Remember that vacation you took when you were with your squad? They looked good, you looked good, the weather was perfect and the selfies were on fleek. Everyone has moments they remember fondly and wish they could go back to. And, like everyone else, paleoanthropologists wish they could go back in time, too…Just a couple of million years more!
As a species, we humans spend nearly as much effort looking behind us as we do in front of us. From an early age, we are taught the history of our communities, our countries and even, sometimes, our evolutionary history. But, our fascination with the past is not limited to education, using #Takemeback and other social trends, we idolize the thrill of hopping into another era. Why do we focus so much on things of the past? Past experience lends us insight into what may happen next. But how do we learn when there is nothing to collect or read?
Building The Past
Paleoanthropologists have always been curious about where and how humanity all began. They strive to piece together how we, as a species, metamorphosed from small, hairy, arboreal creatures into large, hairless, gangly bipeds. While paleoanthropologists are able to use hominid fossil remains, to understand the past they can only do so to a certain extent. Hominid fossil material typically makes up less than 1% of all material discovered in at a site. Additionally, fossils will only show morphological characteristics. As a result, it becomes nearly impossible to exclusively use hominid material to research and understand why we as a species evolved. So, in order to better understand and answer questions of our evolutionary lineage, paleoanthropologists often use faunal material in addition to hominid fossil material. By doing this, paleoanthropologists are able to recreate the environment and landscape our early ancestors were living in, allowing them to better understand how certain adaptive traits, such as bipedalism, have emerged and why.
Recreating The Past
A tenet of Darwin’s natural selection states that if an organism is unsuited to its environment, it will reduce its overall reproductive fitness, eventually decreasing its chance to pass on its genetic material and vice versa. When observing hominin sites, paleoanthropologists often pull from Darwin’s concept of natural selection in order to create hypotheses about certain adaptations found in fossil fauna that could be related to the paleolandscape. These hypotheses are based on comparative studies built from extant living fauna in similar environments, to the fossil fauna. One such hypothesis is the savanna hypothesis. The savanna hypothesis states that extinct fauna will show a gradual increase towards adaptations for more arid and open environments in certain areas after the late Miocene (11.6-5.3 MYA). These adaptations can be seen in the form of speed and endurance.
Faunal reconstructions are incredibly common and have been made for many different sites, including the Omo, Sterkfontein, and Swartkrans. Within the Omo site region, for example, a great deal of faunal material was recovered spanning a timeline from 4-1 MYA. The material discovered, including both faunal and hominin specimens, showed clear indications of a gradual shift to a more arid/open environment (Savanna Hypothesis for the win!). Looking at the lower stratas high amounts of Tragelaphini and some species of Reduncinae are seen. These are antelope commonly seen in woodland environments. However in the upper stratas, a shift towards more digitigrade and hypsodonty mammal species like Elephantidae and Hipparion were found. Also known as Elephants and Hippos, Elephantidae and Hipparion are linked to more open environments. Even the hominid evidence suggests a gradual shift of woodlands into open grasslands in the Omo region. In lower strata Au. afarensis was found, which was thought to have inhabited a more woodlandesque environment. But, when moving up in the strata evidence of P. boisei and Homo were discovered, both of whom indicate adaptations towards a more open environment. Evidence like this helps paleoanthropologists to better define why certain adaptations came to be. So, while paleoanthropologists can’t actually #Takemeback, they can however #buildthepast.