Big Boned: A Review of the Paranthropus Genus

Figure 1: Paranthropus aethiopicus

 
One of the things humans across several different cultures often times wonder about is where we (humans or individuals) come from.  This is a central question to paleoanthropologists who study human origins.  Through the study of the biological lineages of human ancestry there are several twists and turns in species that have long gone extinct but who may have (or may not have) contributed to who and how we identify Homo sapiens today.  Today's blog post will discuss one genus of potential human ancestors: the Paranthropus genus.

The Paranthropus genus refers to a group of hominid species characterized as having small brains, robust (i.e. large) cranial features who subsisted on an exclusively vegetarian diet.  These species were at one time classified as Australopithecines (and sometimes still are), but because of their unique robust cranial features some scholars believe they should be classified as a separate genus.  If you were to look into them further you will want to be aware of this so you do not miss out on information as not all scholars agree to the Paranthropus designation and therefore still refer to them as Australopithecines.

Figure 2: Paranthropus robustus

 
Paranthropus species are found primarily in the Lake Turkana region of Kenya, although one (Paranthropus robustus) is found in South Africa.  They are all characterized by sharing several cranial features, including postorbial constriction (a narrowing of bone behind the eye sockets, which is common in nonhuman primates), large molar teeth and smaller canines, exaggerated sagittal crests (a boney ridge, or mohawk as I like to refer to it, along the midline of the skull), broad cheeks that flare out, and a flattened/dished face.  Their large cranial features, particularly their molars, made them specifically adapted to eating specialized vegetarian diets that other contemporaneous hominids could not eat.  They subsisted largely on hard nuts, roots, and other vegetative matter that we, modern humans, cannot easily eat raw or without some sort of assistance (e.g. a nut cracker or by cooking the food to soften it).   

There are three known Paranthropus species: Paranthropus aethiopicus (Figure 1), Paranthropus robustus (Figure 2), and Paranthropus boisei (Figure 3).   To the untrained eye there are very few differences that distinguish them from each other, but there are actually very distinct differences that allow one to identify who they are and how they are different.  P. aethiopicus has the smallest brain, largest sagittal crest, and most prognathic (jutting forward) face of the three.  Despite his name P. robustus is not the most robust of all the species, although P. robustus does have some of the heaviest jaws.  Plus, as previously mentioned it is the only species found in South Africa (based on current knowledge).  P. boisei was actually named after the investor who assisted Louis and Mary Leakey discover it, has the largest geographical range, and is considered "hyperrobust" in all of its cranial and facial features. 

Figure 3: Paranthropus boisei

So there you have it.  Some information on the Paranthropus genus, as well as details to help you be able to differentiate them.  If you are interested in learning more about these species please check out this excellent review video.  Also, for those who may be wondering how do these species fit into our human lineage I can only say that we are still trying to figure that completely out.  There are some scholars who believe they are an evolutionary dead end, and others who believe at least one of them added to our gene pool and evolution to produce us as we are today.  As more data is collected and more discoveries made we will hopefully have a more definitive answer about how these species fit into our family tree.

References

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

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