Purr

The oldest-known animal drawing in the world is a 45,500-year-old depiction of a hairy, warty pig on a cave wall in Indonesia, a new study finds.

The mulberry colored painting, drawn with the red mineral ochre, shows the profile of what is likely a Sulawesi warty pig (Sus celebensis), a wild stubby-legged beast with facial warts that can weigh up to nearly 190 pounds (85 kilograms). These pigs "are still found there today, although in ever-dwindling numbers," said study co-lead researcher Adam Brumm, a professor of archaeology at Griffith University's Australian Research Centre for Human Evolution.

The finding provides more evidence that ancient Indonesia was a hot spot for rock art, and that "the first rock art traditions probably did not arise in ice age Europe as long supposed," Brumm told Live Science in an email.

Related: Photos: Ancient rock art of Southern Africa

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In December 2017, Brumm and his colleagues found at least three warty pig drawings in Leang Tedongnge Cave, on Sulawesi, an Indonesian island that's slightly larger than Florida. This cave was in a small valley now inhabited by Bugis farmers, an enthic group in Indonesia. "There are no roads to this valley; getting there from the adjacent lowlands requires an arduous trek along a forest path that leads up into the limestone hills and ends at a narrow cave passage — this is the only entrance to the valley," Brumm said.

So, despite the valley's proximity to the large city of Makassar, "according to the people who live in this valley, no Westerners had ever set foot in the place before," said Brumm, who worked with an international team from Australia and Indonesia on the study, published online Wednesday (Jan. 13) in the journal Science Advances.

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A very hairy, warty pig that dates to at least 45,500 years ago was found in an Indonesian cave.
A very hairy, warty pig that dates to at least 45,500 years ago was found in an Indonesian cave.(Image credit: Maxime Aubert)
The rock art panel studied at Leang Tedongnge Cave.
The rock art panel studied at Leang Tedongnge Cave.(Image credit: AA Oktaviana)
A digitally enhanced view of the three or four pigs at Leang Tedongnge Cave.
A digitally enhanced view of the three or four pigs at Leang Tedongnge Cave.(Image credit: AA Oktaviana)
This big warty pig has a tiny tail.
A researcher points to the warty pig with a tiny tail.(Image credit: AA Oktaviana)
A researcher points to the other warty pigs on the rock panel at Leang Tedongnge Cave.
A researcher points to the other warty pigs on the rock panel at Leang Tedongnge Cave.(Image credit: AA Oktaviana)
The oldest known animal painting is this pig in Leang Tedongnge Cave in Indonesia.
The oldest known animal painting is this warty pig in Leang Tedongnge Cave in Indonesia.(Image credit: AA Oktaviana)
The outside view of Leang Tedongnge Cave.
The outside view of Leang Tedongnge Cave.(Image credit: AA Oktaviana)
The mouth of Leang Tedongnge Cave.
The mouth of Leang Tedongnge Cave.(Image credit: AA Oktaviana)
This pig, as well as the others, indicate that Indonesia was a hot spot for rock art during the Pleistocene epoch.
This pig, as well as the others, indicate that Indonesia was a hot spot for rock art during the Pleistocene epoch.(Image credit: AA Oktaviana)
This digitally enhanced close-up image shows the warts on the pig dating to at least 45,500 years ago.
This digitally enhanced close-up image shows the warts on the pig dating to at least 45,500 years ago.(Image credit: AA Oktaviana)
Digital tracings of the rock art at Leang Tedongnge Cave.
Digital tracings of the rock art at Leang Tedongnge Cave.(Image credit: AA Oktaviana)
The second pig at Leang Tedongnge Cave measured 4.1 by 1.7 feet (125 by 53 cm).
The second pig at Leang Tedongnge Cave measured 4.1 by 1.7 feet (125 by 53 cm).(Image credit: AA Oktaviana)
Another warty pig at Leang Tedongnge Cave measuring 4.5 by 2.3 feet (138 by 71 cm).
Another warty pig at Leang Tedongnge Cave measuring 4.5 by 2.3 feet (138 by 71 cm).(Image credit: Basran Burhan)
Notice the two handprint by the large pig (left) and the two or three other pigs (right) on the panel.
Notice the two handprint by the large pig (left) and the two or three other pigs (right) on the panel.(Image credit: Basran Burhan)
Pigging out
Of the few pig drawings in the limestone cave, the most well-preserved one is the oldest. It shows a large pig — measuring about 4.5 by 1.8 feet (136 by 54 centimeters), with the outlines of two human hands painted above its rump. The hairy, tiny-tailed porker faces two or three other pigs, which are less well-preserved and appear to be having some kind of social interaction with the giant pig.

