A middle ground?

The Assimilation Model

Proponents of the Assimilation Model incorporate elements from both the Multiregional and the Replacement Model.

http://www.derwinlgray.com/cant-we-all-just-get-along/

Gunter Braumer of the University of Hamburg in Germany suggests that AMH did in fact originate in Africa, but also interbred with Neanderthals to a lesser degree. As I've noted elsewhere, Neanderthals and AMH probably coexisted with Neanderthals in Europe for about 12, 000 years. Rare instances of hybridized skeletons hint at Neanderthal/AMH mating, but would have been a rare event.

I think it's important to remember that Neanderthals were spread over a large geographical area. There may have been several factors at play in their downfall. Perhaps some factors were more consequential than others in specific geographic areas. Perhaps particular events affected some Neanderthal populations more than others. Just because the archeological record is at times conflicting doesn't mean that it's wrong.

Bibliography 

• "Lapedo child." Wikipedia . 21 June 2009. Web. 9 Nov. 2012. <http://en.wikipedia.org/wiki/Lapedo_child>.
• O'Neil, Dennis. "Early Modern Homo sapiens ." EVOLUTION OF MODERN HUMANS: A Survey of the Biological and Cultural Evolution of Archaic and Modern Homo sapiens. Behavioral Sciences Department, Palomar College, San Marcos, California, n.d. Web. 8 Nov. 2012. <http://anthro.palomar.edu/homo2/mod_homo_4.htm>.

Evidence and Implications: Replacement Model

Evidence for the Replacement Model

In this post, I explain the Replacement Model. As a refresher: proponents of this model maintain that AMH actually emerged out of Homo heidelbergensis in Africa about 200, 000 to 150, 000 years ago, and left Africa as recently as 60, 000 to 40, 000 years ago.

http://www.politicalforum.com/current-events/206817-hints-earlier-human-exit-africa.html

 There is archeological and DNA evidence to support the Replacement Model.

The oldest evidence of AMH presence was discovered in Africa. Border cave, near the border between South Africa and Swaziland, yielded fossil remains of AMH dating back to 200, 000 years ago.

View from the mouth of Border Cave

http://en.wikipedia.org/wiki/Border_Cave

Excavations were initiated in 1940 by W. E. Barton. Raymond Dart realized that the bone remains discovered were extremely old. Further excavations were conducted in 1941 and 1942, then in the 1970's by Peter Beaumont. This last expedition yielded a complete infant skeleton as well as the remains of at least 5 hominins.

An aside: they found as many as 69, 000 artifacts, including an artifact later named the "Lebombo bone", a piece of baboon fibula marked by a number of notches thought to represent lunar phases (cool!).

Lebombo Bone, dated to 37, 000 years ago 

http://fyeahblackhistory.tumblr.com/post/26033197671/knowledgeequalsblackpower-the-lebombo-bone-the

Evidence for AMH presence in other parts of the world only begins to appear 60, 000 to 50, 0000 years later in the archeological record. The archeological record thus far does seem to support the Replacement Model, because it clearly indicates that AMH originated in Africa.

Geneticists have used AMH mitochondrial DNA to determine our place of origin. According to them, "the geographic region in which modern people have lived the longest should have the greatest amount of genetic diversity". Turns out, Africa has the world's greatest genetic density. These geneticists therefore conclude that "Mitochondrial Eve" would have lived in Africa 200, 000 to 100, 000 years ago. This evidence also seems to support the Replacement Model.

Eve might have looked something like this

http://www.bradshawfoundation.com/journey/reconstructed-eve.html

Implications of the Replacement Model 

(1) Neanderthal extinction by violence

AMH may have played a major role in Neanderthal downfall as they spread rapidly throughout the world.  Steven Churchill of Duke University is particularly interested in a particular Neanderthal male found at Shanidar Cave in Iraq.

Shanidar 3's fatal rib injury 

Churchill and his team advance that the rib wound was caused by a thrown spear. Only AMH used projectile weapons; Neanderthals are thought to have hunted at close range (sometimes with horrific consequences). It seems that a AMH was directly implicated in the death of this particular individual. 

