Guest Post: Hominid Profiles

The following is a guest post by a former students, Destiny Fite & Tammy Winters, whose exemplary work on hominids warranted publication.  This post is being published now as both students opted to focus on their studies and school work and returned their edited paper after the end of term.  A prudent decision on their parts.  I hope this informative review on hominids provides you, the readers, with plenty of food for thought.

Neanderthal

Homo neandertalensis

By: Destiny Fite 

The Homo neandertalensis, or Neandertals, are generally considered the closest archaic relative and subspecies to Homo sapiens sharing physical, intellectual, and cultural similarities. Although the Homo neandertalensis is an entirely different species than Homo sapiens, both species evolved from the same common ancestor. The now extinct Neandertals inhabited geographic areas of Europe and Asia until the species disappeared nearly 28,000 years ago without any concrete explanations. While little is known about their disappearance, the fossil and cultural evidence collected from the Homo neandertalensis species provides insight into Homo sapiens closest known relative. 

According to the National Museum of Natural History, the Neandertals inhabited geographic areas of Europe and southwestern to central Asia approximately 200,000 to 28,000 years ago evolving from the same common ancestor as Homo sapiens. According to the text Introduction to Human evolution and Prehistory, the first Neandertal fossil was discovered in Neander Valley, Germany in 1856, thus giving the species the scientific name Homo neandertalensis. Present day, “nearly 400 Neandertal individuals…have been collected” with fossils distributed across “western Asia, including Israel, Iraq, Russia and Uzbekistan” (339). 

The analysis of the skeletal remains collected in the last 200 years provides a detailed profile of the anatomy and physical appearances of the common Neandertal male and female. The Homo neandertalensis species may have evolved from the Homo heidelbergensis because they share more similar physical characteristics than other species. The anatomy of the Homo neandertalensis reveals that this species was well adapted to colder climates having robust bodies with signs of heavier musculature attachments. The average male stood about five feet tall with an average weight of 143 lbs. Males were generally taller and heavier than the female but the comparison of Neandertal skeletal remains yields very little sexual dimorphism (Homo neanderthalensis). According to the text Introduction of Human Evolution and Prehistory, the skull also has distinctive features different from other hominid species characterized by a large and wide nasal opening, large orbits and pronounced brow ridges, low and flat cranium, occipital bun, and a projecting jaw. The Neandertal posture was once believed to be hunched over similar to the posture of an ape due to an incorrect analysis of a nearly complete skeleton excavated in La-Chapelle-aux-Saints, France in 1908. A reanalysis of the skeleton revealed the 40 year old man actually had severe arthritis in his spine. Although the classic cave-man hunched posture is still portrayed, the Homo neandertalensis species was completely bipedal just like the modern human (Dr. O’Neil, Dennis). In fact, the Neandertals were similar to Homo sapiens in physical appearance, intelligence, and even culture. 

Neandertal cultural evidence shows that the species made and used a variety of tools known as the Mousterian tradition “characterized by an increase in the number and variety of flake tools and an ultimate deemphisis of the hand axe” (Rowe, Bruce M). Excavations have surfaced nearly 20 different types of tools serving many different purposes. The Neandertals were skilled hunters of larger animals and various tools appear to assist in hunting and slicing meat. Other tools appear to be useful toward scraping hides and cutting wood as a means of building both fire and shelter.

Archeologists have also found numerous Neandertal skeletons that appear to be buried deliberately. Evidence reveals that the species placed specimens and artifacts such as flowers upon the graves suggesting ritualistic burials (Origins of Humankind). The Neandertals were more similar to modern humans in appearance and culture than previously assumed. Comparisons of skeletal remains reveal significant physical differences; however, according to the article, “Neanderthal-human Hybrids” written by Paul H. Mason and Roger V. Short, genetic evidence of Neandertal nuclear DNA in modern living humans suggests that the two species may have interbred as the Homo sapiens migrated out of Africa into Europe. This theory is highly debatable because there is not enough concrete evidence to prove interbreeding; however, genetic studies have extracted Neandertal nuclear DNA from nearly every modern ethnic race aside from the African race (Than, Ker). Genetic evidence does imply “only Neanderthal males were only able to mate with female humans” and “produce fertile offspring” due to the lack of Neandertal mitochondrial DNA (Mason, Paul H and Short, Roger V). It is also a possibility that any viable offspring produced by female Neandertals and male humans became extinct along with the rest of the species.