In a nearby cave, called Leang Balangajia 1, the team spotted an even larger painted pig on the ceiling, measuring about 6.1 by 3.6 feet (187 by 110 cm), with four stenciled hands on it. That cave chamber has at least two other animal paintings, but they are too damaged to decipher, the researchers said. A few anatomical clues hint that the rock art in both caves depicts adult male pigs — for instance, they're painted with impressive facial warts, which are larger in adult males than in females.

So, why were pigs popular subjects for the caves' artists?

Sulawesi warty pigs are unique to that island — they evolved there in isolation hundreds of thousands of years ago, Brumm said. Archaeological evidence suggests that humans hunted and even domesticated these pigs. "So, it seems clear that early humans interacted closely with this pig on various levels for a very long period of time," Brumm said. "In fact, the ice age artists of Sulawesi almost seem to have been obsessed with warty pigs, which is perhaps not surprising given their economic importance."

One new baby is a handful — but what about two or more? One in 30 parents have their hands full with twins, and nearly one in 10,000 juggle triplets or more, according to U.S. data from the Centers for Disease Control and Prevention.

But how unusual is humans' ability to bear multiple young at once, and how often do other mammals have twins, triplets and quadruplets?

In many animals, multiple babies are the norm rather than the exception. For example, the average dog gives birth to five puppies in a litter, according to a 2011 study published in the journal Theriogenology. So, what's the difference between a litter and twins? "It really just comes down to number," said Charles Long, a reproductive physiologist at Texas A&M University. Whereas a set of twins is by definition two babies, litter-bearing animals almost always have more.

Related: Why pregnancy really lasts 9 months

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A female animal has a litter when she releases multiple eggs. When fertilized, these eggs produce multiple embryos. (Identical twins are the exception — but we'll get to that later.) When a woman releases two eggs, we call the resulting offspring fraternal or non-identical twins. (Three eggs results in fraternal triplets, four in fraternal quadruplets. You get the picture.) Whether they're littermates or fraternal twins, these siblings share about half of their DNA — the same as any other sibling pair.

Litter-bearing animals tend to give birth to more than three babies, on average, Long said. But the difference between litters and twins ends there. Technically, there's no difference between a litter of five and a set of fraternal quintuplets — aside from the fact that human quintuplets are exceptionally rare. In 2017, the Centers for Disease Control and Prevention reported only 49 quintuplet and higher order births out of 3,855,500 total births.

On the other hand, some animals rarely give birth to litters, and instead nearly always bear two young with each pregnancy. In these animals, two babies born at the same time are called twins, not littermates. However, these are usually fraternal, not identical twins. Sheep, goats, and deer all regularly give birth to fraternal twins, Long said.

But what about identical twins?

These genetically identical siblings form when a single fertilized egg splits in two. They're rare in humans: about three to four in 1,000 human births result in identical twins, according to the U.S. National Library of Medicine. And as far as scientists can tell, they’re less common in other animals. Veterinarians have identified identical puppies only once, in 2016. In that rare instance, a veterinarian performing a C-section on an Irish wolfhound happened to notice that two of the puppies shared a placenta. A genetic test confirmed that the two puppies shared all of their DNA. But scientists usually aren’t on the lookout for identical twins in other animals, which may be why they appear so uncommon.

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In one animal, identical siblings are the rule, not a rarity. Armadillos always give birth to identical quadruplets. In other words, female armadillos ovulate one egg that subsequently splits into four once fertilized. Scientists aren't sure why this happens, or why it's unique to armadillos, Long said. One possible explanation: having identical quadruplets prevents inbreeding. Armadillo siblings can't possibly mate with one another, so they're forced to venture outside of their underground burrows to find mates.

And other animals may give birth to identical twins at higher rates than humans realize. "If a sheep has twin males or twin females, we don't go and test them to see if they're identical," Long said. The uncanny resemblance shared by identical twins isn't a helpful clue, he added. "You know, sheep look alike."

