Where does a giraffe get its spots? The question seems simple enough, but the gentle giants’ iconic interlocking spotted coats have puzzled researchers for years. Now, reports Jennifer Leman at ScienceNews, a new study suggests those giraffe splotches are passed down from mother to child, and the spots’ size and shape can have a big impact on whether or not a young giraffe survives.
One of the study’s authors, Penn State biologist Derek Lee, tells Leman that the most common question people ask about giraffes is why the creatures have spots and whether those spots run in the family. Previously, scientists suspected that the spots could be totally random patterns or that perhaps environmental variables led to different sizes and shapes. But no one had really set out for a definitive answer before, Lee notes.
“We didn't have any answers,” he says. “So we used our data to get them.”
Over the course of four years, Lee and his team photographed the coats of 31 sets of mother giraffes and their babies. Using image analysis software, they looked at 11 traits, including size, shape and color, to determine if the animals passed along their spot patterns. Two of those traits—circularity, or how round they were, and softness of the spots’ edges—were strongly linked between parent and child, indicating a hereditary element, the team reports in a paper published in the journal PeerJ.
The study also revealed that the size and shape of spots help determine which baby giraffes make it to adulthood. For that part of the study, the team looked at 258 giraffe calves, photographing them six times a year for four years. That they found is the larger and more irregular the shape of their spots, the more likely the juvenile giraffe was to survive the first months of life.
According to a press release, the bigger spots may act as better camouflage for the wee giraffes, or they could aid in other ways, like providing better body temperature control or serve as visual communication. Fred Bercovitch, executive director of Save the Giraffes, not involved in the study, tells Corinne Purtill at Quartz that giraffes use the spot patterns to recognize one another from a distance, and that if the patterns have a hereditary element it could signal to one another information about family relationships. Either way, a baby giraffe that adults can see more easily has a better chance of being protected from predators.
“They’re not suggesting that spots matter for survival, but that the differences in spots matter for survival,” evolutionary biologist Hopi Hoekstra of Harvard, not involved in the study, tells Leman. “It’s slightly subtle, but I think an important distinction.”
There were some limits to the study. Male giraffes don’t stick around to raise the kids. On the contrary, it’s easy to match a calf with its mother because calves suckle, sometimes for as long as two years. So unfortunately, researchers weren’t able to compare offspring spot patterns to both parents. Lee tells Tik Root at National Geographic that the study is just the beginning of unraveling the mysteries of giraffes.
In fact, he says the research could help in figuring out the genetics and purpose of other mammal coat patterns, which continue to perplex biologists. The genetics of how patterns are formed, however, is complex and the genes that produce them often have multiple purposes.
One thing is for sure: It will take a lot more genetic information and a lot more pictures of cute baby animals to sort it all out.