Alternatively, AMH may have eaten Neanderthals (!). Fernando Rozzi says that a particular Neanderthal jawbone shows evidence of flesh removal, while the teeth might have been used to make a necklace. 

Remnants of a yummy Neanderthal meal?  

http://www.ablogabouthistory.com/2009/05/18/early-humans-may-have-butchered-and-eaten-neanderthals/

(2) AMH outcompeted Neanderthals 

Some archeologists have argued that AMH outcompeted Neanderthals, who after all lived in very similar ecological niches. In an earlier post, I discussed two factors that may have given AMH an edge over Neanderthals: the division of labor and anatomical differences. 

Other hypotheses abound. 

This article says that AMH's longtime partnership with dogs may have "helped humans by transporting meat and other supplies from one place to another, removing an energy burden from their masters which would have given them an advantage when hunting". Proponents, like Pat Shipman, believe that AMH's use of dogs was essential to their success. 

Another article summarizes the recent discovery of the oldest microliths in South Africa. They date back to 71, 000 years ago, and would have been used to make projectile weapons. While these represent our first evidence of microliths, the trend did not actually take root until after 40, 000 years ago. Nonetheless, it's been argued that this early innovation might have eventually allowed AMH to out compete Neanderthals.

Bibliography 

• "Border Cave - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., 1 Aug. 2012. Web. 9 Nov. 2012. <http://en.wikipedia.org/wiki/Border_Cave>.
• Collins , Nick . "Dogs 'helped man out-compete with Neanderthals' - Telegraph." Telegraph.co.uk - Telegraph online, Daily Telegraph, Sunday Telegraph - Telegraph. N.p., 16 Mar. 2012. Web. 9 Nov. 2012. <http://www.telegraph.co.uk/science/evolution/9269523/Dogs-helped-man-out-compete-with-Neanderthals.html>.
• Darling, David . "Lebombo bone." The Worlds of David Darling. N.p., n.d. Web. 9 Nov. 2012. <http://www.daviddarling.info/encyclopedia/L/Lebombo_bone.html>.
• Harrell, Eben. "CSI Stone Age: Did Humans Kill Neanderthals? - TIME." Breaking News, Analysis, Politics, Blogs, News Photos, Video, Tech Reviews - TIME.com. N.p., 24 July 2009. Web. 9 Nov. 2012. <http://www.time.com/time/magazine/article/0,9171,1913769,00.html>.
• McKie, Robin. " How Neanderthals met a grisly fate: devoured by humans | Science | The Observer ."  Latest US news, world news, sport and comment from the Guardian | guardiannews.com | The Guardian . N.p., 16 Mar. 2009. Web. 9 Nov. 2012. <http://www.guardian.co.uk/science/2009/may/17/neanderthals-cannibalism-anthropological-sciences-journal>.
• O'Neil, Dennis. "Early Modern Homo sapiens ." EVOLUTION OF MODERN HUMANS: A Survey of the Biological and Cultural Evolution of Archaic and Modern Homo sapiens. Behavioral Sciences Department, Palomar College, San Marcos, California, n.d. Web. 8 Nov. 2012. <http://anthro.palomar.edu/homo2/mod_homo_4.htm>.
• Wong , Kate. "Arrowheads Hint at How Humans Overtook Neanderthals - Business Insider." Business Insider. N.p., 8 Nov. 2012. Web. 8 Nov. 2012. <http://www.businessinsider.com/arrowheads-hint-at-how-humans-overtook-neanderthals-2012-11>.

Evidence and Implications: the Multiregional Model

Evidence for Multiregional Model 

Proponents of the Multiregional Model see a "strong regional morphological continuity" (Maher 2012) between early and later populations. They argue that modern Europeans share more morphological characteristics with Neanderthals than do non-European populations. Some, like Alan Thorne, suggest that modern Australian populations "share key skeletal and dental traits with pre-modern aborigines who inhabited Indonesia at least 100, 000 years ago".