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Sailfish (Istiophorus) are a group of fish that scientists often consider to be the fastest fish in the ocean, with a reported top speed of more than 68 mph (110 km/h), according to the National Oceanic and Atmospheric Administration(opens in new tab) (NOAA). However, some experts believe these large fish are actually much slower. Paolo Domenici, a biologist at the Italian National Research Council’s Institute of Biophysics (IBF), has doubts about sailfish and other marine animals swimming over 62 mph (100 km/h). According to Domenici, the widely cited sailfish top speed comes from a Country Life magazine article published in 1941, which isn't a scientific journal, making the data questionable.

"As of now, there isn't really a very clear measure of the fastest speed in potentially fast fish," Domenici told Live Science. He and his colleagues used tags and videos to measure sailfish tail-beat frequencies — the fish equivalent of stride lengths — to calculate how fast they may be able to travel. "When we did that we ended up having at most something around 8 to 10 meters per second [18 to 22 mph, or 29 to 36 km/h], not much higher than that," he said. Domenici co-authored a 2016 study published in the journal Biology Open(opens in new tab) that estimated the maximum swimming speed for sailfish is only about 19 mph (30 km/h).

Related: Sailfish stealthily slash prey with bills(opens in new tab)

Swordfish: 22 to 62 mph (36 to 100 km/h)
A photo of a swordfish swimming above sand in shallow water.

A swordfish swimming in shallow water. (Image credit: SVITO-Time/Shutterstock.com)
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Swordfish (Xiphias gladius) are also contenders for the title of fastest swimming animal, with an estimated top speed of over 62 mph (100 km/h). However, this figure comes from Russian research translated into English and published in the early 1960s. The descriptions for how the swim speed was measured are not very clear or reliable, according to Domenici.

A 2007 study published in the Journal of the Royal Society Interface(opens in new tab) suggests that over 62 mph may be well beyond the physical limits of any fish or cetacean (porpoises, dolphins and whales). The researchers found that bubbles created by the animals while swimming can collapse on their fins and may cause damage if they travel faster than 10 to 15 meters per second, or 22 to 34 mph (36 to 54 km/h). In other words, these speeds may be about as fast as animals can swim in water because they would injure themselves by traveling faster.

Domenici thinks swordfish could still be the fastest fish in the ocean, despite likely not being able to travel much faster than 22 mph. The fish use their swords and large, streamlined bodies to reduce drag and streak through the water. Swordfish also secrete oil from pores on their heads to create a lubricating oil layer that may further reduce drag and increase their swimming efficiency, according to a 2016 study published in the Journal of Experimental Biology(opens in new tab).

Dall's porpoise: 34 mph (54 km/h)
A photo of Dall's porpoises swimming at the surface off Alaska.

Dall's porpoises swimming at the surface off Alaska. (Image credit: davidhoffmann photography/Shutterstock.com)
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Dall's porpoises (Phocoenoides dalli) speed through the water at up to 34 mph (54 km/h), according to Whale and Dolphin Conservation(opens in new tab) (WDC), a wildlife charity that focuses on cetaceans. Most porpoises are shy and avoid boats, but Dall's porpoises seek them out to ride their bow waves, The bow wave is created at the front of a boat and pushes animals that are riding the wave forward, which can help them swim faster than they would normally, according to Domenici.

Dall's porpoises live in the cold waters of the North Pacific Ocean, according to NOAA. Porpoises(opens in new tab) are a separate group of marine mammals to dolphins, which have longer bodies and elongated beaks, or mouths. Orcas(opens in new tab) (Orcinus orca), the largest members of the dolphin family, may also be able to reach speeds of 34 mph in front of a boat. This is the same speed as the upper limit in the 2007 study mentioned above, before animals may start damaging themselves.

Related: Two-headed conjoined porpoises hauled up from the deep(opens in new tab)

FASTEST ANIMALS IN THE SKY
Brazilian free-tailed bat: 100 mph (160 km/h)
A photo of a Brazilian free-tailed bat (Tadarida brasiliensis) on the floor in Brazil.

A Brazilian free-tailed bat (Tadarida brasiliensis) in Mato Grosso, Brazil. (Image credit: imageBROKER/GTW via Getty Images)
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The fastest-flying animal on record is not a bird but a mammal. A 2016 study published in the journal Royal Society Open Science(opens in new tab) clocked Brazilian free-tailed bats (Tadarida brasiliensis) flying up to 44.5 meters per second, or 100 mph (160 km/h). The study tracked female bats that weighed around just 0.4 ounce (11 to 12 grams).

