To Be or Not To Be A Primate? Understanding What It Means To Be a Primate

Top Left (Clockwise): Tarsier, Baboon, Spider Monkey, Orangutan, Human, Lemur 

Believe it or not humans are primates.  So are baboons, aye-ayes, and orangutans.  But tree shrews are not.  There is a great deal of diversity in the species that make up the primate order, and this can and often does create confusion among those just beginning to understand biological anthropology and primatology.  Today’s blog post will cover what it means to be a primate, the different groups within the primate order, and some general primate characteristics shared by all of the species within the order (all the way from the pygmy mouse lemur to gorillas).  ;)

First, it is important to understand what primate means.  The term primate refers to a mammalian order, which is a taxonomic classification that groups like organisms (in this case, mammals) based on specific shared characteristics or traits.  It is a higher level of classification that has broader shared characteristics or traits (compared to genus and species, which are more specific in those shared characteristics and traits).  Within any order there can be suborders, which further refine the organisms within the order grouping.  In the case of primates there are two suborders: Anthropoidea, which includes monkeys, apes, and humans, and Prosimii, which includes lemurs, lorises, & tarsiers.  The distinction between these two suborders relates to the evolutionary changes between the two groups; Anthropoids are considered more evolutionarily advanced (meaning they underwent additional evolutionary changes) as compared to Prosimians (who more closely resemble primate ancestors).  From here there are (obviously) additional characteristics that further define and categorize the various primate species, but for simplicity we are going to stop here.  Note, those interested in learning more are encouraged to peruse other blog posts or take an Introduction to Biological (aka Physical) Anthropology course.

So what specific characteristics define the order primates?  Well, there are several, and as such they are going to be broken down in a bulleted list:

·         Limbs & Locomotion

o   All primates have an erect posture, have the ability to locomote (move) in various ways (be it swinging from trees or walking on land), as well a prehensile (grasping) hands and feet, although that prehensibility does vary greatly within the order.  For example, a chimpanzee can grasp a pencil with its foot, whereas most humans cannot.  Also, all primates have tactile pads on their hands and feet, which allow for sensitive feeling in them (such as what I feel as my fingers click onto the keys of the keyboard), as well as nails, not claws (an adaptation gained from our shared tree dwelling ancestors).

·         Diet & Teeth

o   The majority of primates are omnivorous, meaning they eat plants and meat.  There are a couple of notable exceptions, such as the tarsier (scrolls all the way down), which are largely carnivores, and gorillas (again, scroll to the bottom), who are vegetarians.  To this end primates have generalized dentition, meaning they have teeth for tearing (e.g. incisors and canines) and for crushing or mashing (e.g. premolar and molars).

·         Senses & Brains

o   The majority of primates are diurnal, meaning they are awake during the day, although, again, some are nocturnal, meaning active at night.  These are most often species that fall within the suborder Prosimii.  Primates also have reduced olfaction, meaning our sense of smell is not as strong as other species (which is why there are no drug sniffing humans), but we make up for it in our enhanced vision.  Primates can see more variations in color than most other species, as well as stereoscopically, meaning in three dimensions.  Because we have two forward facing eyes we have a greater field of vision as compared to other species, and our brains have not one but several vision centers that allow for the full processing of the visual information our eyes receive.  Our large brains also allow us to process and think creatively, allowing us to communicate and among various species (e.g. apes and humans) create culture.  Unfortunately, our large brains disable us from leaving our parents early in life, meaning we have a slower maturation period to allow for our brains (and bodies) to fully develop.  This leads to greater infant dependency periods and greater social bonds among individuals and groups, which is why all primates are social creatures by nature.

As you probably already realized that is a lot that defines primates, which is why it is an order classification.  As we narrow down the taxonomic classifications down to the genus and species levels we can refine specifically what makes up specific groups (e.g. the genus Homo versus the genus Pan).  It is interesting to note that we share quite in common with our primate cousins, and this is why we study them, in part to understand what it is to be human.  :)

Bibliography

Jurmain, Robert, Kilgore, Lynn, Trevathan, Wenda, Ciochon, Russell L. Introduction to Physical

Anthropology. Belmont, California: Wadsworth, 2014. Print.

Welsch, R. and L. Vivanco.  2015.  Cultural Anthropology: Asking Questions About Humanity.  Oxford University Press.  

(Image Provided by Common Descent Podcast)