The importance of primates for evolutionary theory can hardly be overstated. The applications of the traits – the foundation of the distinction between primates and other organisms – are widespread and profound in anthropology as well as basic biology. Primates are a diverse class of organisms that share a suite of derived traits (characteristics primates inherited from their common primate ancestor) that separates them from other organisms (Ryan). For instance, primates share several inherited primeval traits with other animals from a distant mammalian common ancestor such as having body hair (fur) and being warm-blooded and even more distant terrestrial vertebrate predecessors such as having four limbs and a spinal column (Cartmill). Because of such primate trait diversity, no single feature can be used to separate all primates from other animals, but rather a set of derived and discernable characteristics that all, or at least most, primates share (Ryan).
According to Ryan, the unifying attributes that can be used to describe primates are related to three tendencies common in the primate family: the inherent adaptation for an arboreal lifestyle (Cartmill), significant parental investment (Larsen), and a broad plasticity to dietary choices (Parikh). Firstly and concerning arboreal adaptation, fossil, and genetic evidence suggests that all living primates are a derivative of a common ancestor that lived about 77 million years in a primarily arboreal environment (Larsen; Ryan). Over those years, primates have developed unique combinations of specific arboreal adaptations such as having improved vision for eye-hand coordination. Primates also have a versatile skeletal structure for arboreality such as phalanges that allow for limb dexterity, powerful precision grips, and a strut-acting clavicle that keeps the forelimbs to the sides of the body (Cartmill; Larsen).
Secondly, primates show significant parental investment attribute in which parents provide not only prolonged care to offspring but also do so smartly in a more socially complex environment as a mechanism for the young ones to learn all they need to know (Parikh). Thirdly, all primates exhibit dietary plasticity (Larsen). They eat a highly diverse diet, and their teeth are designed to reflect and handle such adaptive versatility (Ryan). For example, their dental specializations and functional emphases show that premolars and molars are for grinding and chewing while canines and incisors for biting into and slicing food (Larsen). In this regard, primates differ from other animals that have either lost or modified their teeth in the course of their evolutionary history. Other characteristics of primates include larger brain-body ratio, modified claws to nails, pentadactylism, improved vision (forward facing eye, depth perception, binocular, and stereoscopic view), the de-emphasis on smell (olfaction), and increasing behavioral complexity (Ryan).
The ecological milieu in which the primates evolved has not only placed demands on their adaptive behavior and capacity throughout their evolutionary time but has also shaped most of the unique primate attributes we see today (Larsen). The above tendencies together with other traits such as social grouping, omnivorous diet, reduced prognathism, and increased complexity of the cerebral cortex, just to name but a few, are manifest in the behavior, life history, and the anatomical structures of primates in a variety of ways.
Works Cited
Cartmill, Matt. "Rethinking Primate Origins." Science 184.4135 (1974): 436-443. Web. 5 May 2016. <http://science.sciencemag.org/content/184/4135/436>.
Larsen, Clark S. "Chapter 6: Biology in the Present - The Other Living Primates." Our Origins: Discovering Physical Anthropology. 2nd ed. New York: W.W. Norton & Co, 2008. Print.
Parikh, Janaki N. "Shared Trait of Primates." N.p., Web. 5 May 2016. <http://www.lahc.edu/library/documents/parikh/Bio%20Anthro-%20primate%20shared%20traits.pdf>.
Ryan, Tim. "Primate Traits — Humans As Primates." Liberal Arts Outreach. Penn State University, 2016. Web. 5 May 2016. <http://elearning.la.psu.edu/anth/022/lesson_2/lesson-page-2>.
