Walking Tall: Understanding the Biological Adaptations that Led to Bipedalism

If we look at our hominid (human) ancestors we will see several defining characteristics that differentiate hominids from other primate species.  While early scholars believed it was our large brains that defined humans as humans it was actually the ability to walk bipedally, or the ability to walk on two legs.  This is a feature that is unique to hominids and humans as we are the only species that are able to walk bipedally.  But how exactly did our hominid ancestors adapt the ability to walk on two legs?  Today’s blog post will discuss the morphological (the form and structure of the body) changes that led to bipedal adaptations in hominids and, ultimately, humans.

Figure 1: Pelvic Girdle & Upper Leg Differences Among Three Primate Species

There are several anatomical features that lend themselves to providing organisms the ability to walk on two legs: pelvic, upper leg, spinal column, and cranial changes.  In order for an organism to have the ability to be a biped the pelvis (hips) must change to allow for a wide range of motion in the legs.  If you look at hominids and humans and their ability to move they have a ball and socket joint in both of their hips, which allow for unrestricted motion (as long as the individual has the flexibility to do so).  Quadrupedal primates have limited ranges of motion based on the placement and angle of the hip bones (Figure 1), which leads to some but not full bipedal abilities.  Typically, if quadrupedal primates (or animals, in general) attempt to walk bipedally it is for short periods of time and can also be quite painful.  

Figure 2: Lumbar Curve

In addition, the placement of the pelvic bones allows for the angling of the upper leg bones.  This allows for an upright posture, which is necessary for bipedal locomotion.  The angling of the legs, however, is not the only feature required for upright posture.  A lumbar curve, the curvature of the lower vertebrae/part of the spine, also enable hominids and humans to stand upright (Figure 2).  This is why individuals with degenerative spinal disorders have difficulties walking because the lumbar vertebrae are most often affected, causing a hunching forward that inhibits the upright posture and effective bipedal locomotion.

Figure 3: Foramen Magnum Placement Among Primate Species

Last but not least, cranial changes are also necessary for effective bipedal locomotion.  The foramen magnum is a large hole in the skull where the spinal cord means the skulls, and the placement of the foramen magnum is a determining factor in the locomotion pattern of each species.  A posterior placement causes quadrupedal locomotion, whereas an inferior placement allows for bipedal locomotion because it allows for the upright posture (Figure 3).

These anatomical features first appeared in our hominid ancestors approximately 4 million years ago.  It is unclear as to why our hominid ancestors developed bipedal locomotion as it has its disadvantages (e.g. reduction in speed as compared to quadrupedal species), but it may have also had several advantages.  But this is a topic for a later blog post (stay tuned!)    

Bibliography

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

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

Stein, P.L. & Rowe, B.M. (2014). Introduction to Human Evolution and Prehistory.  United

 States of America: McGraw Hill Education.

Put A Ring On It: A Review of Marriage Patterns & Types

Kinship is a socially defined means that organizes individuals into family units based on descent and marriage.  Kinship and family is a cultural universal and a product of the social nature of humans (and all primates for that matter).  Kinship patterns do vary by culture, and what may be the norm in one culture may be atypical in another.  The topic of kinship is quite broad as it covers a variety of matters related to familial relations (and what is considered non relations).  As such, today’s blog post focuses on a topic of marriage patterns and types. 

In American culture there is one typical and lawful marriage type: monogamy, or the marriage of two individuals to each other and no others.  This definition of monogamy is rather simple, but it does not account for the wide variety of differences among cultures (and even within our own culture) about which two individuals may and are allowed to marry.  Monogamous relationships can include a man and a woman or two individuals of the same gender (e.g. man and man or woman and woman).  It was the norm until recently in the United States that monogamous marriages were solely between a man and a woman, but with the legalization of homosexual marriage homosexuals may also marry.

Monogamy, however, is not the only type of marriage that exists across the globe.  Plural or polygamous marriages also exist, and these involve the union of more than two individuals.  Another way to look at this concept is to consider it as an individual with multiple spouses.  There are two types of plural or polygamous marriages: polyandry and polygyny. 

Polyandry (poly, meaning many; andr, meaning men) refers to a situation where a female has many male spouses.  Polyandry is present among the various groups or various socioeconomic organizational types (from foragers to state level societies).  A classic example of polyandry exists among the Sherpa of Asia.  The purpose of polyandry among these people was related to inheritance patterns and lack of land resources.  In this culture women inherited property and lands.  There are few land resources available, so women marry multiple men in order to have the men work the land, which is mountainous and requires a great deal of “man power” to cultivate.  In this way, the Sherpa are able to survive in this harsh environment due to their polyandrous marriage patterns.