There are several theories regarding the mysterious disappearance of the Homo neandertalensis species. According to the Dr. Dennis O’Neil in the Behavioral Sciences Department at Palomar College in San Marcos, California, some theorists believe that the rapid growth and migration of more evolved and technologically advanced species such as the Homo sapiens caused the Neandertals to become extinct. Others assume that their extinction is connected to the “coldest phase of the last ice age” because the species did not “develop adequate technology for severe cold winter conditions” (Dr. O’Neil). However, there is not enough concrete evidence in either theory to prove cause of extinction. The lack of information regarding their disappearance does not displace the fossil and cultural evidence collected from the Homo neandertalensis species providing insight on the Homo sapiens closest known relative.

 Works Cited

Homo neanderthalensis. Smithsonian Institution. National Museum of Natural History. Web. 18 Apr 2014. <www.humanorigins.si.edu>

Rowe, Bruce M. Chapter 14. Introduction to Human Evolution and Prehistory. By Philip L. Stein. McGraw-Hill Education, 2014. Pg 344. Print.

Origins of Humankind. WGBH Educational Foundation. 2001. Web. 18 Apr 2014. <www.pbs.org>

O’Neil, Dr. Dennis. Analysis of Early Hominins. Retrieved from Behavioral Sciences Department of Palomar College, San Marcos, California. Web. 06 Apr 2014.

< http://anthro.palomar.edu/hominid>

Mason, Paul H., Short, Roger V. Neanderthal-human Hybrids. Hypothesis, 2011. Vol. 9.1 Web. 14 Apr 2014. <hypothesisjournal.com>

Than, Ker. Neanderthals, Humans Interbred—First Solid DNA Evidence. National Geographic Society News. National Geographic Society. 06 May 2010. Web. 14 Apr 2014. <.news.nationalgeographic.com>

 

Australopithecus sebida

 Australopithecus sediba

By: Tammy Winters

Australopithecus sediba is an ancient hominid species. This essay will compare the morphological features that define this species as an Australopithecine. I will compare these morphological qualities to those of the Homo species and indicate whether it should or should not be categorized as a member of the Homo species. As there is still much debate on the taxonomic naming of this species I will provide evidence supporting both sides of this argument. Lastly, I will conclude my opinion if Australopithecus sediba is indeed an ancient relative to the modern human species or if it should remain as a Australopithecine. Could this species be the “missing link?”

The recent find of paleoanthropologist Lee Berger of the University of the Witwatersrand in 2008 presented hominid fossils dating to 1.98 million years ago. The hominid fossil remains of Australopithecus sidiba were found in a limestone cave of Malapa, South Africa. The fossils show a mixture of morphological evidence of Australopithecus and the Homo species
A change in brain capacity from 400 cubic centimeters approximately 850 cubic centimeters is what suggests the morphological change from the Australopithecine species to Homo species. Australopithecus sediba has a brain capacity of 420 cubic centimeters categorizing it as an Australopithecine, but the shape and expanded regions of the frontal lobe suggest Homo qualities. Dr. Kristian Carlson conducted a study on the shape and formation of the fossil remains of a juvenile male. Results from the endocasts of the juvenile Australopithecus sediba indicated orbital frontal shape and organization that align more closely with modern human endocasts. The finding suggests that brain reorganization came before the change in brain size. This find may indicate a higher level of understanding and could possibly categorize the species as Homo if there were proven methods of tool use. This is still speculated as no tools have been found at the site.

