Don’t Forget to Bring your Trowel! The 101 on Paleoanthropology

Defined as “the study of ancient humans,” paleoanthropology is a branch of anthropology which strives to reconstruct all aspects of human evolution (25). A multidisciplinary field, it combines disciplines such as archaeology, anthropology, paleontology, geology, as well as many others to observe the anatomy, behavior, and ecology across the hominin lineage. By better understanding the hominin lineage, paleoanthropologists attempt to discover how early hominins lived and “how” and “why” certain species evolved in anatomically modern humans, or died out.

23251359883_1c355732ef_b

So how do paleoanthropologists begin to answer these questions? Paleoanthropologists use early archaeological, hominin and paleoenvironment evidence, which allows them to begin the process of reconstructing our ancient past. Evidence often includes fossilized bone from both hominins and other animals, lithics, plant and animal matter, footprints, evidence of hearths, butchery marks on animal bones and art (36). https://media.giphy.com/media/xUPGcmF2iGsTGEFVL2/giphy.gifUsing these materials, researchers can then establish hypothesis which can begin to explain the physical and behavioral makeup of early hominins and how it has altered across a spatial and temporal timescale. Going back to our graduate students, say for example one of them discovers an Acheulean bifaced tool along with an extremely “primitive” fossilized hominin hand.

Acheulean biface

Australopithecus Sediba

 

 

 

 

 

 

 

 

Assuming that this graduate student has gained an adequate knowledge of hominin functional morphology, they might note that the dexterity required to create an Acheulean biface surpasses the dexterity found in the fossilized hand. As a result, the graduate student is faced with four potential hypotheses: 1) the tool was not created by the hand of the “primitive” hominin 2) the tool was created by a different hominin species living at the same time 3) the deposit in which the tool and the hominin were found was mixed in with another deposit layer, or 4) the tool was indeed created by the hand of that hominin and all our previous understanding of hand morphology is flawed.

https://media.giphy.com/media/11BAxHG7paxJcI/giphy.gif

To locate fossils, researchers typically look for areas which might potentially hold hominin fossils. This can be anything from sediments of the right time period being exposed by natural erosion to educated guesses based on the locations of previously discovered fossil specimens. Fossils are typically discovered in two different locales depending on the region of Africa they are located in. East African fossil specimens are typically located throughout rift valleys whereas in South Africa fossil specimens are mostly found in cave sites. African Rift valleys are caused when portions of earth’s crusts have been pulled apart due to the movement of tectonic plates (40)

Olduvai Gorge in Tanzania, East Africa

Sterkfontein near Johannesburg, South Africa

This then results in deep valley/trench like formations surrounded by large mountain ranges   Fossils, if found in East Africa, will usually be exposed along the sides and floors of the rift valleys due to rivers and streams eroding deep into the sediment layers. In South Africa, fossils are mainly found in caves. This is due to South Africa having large limestone deposits. Since limestone is extremely porous, as rainwater runs through a limestone crack it erodes surrounding limestone, eventually expanding into caves and tunnels. At any sort of cave opening, soil will be washed in from the surface, allowing for hominin remains to be deposited there. Hominin fossils in South Africa are typically found when miners blast the caves in order to attain the limestone or other mineral resources. The famed Taung Child, for example, was discovered at the Buxton limestone quarry in the Northwestern Province of South Africa following a mining blast.

Even after being blown up, it still took Raymond Dart 3 months and a pair of sharp knitting needles to painstakingly uncover Taung Child from the attached limestone.

While hominin fossils are located within caves there is weak evidence which suggests that early hominins used caves as habitation sites (40). Paleoanthropologists actually believe that the majority of hominin fossils found in caves were brought in by leopards, hyenas or bone collecting animals such as the porcupine (37).

https://media.giphy.com/media/3oEhmOCVVhTXA7x3IA/giphy.gif

A lean mean bone crushing machine!

As an apex predator in today’s world, it is often hard to imagine any of our ancestors becoming prey. However, many of our early ancestors were physically, mentally and presumably socially different than ourselves, making them more susceptible to predation. A famous juvenile Paranthropus robustus skull cap (SK-54) from Swartkrans was discovered to have two 6mm puncture wounds-wounds that when paired with the lower jaw of an African leopard match perfectly (33&39). Additionally, there have been some claims to evidence suggesting that Taung Child was killed by a large predatory bird (5&22).

Taung Child (Australopithecus africanus)

Taung Child-Australopithecus africanus

Paleoanthropologists fervently strive to discover fossils and artifacts such as SK-54, as they are a physical evidentiary timestamp of a particular event. Unfortunately, fossils like SK-54 are quite rare and often it is up to paleoanthropologists to hypothesize what occurred over the last 4 million years.  By probing into the past, researchers, like our graduate students, can begin to ask some of the broader questions surrounding our evolutionary history,  and perhaps, glean important information into who we are.

 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.