Some experts believe that white-throated needletails (Hirundapus caudacutus), members of the swift bird family, can fly even faster, at 105 mph (169 km/h). But this has never been proven scientifically, according to the National Audubon Society(opens in new tab), a nonprofit conservation organization that focuses on birds and their habitat.

Brazilian free-tailed bats aren't just found in Brazil, as their name suggests. They range from Argentina and Chile in South America, through Central America and into the United States, including Oregon and Ohio, according to the International Union for Conservation of Nature(opens in new tab) (IUCN). The tiny bats tend to roost together in large numbers at only a few roost sites, which makes them vulnerable to human disturbance and habitat destruction, according to the Texas Parks and Wildlife Department(opens in new tab).

The fastest animals use speed to survive and thrive in the wild, swiftly chasing down prey or escaping from predators. These record-breaking speedsters are found all over the world and across the animal kingdom, whether they are running on land, swimming in water or flying in the sky. Below are nine of the fastest animals alive today.

Although they would smoke their human counterparts, wild animals don't take part in any Olympic races, so scientists often have to venture into the creatures' natural habitats to find out how fast they can move. And because animals don't necessarily travel at their fastest possible speed when humans happen to be measuring them, many of the speeds on this list are estimates — the animals could be even faster.

FASTEST ANIMALS ON LAND
Ostrich: 43 mph (70 km/h)
A photo of a male ostrich running in grass in the Masai Mara Game Reserve in Kenya

A male ostrich running in the Masai Mara Game Reserve in Kenya (Image credit: Mary Ann McDonald via Getty Images)
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Ostriches(opens in new tab) (Struthio camelus) are the largest birds on Earth(opens in new tab) and the fastest birds on the ground, but they don't fly. They use their long, powerful legs to run up to 43 mph (70 km/h) in short bursts, according to the San Diego Zoo(opens in new tab). Ostriches grow up to 9 feet (2.7 meters) tall and can cover 10 to 16 feet (3 to 5 m) in a single stride. These giant birds use their quickness to escape danger, including predators such as lions(opens in new tab) (Panthera leo).

Ostriches live in semi-arid plains and woodlands in Africa, including countries such as Mauritania and Senegal in western Africa; Somalia and Tanzania in eastern Africa; and Zimbabwe and South Africa in southern Africa, according to the African Wildlife Foundation(opens in new tab).

Related: Extinct 11-foot 'super-ostrich' was as massive as a polar bear(opens in new tab)

Pronghorn: 60 mph (97 km/h)
A photo of a pronghorn buck running through a prairie in Yellowstone National Park.

A pronghorn buck running in Yellowstone National Park. (Image credit: jared lloyd via Getty Images)
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Pronghorns (Antilocapra americana) are small, hoofed mammals from North America that can hit top speeds of up to 60 mph (97 km/h), according to Barnyards & Backyards(opens in new tab), a magazine partnered with the University of Wyoming. This means pronghorns are the second fastest animal on land.

There aren't any predators that can reach close to that speed in North America today, but these swift antelope relatives evolved alongside now-extinct American cheetahs, which the pronghorns needed to outrun in order to survive, according to the U.S. Fish & Wildlife Service(opens in new tab). Pronghorns in Wyoming may undertake migrations that can span 300 miles (483 km) in search of food, according to the National Wildlife Federation(opens in new tab).

Cheetah: 70 mph (112 km/h)
A cheetah runs in Serengeti National Park.

A cheetah runs in Serengeti National Park. (Image credit: Winfried Wisniewski via Getty Images)
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In the animal Olympics, cheetahs(opens in new tab) (Acinonyx jubatus) would dominate the sprinter races. These big cats are the fastest land animals and are capable of running at a top speed of 60 to 70 mph (96 to 112 km/h). One cheetah from the Cincinnati Zoo named Sarah was recorded running the 100-meter sprint in 5.95 seconds, Live Science previously reported(opens in new tab). The fastest human ever, Olympic runner Usain Bolt, holds the world record for running the same distance in 9.58 seconds. During this sprint in 2009, he reached a top speed of 27.8 mph (44.7 km/h), according to the Olympics(opens in new tab) website.

Cheetahs live in northern, eastern and southern Africa, with a small population in Iran in Asia. They have long, slender bodies and powerful legs to help them reach their top speeds so they can chase down speedy prey, such as gazelles(opens in new tab).

Related: The secret to cheetahs' speedy stride found(opens in new tab)