A family ressemblance? 

http://archives.cantal.fr/?id=286

http://www.artsetsocietes.org/a/a-hurel.html

The archeological record also seems to provide some evidence supporting this model. In 1998, a four year old child with mixed Neanderthal and AMH features dating to around 24, 500 years ago was discovered at Abrigo do Lagar Velho, Portugal. 

Lagar Velho 

http://donsmaps.com/lagar.html

This child has a mostly modern morphology, but also has some Neanderthal traits, like "short lower-limb bones and a backward-sloping mandible". Could this be evidence of gene flow between Neanderthal and human populations? 

Lagar Velho 1: a hybrid love child? 

http://donsmaps.com/lagar.html

In this post, I note that Neanderthals and AMH overlapped in certain geographical areas. I chose to focus on the Levant, where Neanderthals and AMH had similar ecological niches in close spatial proximity. However, the archeological record seems to show a temporal separation between Neanderthals and AMH in this particular region.

The Lagar Velho 1 specimen might be a clue of more direct Neanderthal and AMH contact in other regions.

Excavations of a site in Chatelperron, France, may show evidence for interstratification of Neanderthal and AMH artifacts, prompting some archeologists to suggest that Neanderthals and AMH coexisted in Europe as well.


Implications of Multiregional Model 

Might have Neanderthals and AMH interacted? In the Levant, the presence of each species matches up with climatic events. At first glance, it seems that they would not have interacted at all. But the archeological record is often incomplete and imprecise. On one hand, we may still find convincing evidence of direct interaction; on the other, the dated evidence might be off by a number of years. So Neanderthals and AMH might have actually coexisted in both space and time. Indeed, Paul Mellars thinks that the two species may have therefore had "demographic and cultural interactions".

So what kinds of interactions might they have had?


(1) Interbreeding

http://www.deathandtaxesmag.com/187143/neanderthals-did-not-make-sweet-love-to-humans-say-scientists/


The Lagar Velho 1 specimen has been interpreted as proof of Neanderthal and AMH interbreeding. This source discusses evidence of Modern Europeans interbreeding with Neanderthals around 37, 000 years ago. Scientists from Harvard and the Max Planck Institute (Germany) discovered that Modern Europeans share between 1 and 4% of their genes with Neanderthals.

It's therefore possible that Neanderthals actually "live on"in AMH. Perhaps the two populations mixed together.

http://www.ted.com/talks/svante_paeaebo_dna_clues_to_our_inner_neanderthal.html

However, multiple sources (such as this one) disagree. This source summarizes the research of Andrea Manica of the University of Cambridge. She maintains that the DNA evidence is not a clear indication of interbreeding; instead, it simply shows that "Out of Africa" humans share common ancestry with Neanderthals.

(2) Cultural and Economic exchange?

Remember this post, where I tried to illustrate the shift in our perception of Neanderthals, from ape-like dim-wits to intelligent human-like beings? I cited a good number of authors who suggested that artifacts in the archeological record could serve as proxies for Neanderthal intelligence.

In this paper, Hublin and colleagues prove that the artifacts at the Arcy-sur-Cure were produced by Neanderthals. This was a pretty powerful claim, because the site contained evidence for Chatelperronian industries, which were previously associated only with AMH.

Pendents made by Neanderthals at Arcy-sur-Cure

http://sjohn30.tripod.com/id2.html

At the time, the authors concluded that Neanderthals might have obtained the artifacts by trade or imitation with AMH. The assumption was that Neanderthals could not have produced the artifacts independently of AMH--they simply were not intelligent or creative enough.

This article summarizes findings from the Grotte du Renne in central France. The report says that Neanderthals created body ornaments in imitation of AMH.

http://archaeologynewsnetwork.blogspot.com/2012/10/when-neanderthals-met-homo-sapiens.html#.UJwn0Wk_kUw

Both these articles maintain that AMH influenced Neanderthal culture (not the other way around, by the way). It seems that they may have therefore living in close proximity and might have engaged in some sort of economical or cultural contact.

Of course, as always, some have disputed these claims, saying Neanderthals were perfectly capable of technological innovation.

