What Are Giraffes Related To? Surprising Facts About Their Kin

Giraffes are instantly recognizable for their towering height and distinctive spotted coats, but their evolutionary connections might not be as obvious. While they share traits with various hoofed mammals, their closest relatives may come as a surprise.

Understanding the giraffe’s family ties offers insight into its evolution and unique adaptations.

Giraffe Family Classification

Giraffes belong to the family Giraffidae, a small group within the order Artiodactyla, which includes even-toed ungulates such as deer, antelope, and cattle. Unlike these more diverse families, Giraffidae consists of only two extant species: the giraffe (Giraffa camelopardalis) and the okapi (Okapia johnstoni). Fossil evidence suggests early giraffids were more diverse, with multiple genera once roaming Eurasia and Africa. Today, only these two species remain.

The evolutionary history of giraffids dates back to the Miocene epoch, approximately 16 million years ago. Early ancestors such as Palaeotragus and Sivatherium displayed a range of body sizes and neck lengths, indicating that the extreme elongation seen in modern giraffes was a gradual adaptation. Genetic and morphological studies suggest giraffes and okapis shared a common ancestor around 11.5 million years ago before evolving along separate paths. Giraffes adapted to open savannas, developing their towering stature, while okapis retained a compact form suited for dense forests.

Taxonomically, giraffes were traditionally classified as a single species with multiple subspecies. However, a 2016 study published in Current Biology proposed dividing them into four distinct species based on genetic divergence: the northern giraffe (Giraffa camelopardalis), the southern giraffe (Giraffa giraffa), the reticulated giraffe (Giraffa reticulata), and the Masai giraffe (Giraffa tippelskirchi). These findings suggest giraffe populations have evolved separately for hundreds of thousands of years, with limited interbreeding. Recognizing multiple species has significant conservation implications, allowing for more targeted strategies to protect genetically distinct populations.

Okapi as a Close Relative

At first glance, the okapi (Okapia johnstoni) appears to have little in common with its towering giraffid cousin. Its compact frame and dark brown coat with white-striped legs more closely resemble a zebra than a giraffe. However, fossil and genetic evidence confirm that the okapi and giraffe diverged from a common ancestor around 11.5 million years ago, adapting to different ecological niches while retaining key giraffid traits.

Despite its shorter neck, the okapi shares structural similarities with giraffes, including skull shape, ossicone structures, and a long, prehensile tongue capable of stripping leaves. This tongue, extending up to 18 inches, mirrors the giraffe’s adaptation for high browsing, though the okapi uses it in the dense understory of the Congo rainforest. Additionally, its limb proportions and gait resemble those of giraffes, moving both front and back legs on one side of the body simultaneously in a pacing motion—a characteristic unique to giraffids.

Ecologically, the okapi’s solitary and elusive nature contrasts with the giraffe’s social and conspicuous lifestyle. Endemic to the Ituri Rainforest of the Democratic Republic of the Congo, it relies on acute hearing and camouflage to evade predators. Large ears detect faint disturbances, while its striped hindquarters break up its silhouette against dappled light, making it nearly invisible to lurking leopards.

Both species are ruminants with complex digestive systems suited for fermenting fibrous plant material, though their diets differ. The okapi consumes a wide range of understory plants, including fruits, ferns, and fungi, many of which are toxic to other herbivores. Meanwhile, giraffes focus on acacia leaves and other high-canopy vegetation, demonstrating how both species have adapted to their respective habitats through divergent evolutionary strategies.

Genetic Discoveries in Giraffe Lineage

Advances in genetic sequencing have reshaped the understanding of giraffe evolution, revealing patterns of divergence previously obscured by outward similarities. While giraffes were long classified as a single species with regional variations, whole-genome analyses have demonstrated significant genetic differentiation among populations. By examining single nucleotide polymorphisms (SNPs) across various giraffe genomes, researchers have identified distinct evolutionary lineages corresponding to geographic distributions, supporting the classification of four genetically distinct species.

Beyond redefining species boundaries, genetic research has provided insight into the adaptations that allowed giraffes to develop their extraordinary physiology. One of the most striking findings involves the gene FGFRL1, which plays a role in cardiovascular and skeletal development. Due to their towering height, giraffes require specialized adaptations to regulate blood pressure. Comparative genomic studies have revealed unique mutations in FGFRL1 that enhance arterial elasticity and strengthen blood vessel walls, preventing complications such as hypertension. These modifications allow giraffes to tolerate extreme fluctuations in blood pressure, particularly when lowering their heads to drink.

Genetic analysis has also shed light on the selective pressures that drove giraffe evolution. Studies examining positively selected genes have identified variations associated with rapid skeletal growth, particularly in pathways involving the HOX gene family, which regulates body patterning during embryonic development. Unlike other large mammals, giraffes exhibit an accelerated yet controlled elongation of cervical vertebrae without compromising structural integrity. Mutations in genes related to bone density and growth factor signaling ensure their long necks remain both lightweight and strong. These adaptations highlight the intricate genetic mechanisms that shaped the giraffe’s unique morphology, distinguishing it from all other ruminants.