One of my favorite things about science is that it changes as we do more and smarter research using better and more advanced tools. The study of science is not the pursuit of the answer that we think we should get or the result that tells us what we want to hear. To study science is to follow the evidence even if it upends what we previously thought was true. Remember when Pluto was a planet?
The latest science news to challenge our long standing knowledge comes from the journal Current Biology and centers on the giraffe. Scientists have always considered all of giraffes, which are only found in the wild across sub-Saharan Africa, as one species. In an effort to determine whether the different subspecies of giraffe could thrive if forced to live together for future preservation efforts, a group of biologists and geneticists from the Senckenberg Biodiversity and Climate Research Center in Frankfurt and the Giraffe Conservation Foundation in Namibia tested the DNA of ~200 giraffes from across Africa.
However, instead of identifying the minor differences expected among various subspecies, the researchers found significant genetic mutations that were present in some giraffes but not others, a key indicator that they were dealing with different species. Some of the differences they discovered were as large or larger than those between brown bears and polar bears.
Another key aspect of what links two animals in the same species is their ability to cross-breed with one another. The researchers determined that the four different species of giraffe likely evolved into distinct species by not sharing their genetic material over the past 1.5 million years. That’s still extremely recent by evolutionary standards, but given that these giraffes are all found on the same continent, that’s pretty impressive. In other words, Africa is so expansive that different subsets of giraffe were able to live in near isolation from one another for over a million years. Giraffes are known to travel long distances for food because they need to eat hundreds of pounds of leaves every week.
What Are the Four Giraffe Species?
Giraffes are now classified into four species: the southern giraffe, the northern giraffe, the Masai giraffe, and the reticulated giraffe.
The Maasai giraffe, a former subspecies that has now been promoted to its own species, have darker, jagged spots and are among the largest. They share a name with the Maasai people who have a rich cultural history of a semi-nomadic lifestyle spanning across southern Kenya and northern Tanzania.
The reticulated giraffe, one of two kinds of giraffes most commonly seen in zoos, is also known as the Somali giraffe. The word “reticulated” suggests being marked by a network of interlacing lines and reflects the animal’s larger spots, that are usually deeper in color and that appear outlined by thin white lines.
Why Did the Evolutionary Split Happen?
Understanding why the giraffe evolved relatively recently into four different species will be the focus of the researcher’s next study. Such an evolution could have occurred due to a need for the giraffes to adapt to different environments or to different diets specific to their various locations.
How Did We Mistake Four Species for One?
Giraffes stand as the tallest mammals at 14 to 19 feet tall and 1,750 to 2,800 pounds. Even the giraffe’s tongue is ~21 inches long! Despite their size, we have missed the multiple species that were right in front of us.
The four species were likely mistaken for one species thanks to a lack of studies focused on giraffes. Giraffes aren’t often hunted for either bushmeat or for any horns or tusks like other African animals. They aren’t a threat to humans through physical aggression or through the spread of disease. They don’t even invade food supplies otherwise intended for livestock. These gentle and harmless neighbors of ours have thus been overlooked when it comes to research.
This new finding will likely change that, however. Although giraffe numbers have declined by over 40% in the last decade, giraffe populations were previously not considered to be at risk when all ~90,000 existing giraffes were thought to be a single species. However, the new species identifications finds that there are < 9,000 reticulated giraffes and < 5,000 northern giraffes. The status of at least these two species will likely change and inspire more dedicated conservation efforts.
So what else are giraffes hiding? No two giraffes have the same pattern and we clearly have a lot to learn about these unique animals. Who knows what additional secrets these new studies will reveal!
Until next time, this is Sabrina Stierwalt with Everyday Einstein’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Everyday Einstein on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com.
Image courtesy of Shutterstock.
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