Bibliography 

• Christensen , Alec . "New Evidence for Multiregional Origins." Latest Articles. John Robinson , 5 Sept. 2001. Web. 9 Nov. 2012. <http://www.freerepublic.com/focus/f-news/517352/posts>.
• d'Errico, Francesco , Joao Zilhao , Michele Julien , Dominique  Baffier , and Jacques  Pelegrin . "Neanderthal Acculturation in Western Europe." Current Anthropology 39 (1998): S1-S44. 
• Gayle, Damien . "Neanderthals 'bred with modern humans in Europe as recently as 37,000 years ago'  | Mail Online." Home | Mail Online. N.p., 5 Oct. 2012. Web. 9 Nov. 2012. <http://www.dailymail.co.uk/sciencetech/article-2213219/Neanderthals-bred-modern-humans-Europe-recently-37-000-years-ago.html>.
• Gugliotta, Guy. "Were Modern Humans Neighbors to Neanderthals?." Washington Post: Breaking News, World, US, DC News & Analysis. N.p., 12 Nov. 2005. Web. 9 Nov. 2012. <http://www.washingtonpost.com/wp-dyn/content/article/2005/09/11/AR2005091100851.html>.
• Hitchcock, Don . "Recent additions, changes and updates to Don's Maps." Don's Maps - Palaeolithic / Paleolithic European, Russian and Australian Archaeology / Archeology . N.p., 15 July 2012. Web. 9 Nov. 2012. <http://donsmaps.com/changes.html>.
• Hublin , Jean-Jacques , Fred Spoor, Marc Braun, Frans Zonneveld, and Silvana Condemi . "A Late Neanderthal Associated with Upper Palaeolithic artefacts ." Nature 381.16 (1996): 224-226. 
• Morton, Glenn. "Neanderthal culture (long)." The American Scientific Affiliation  . N.p., 7 Nov. 1998. Web. 9 Nov. 2012. <www2.asa3.org/archive/asa/199809/0030.html>.
• O'Neil, Dennis. "Early Modern Homo sapiens ." EVOLUTION OF MODERN HUMANS: A Survey of the Biological and Cultural Evolution of Archaic and Modern Homo sapiens. Behavioral Sciences Department, Palomar College, San Marcos, California, n.d. Web. 8 Nov. 2012. <http://anthro.palomar.edu/homo2/mod_homo_4.htm>.
• Pääbo, Svante. "DNA clues to our inner neanderthal". TED global 2011. Jul 2011. Web. 8 Nov. 2012. http://www.ted.com/talks/svante_paeaebo_dna_clues_to_our_inner_neanderthal.html
• Sample, Ian. " Neanderthals live on in DNA of humans | Science | The Guardian ."  Latest US news, world news, sport and comment from the Guardian | guardiannews.com | The Guardian . N.p., 6 May 2010. Web. 9 Nov. 2012. <http://www.guardian.co.uk/science/2010/may/06/neanderthals-dna-humans-genome>.
• Switek, Brian . "Neanderthals smart enough to copy humans." Nature. Nature , 30 Oct. 2012. Web. 8 Nov. 2012. <www.nature.com/news/neanderthals-smart-enough-to-copy-humans-1.11673>.
• Telegraph Reporters. "Neanderthals did not interbreed with humans, scientists find  - Telegraph." Telegraph.co.uk - Telegraph online, Daily Telegraph, Sunday Telegraph - Telegraph. N.p., 14 Aug. 2012. Web. 9 Nov. 2012. <http://www.telegraph.co.uk/science/science-news/9474109/Neanderthals-did-not-interbreed-with-humans-scientists-find.html>.

What do AMH have to do with anything?

In an earlier post, I discussed the evolutionary emergence of Neanderthals. I now need to take a step back, and address two models for the origin and dispersal of AMH. As we will see, each of these models carries important implications for Neanderthal disappearance.

http://anthro.palomar.edu/homo2/mod_homo_4.htm

The Regional Continuity Model

The Regional Continuity Model (also known as the Multiregional Model) is championed by Milford Wolpoff. It states that all modern humans evolved from Homo erectus, who lived in Africa 1.8 mya and eventually colonized most of the world's continents. Modern humans therefore emerged from an "in situ evolution from local populations" (Maher 9/13). Thus, for example, Modern Africans emerged out of African Homo erectus. European Homo erectus would have given rise to Archaic Europeans (for example: Neanderthals), which in term would have evolved into Modern Europeans. Proponents of this theory argue for significant gene flow between each evolutionary branch, but that local subspecies would have coexisted temporally.

