In 2015, a team of conservation biologists were conducting regular surveys in Uganda’s Murchison Falls National Park when they came across an adult Nubian giraffe that didn't quite fit a typical giraffe's attributes. It had the characteristically long neck of a giraffe paired with short, stocky legs—instead of long, lanky legs ones, reports Annie Roth for the New York Times.
The giraffe, named Gimli, only reached a height of 9 feet, 4 inches tall—several feet shorter than the average adult, which grows to about 16 feet. The team was in "disbelief," Michael Brown, a conservation scientist with the Giraffe Conservation Foundation and the Smithsonian Conservation Biology Institute, tells the Times.
Three years after this puzzling observation, scientists spotted an 8.5-foot-tall, Angolan giraffe on a private farm in Namibia. The team named him Nigel, reports the Times.
Using photogrammetry, a measurement technique that uses a laser to measure distances, the scientists found that Gimli and Nigel had shorter metacarpals and radial measurements, which are the bones below and above their knees respectively, reports Rachael Funnell for IFLScience.
Based on their measurements, the team came to the conclusion that dwarfism was the most likely explanation for their different body sizes and proportions.
"While the Namibian farmer had spotted Nigel regularly over the years, it was only after our observations that he realized that Nigel was not a juvenile but a fully grown male giraffe," co-author Emma Wells, a researcher for the Giraffe Conservation Foundation. "It is mainly in comparison to other giraffe that his difference in stature becomes obvious."
According to a statement from the Giraffe Conservation Foundation, this is the first time that dwarfism has been documented in captive or wild giraffes. The scientists published their findings in December in the journal BMC Research Notes.
Dwarfism, also known as skeletal dysplasia, is a genetic condition that can affect bone and cartilage growth, which can lead to disproportionately sized arms, legs, head or abdomen, according to the Cleveland Clinic. The condition has been well-documented in people, and it's also known to occur in dogs, cows and pigs, reports the Times.
"Instances of wild animals with these types of skeletal dysplasias are extraordinarily rare," Brown says in the statement. "It’s another interesting wrinkle in the unique story of giraffe in these diverse ecosystems."
How these two giraffes ended up with dwarfism is still hazy. Random mutations in the genetic code can cause dwarfism, but it can also be linked to low genetic diversity or inbreeding, reports the Times.
"It’s worth noting that the Murchison Falls National Park giraffe population in Uganda experienced a significant population bottleneck in the late 1980s as a result of civil unrest and poaching," Brown tells IFLScience. "The population has rebounded remarkably since then with current estimates of over 1,500 [giraffes], although it’s unclear if there are any lingering impacts of the earlier population bottleneck."
The scientists plan to monitor Gimli and Nigel over the course of their lives to see if their dwarfism affects their behavior and social statuses, according to the statement.