Polygyny (poly, meaning many; gyn, meaning women) involves a male who has multiple female spouses.  This type of plural marriage is also quite common.  It exists for several reasons, all of which are dependent on the culture where polygyny exists.  For some cultures it is a means of dealing with an overabundance of females within the population.  It can also be a status symbol or symbol of wealth for men who can afford to have multiple spouses.  Ultimately, though, it does appear to have several advantages for females, as they can work together in matters involving their husband, share childcare responsibilities, or negotiate the sexual nature (or lack thereof) of their relationship with their husband.  The Dani of Papua New Guinea practice polygyny, which fulfills a demonstration of wealth and status for the men who are able to support multiple wives.

Ultimately, while family and kinship is a cultural universal there are several variations on this theme.  Not all cultures practice monogamy, instead opting for plural marriages for various reasons (economic or social).  Ultimately, the marriage pattern(s) that exist within a particular society and culture appear to be geographically as well as culturally dependent, hence the variations among cultures.  This just demonstrates that no one way is the best way, and cultural variations allow us to gain better insights into people.    

Bibliography

Gezon, L., & Kottak, C. (2014).  Cultural Anthropology McGraw-Hill  

Scheidel, W.  2008.  "Monogamy and Polygyny in Greece, Rome, and World History."  Princeton/Stanford Working Papers in Classics.

Schwimmer, B.  2003.  "Polygyny."  University of Manitoba.  Website.  

Starkweather, K.E. 2010.  "Exploration Into Human Polyandry: An Evolutionary Examination of Non-Classical Cases."  Masters Thesis.  University of Nebraska.  

Welsch, R.L. & L.A. Vivanco.  (2015).  Cultural Anthropology: Asking Questions About Humanity.  Oxford University Press.

Animal Crackers: Exploring Zooarchaeology

Cache of animal bones (Image Source: www.phys.org)

Archaeology is the study of past peoples and cultures.  It involves the investigation of various material remains, the most notable of which is material cultural evidence (e.g. pottery, weapons, clothing, etc.), but this is an incomplete understanding of all of the aspects of archaeological investigations.  Archaeological studies focus on a variety of features, artifacts, and ecofacts that exist at the site, and today’s blog post will focus on a discussion of what zooarchaeology is, its purpose and importance to the overall study of archaeology, as well as career options for zooarchaeologists.

Zooarchaeology is a branch of archaeological research that focuses on animal remains (i.e. bones, ivory, antler, furs, and skins) that exist in the archaeological record and at archaeological sites.  This subsubdiscipline also goes by other names, including osteoarchaeology, faunal analysis, and archaeozoology.  Archaeologists can gain various insights into past cultures through the study of animal remains, specifically expanding the knowledge base concerning domestication patterns, seasonality of sites (or when sites were occupied), paleoclimate, cultural traditions around ritual and diet, trade patterns, as well as chronology of the site.  This makes zooarchaeology a very useful and dynamic field of study.

Zooarchaeologists, however, have to undergo extensive study within their subsubdisciplines.  Not only do they have to have an understanding of archaeological investigation techniques they also have to know how to identify various species of animals that exist both today as well as existed in the past.  This means that they have to be able to differentiate among mammalian, reptilian, avian, marine/riverine, etc. species.  Not only that but zooarchaeologists also must be able to identify age at death of the animals under study (albeit not to the specificity that bioarchaeologists/physical anthropologists must), as well as the bone element and side.  All of this information allows scholars to understand the details required to answer the research questions derived from the above topics, but zooarchaeologists must complete these analyses most often on fragmentary and worked bone!  Therefore zooarchaeologists must be very patient and disciplined.

Zooarchaeologists are valued members of archaeological teams.  They often acquire employment on academic as well as private archaeological teams as either excavators or lab technicians (and often times both).  They are also employed in museums and conservation organizations.  Ultimately, the possibilities are quite endless within this field, and zooarchaeologists enjoy a wide variety of career options.

Bibliography

  

Keenan, E.  2014.  “Study Animals from the Past with the Techniques of the Future.”  University of York.    https://www.york.ac.uk/archaeology/postgraduate-study/taught-postgrads/masters-courses/zooarchaeology/

  

McClelland, J.  No Date.  “What is Zooarchaeology?”  Stanley J. Olsen Laboratory of Zooarchaeology.  Comparative Vertebrate Collections.  Arizona State Museum.  http://www.statemuseum.arizona.edu/zooarch/

No Author.  No Date.  “Zooarchaeology.”  University of North Texas.  http://geography.unt.edu/sites/geography.unt.edu/files/TXT_Zooarchaeology_0.pdf

 

No Author.  No Date.  “Zooarchaeology.”  University College-London Institute of Archaeology.  University College-London.  http://www.ucl.ac.uk/archaeology/research/tags/zooarchaeology

Schlesinger, JW.  2008.  Zooarchaeology:  The Language of Faunal Remains.  Undergraduate Thesis.