The Replacement Model 

The Replacement Model (also know as "Out of Africa Model) proposes that AMH evolved from Homo heidelbergensis in Africa only 200, 000 to 150, 000 years ago. Around 60, 0000 to 40, 000 years ago, AMH left Africa and colonized the rest of the world, replacing other pre-existing archaic humans. Therefore, very little gene flow would have taken place between these populations. This model was originally advanced by Christopher Stringer and Peter Andrews.

In my next post, I will look at supporting evidence for each and possible implications for Neanderthal demise.

Bibliography 

• O'Neil, Dennis. "Early Modern Homo sapiens ." EVOLUTION OF MODERN HUMANS: A Survey of the Biological and Cultural Evolution of Archaic and Modern Homo sapiens. Behavioral Sciences Department, Palomar College, San Marcos, California, n.d. Web. 8 Nov. 2012. <http://anthro.palomar.edu/homo2/mod_homo_4.htm>.
• O'Neil, Dennis. "Glossary of Terms ." EVOLUTION OF MODERN HUMANS: A Survey of the Biological and Cultural Evolution of Archaic and Modern Homo sapiens. N.p., n.d. Web. 8 Nov. 2012. <anthro.palomar.edu/homo2/glossary.htm#gene_flow>.

Division of Labor and Anatomical Differences

What did AMH have that Neanderthals lacked? Could these characteristics help explain why AMH did so well, while Neanderthals died out?

In this post, I will address two less prominent hypotheses on Neanderthal extinction that attempt to answer these questions. 

In this paper, Steven Kuhn and Mary Steiner suggest that a gendered division of labor was a key component of AMH success. According to them, this behavior appeared for the first time in Eurasian cultures of the Upper Paleolithic. 

Neanderthal economies focused primarily on hunting large mammals; periods of relative food abundance would necessarily be accompanied by periods of relative food penuries, leaving little opportunity for Neanderthal populations to grow very much in the long term. 

AMH, on the other hand, broadened their diet to include smaller prey and plants. People no longer needed to engage in cooperative hunting: they were more free to engage in solo and scattered searches for food. Alongside these new behaviors, the authors argue that AMH began to divide labor according to age and sex. 

https://sausociology.wordpress.com/page/3/

In this paper, Karen Streudel-Numbers, Timothy Weaver and Cara Wall-Scheffler show that AMH's longer legs would have enabled them to run more efficiently than Neanderthals, thus allowing the former to conserve energy. The authors suggest that more efficient locomotion might have contributed to AMH success. 

Similar conclusions are reached by J.D. Polk in this paper. He too notes that Neanderthals and AMH had different body masses and limb proportions. His study "demontrat[ed] that primates with relatively long limbs achieve higher walking speeds while using lower stride frequencies and lower angular excursions than shorter-limbed monkeys, and these kinematic differences may allow longer-limbed taxa to locomote more efficiently than shorter-limed species of similar mass". The following clip provides an example of short limb walking--doesn't seems all that efficient... 

Walt Disney. "Uncle Waldo" Aristocats. Youtube, LLC. 20 July 2007. Web 7 Nov. 2012. 

Bibliography 

• Kuhn, S.L., and M.C.  Stiner . "What's a Mother to do? The Division of Labor among Neanderthals and Modern Humans in Eurasia." Current Anthropology 47.6 (2006): 953-981.
• Polk , J.D. . "Influences of limb proportions and body size on locomotor kinematics in terrestrial primates and fossil hominins." Journal of Human Evolution 47.4 (2004): 237-252. 
• Streudel-Numbers, K.L. , T.D.  Weaver, and C.M.  Wall-Scheffler . "The evolution of human running: Effects of changes in lower-limb length on locomotor economy." Journal of Human Evolution 53.2 (2007): 191-196. 