The well preserved upper limbs of Australopithecus sediba suggest climbing and suspensory ability evidenced by predominantly primitive features. such as the shortened clavicle and bowed ulnar These features are more closely related to the chimpanzee, suggesting an arboreal adaptation. A nearly complete hand and wrist were found and indicate Australopithecus sediba had the use of precision grip and the ability to manipulate tools. This discovery gives the fossils Homo qualities , but the shortened clavicle indicates more primate like morphology. It is suggested that the climbing ability may have been due to the habitat of a rocky terrain and the need to climb this terrain the obtain shelter in caves. The legs and feet show that Australopithecus sediba used bipedal locomotion with a previously unknown method of upright walking. They also show combined traits of arboreality which may indicate the transition from arboreal to bipedal locomotion. Fragments of the vertebral column were found and all four sections of the spine are represented. Australopithecus sediba has the same number of vertebra as modern humans, including a flexible lower spine. Australopithecus sediba likely possessed five non-rib-bearing lumbar and five sacral elements resulting in a functionally longer lower back and indicating lordotic posture similar to the spine of Homo erectus. A broader lower chest and wider pelvic girdle are also found in the species. It is suggested these features may have evolved before other features in Homo.

Due to the mosaic of features present in Australopithecus sediba it is still being debated on whether it should be categorized as the species Homo or Australopithecus. The scientist who discovered Australopithecus sediba believes it should be categorized in the genus Homo because the broader pelvis, lower limbs, and dentition are more human like. Co-author of the project, Steven Churchill and his colleagues believe Australopithecus africanus gave rise to Australopithecus sediba which is suspected to evolve into Homo erectus. They also believe some of the Australopithecine species such as Homo rudolfensis more likely fall in the genus of Australopithecus.

Critics of this find believe Australopithecus sediba presents more ape-like morphology due to the appearance of the feet and ankle bones as well as the long arm length. They also believe Australopithecus sediba may be a subspecies of Australopithecus afticanus. Professor Lee Berger disputes this accusation because of post cranial and dentition differences between the two species.

In conclusion the mosaic skeletal remains of Australopithecus sediba makes classifying this species difficult. The debate on whether or not Australopithecus sediba is indeed an Australopithecine and not an ancestor of Homo still continues. Certainly the brain capacity of Australopithecus sediba give this species Australopithecine qualities, however the frontal lobe changes make it more Homo like. The transition for arboreal locomotion to bipedal locomotion is evident in this species, as well. The increase size of the ilium in the pelvic girdle and precision grip of the hands also align Australopithecus sediba with the Homo genus. While still not convinced Australopithecus sediba is the “missing link,” I do side with the founder of the species that it indeed has relevant Homo qualities and could potentially be deemed even another species falling between Australopithecine and Homo.



Works Cited

Barras, Colin. "Human 'missing Link' Fossils May Be Jumble of Species." Human 'missing Link' Fossils May Be Jumble of Species. New Scientist, 09 Apr. 2014. Web. 16 Apr. 2014.

Berger, Lee R. "Go to Science." Science Magazine: Sign In. Science Mag.org, 09 Apr. 2010. Web. 16 Apr. 2014.

Carlson, Kristain J. "The Endocast of MH1, Australopithecus Sediba." The Endocast of MH1, Australopithecus Sediba. Science Mag.org, 8 Sept. 2011. Web. 16 Apr. 2014.

Churchill, Steven E. "The Upper Limb of Australopithecus Sediba." The Upper Limb of Australopithecus Sediba. Science Mag.org, 12 Apr. 2013. Web. 16 Apr. 2014.

Switek, Brian. "New Studies Shake Up Human Family Tree." News.nationalgeographic.com. National Geographic News, 04 Apr. 2013. Web. 15 Apr. 2014.

Wayman, Erin. "Fossil Finds Complicate Search for Human Ancestor." Smithsonian. SMITHSONIANMAG.COM, 09 Sept. 2011. Web. 16 Apr. 2014.

Williams, Scott A. "The Vertebral Column of Australopithecus Sediba." The Vertebral Column of Australopithecus Sediba. Science Mag.org, 12 Apr. 2013. Web. 16 Apr. 2014.