Scientists classify living organisms into hierarchical groups based on shared features and evolutionary relationships. This system helps understand how different species are connected. A common question arises: are humans catarrhines? Exploring the characteristics of this primate group helps position humans accurately within primate classification.
Characteristics of Catarrhines
Catarrhines are a parvorder of primates, often referred to as Old World monkeys and apes, distinguished by several unique physical traits. A defining feature is their narrow nasal septum, resulting in nostrils that point downward or forward. This contrasts with New World monkeys, which have broad noses with widely spaced, sideways-facing nostrils.
Another characteristic is their specific dental formula, 2.1.2.3. Catarrhines generally lack prehensile tails. Many species also exhibit flat fingernails and toenails, and some, like Old World monkeys, have tough sitting pads called ischial callosities. These primates are native to Africa and Asia, inhabiting diverse environments. They tend to be larger than New World counterparts and often show considerable sexual dimorphism.
Humans: Members of the Catarrhine Group
Humans are classified as catarrhines, evidenced by our anatomical features. Our noses have a narrow nasal septum with downward-pointing nostrils, aligning with this primary catarrhine feature. Our dental structure also matches the catarrhine formula of 2.1.2.3. Furthermore, humans, like other catarrhines, do not possess a prehensile tail.
Human classification within the catarrhine group reflects shared ancestry and evolutionary history. While humans have evolved unique traits such as bipedalism and advanced cognitive abilities, these anatomical and dental commonalities firmly place us within this primate parvorder.
Our Place Among Primates
Within the parvorder Catarrhini, two major superfamilies exist: Cercopithecoidea, which comprises the Old World monkeys, and Hominoidea, which includes the apes. Humans belong to the Hominoidea superfamily, placing us firmly within the ape lineage. This means humans share a more recent common ancestor with other apes than with Old World monkeys.
Old World monkeys and apes differ morphologically. Apes, including humans, lack external tails, while most Old World monkeys possess tails. Apes generally have larger, more complex brains relative to their body size. Their skeletal structures also differ, with apes exhibiting broader chests, shoulder joints allowing greater rotation, and a more flexible wrist.
The Hominoidea superfamily divides into two groups: lesser apes (gibbons) and great apes (orangutans, gorillas, chimpanzees, bonobos, and humans). This classification illustrates that while humans are catarrhines and apes, we are also part of the great ape family, highlighting our close evolutionary ties to these large-bodied, tailless primates.