – though they have not been able to mathematically quantify the magnitude of that advantage.

Image credit: Edward Snelling and Amy Cheu, basiliskos.com.

Snelling says it is possible to quantify this further by training South African springhares to hop on a “force plate or treadmill”.

Unlikely as that may sound, Australian scientists did just that some years ago, when they trained several kangaroos and wallabies to hop long distances on treadmills to better understand the relationship between hopping speed and energy-use in comparison to four-legged animals.

These studies revealed that kangaroos and wallabies are extremely energy-efficient when hopping over long distances.

So, while the Aussie hoppers might have lost out on the fast-jumping swing, they appear to have gained other advantages on the stamina roundabout because it’s likely that they can hop over longer distances using relatively less energy than our boere-hasies (farm hares). DM

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