Climate Change

Remember my early post entitled "how close"? In class, Maher suggested that Neanderthal and AMH population turnovers in the Levant were closely linked to abrupt climatic shifts. 

Neandog: "I just can't handle this heat"

http://danshamptons.com/2012/07/18/this-is-how-im-feeling-about-the-weather-lately-in-the-hamptons/

Some archeologists suggest that climate change did have a significant part to play in Neanderthal extinction. 

According to this, Gerd-Christian Weniger and his team from the University of Keulen in Germany combined archeology, paleontology and paleogenetics to show that Neanderthals went extinct due to extreme climate. Weniger suggests that Neanderthals were not able to survive the fourth Heinrich event. The authors argue that while Neanderthals had weathered colder weather before, they were unprepared for the drought that followed. 

This article summarizes Clive Finlayson's The Humans Who Went Extinct. In his book, Finlayson also argues that climatic change was significant. According to him, Neanderthals might have actually have survived until as late as 24, 000 years ago in Spain, Portugal, and Gibraltar. Eventually, though, even this small group of survivors died out after the Heinrich 2 event. 

In this paper, Francisco Jose Jimenez Espejo and his team's analysis of marine sediments shows variation in marine productivity, which is indicative of climatic fluctuation. The authors found that these variations were closely correlated with Homo spatial and occupational patterns. They note that Neanderthals disappeared from Southern Iberia during a particularity harsh and cold climatic period, and therefore suggest that climatic factors may have wiped out Neanderthal populations in this particular geographical area between 24 and 25 thousand years ago. 

Notice that these articles suggest that cold, not heat, did Neanderthals in. Neanderthals may have been morphologically adapted to cold and may have even had clothing... 

http://www.desicolours.com/dont-animals-get-too-cold/10/11/2009

... but may not have been able to find sufficient resources to nourish themselves as hunter-gatherers. 

Some archeologists maintain that climate change did not have any role in causing the Neanderthals to go extinct. Even proponents of climate change can't seem to agree on certain key factors, like when exactly Neanderthals went extinct. If climate change did indeed play a role, perhaps it affected Neanderthals differently depending on particular geographical locations and timing. Neanderthals in the Levant might have been particularly affected by warmer weather in the Levant after 45 kya, while Neanderthals in the Iberian peninsula might not have been able to survive a particularly cold and dry phase around 24 kya.  

Two politicians who can't agree on anything

http://www.foreignpolicy.com/articles/2012/10/24/cant_we_all_just_not_get_along

Bibliography 

• Hadley, Kathryn. "History in the News: News of the Neanderthals." History in the News. N.p., 17 Feb. 2009. Web. 9 Nov. 2012. <http://historytodaymagazine.blogspot.com/2009/02/news-of-neanderthals.html>.
• Jiminez-Espejo , Francisco. "Climate forcing and Neanderthal extinction in Southern Iberia: insights from a multiproxy marine record." Quaternary Science Reviews 26.7-8 (2007): 836-852. Print.
• Jones, Tim. "Neanderthals Dried Fresh Meat, Wore Tailored Clothing – Energy Study « Anthropology.net."  Anthropology.net. N.p., 26 June 2009. Web. 9 Nov. 2012. <http://anthropology.net/2009/06/26/neanderthals-dried-fresh-meat-wore-tailored-clothing-energy-study/>.
• Lemonick, Michael D.. "The Neanderthal extinct due to extreme climate change? « Greenfudge.org." Environmental News With a Sticky Twist - Greenfudge.org. N.p., 5 Dec. 2010. Web. 9 Nov. 2012. <http://www.greenfudge.org/2010/12/05/the-neanderthal-extinct-due-to-extreme-climate-change/>.
• Steegmann, AT Jr, FJ Cerny, and TW Holliday . "Neandertal cold adaptation: physiological and energetic factors.." American Journal of Human Biology 14 (2002): 566-83. Print.
• Wrenn, Eddie. "Guilty! We killed the Neanderthals ... not the ice age like we previously thought (or hoped)  | Mail Online." Home | Mail Online. N.p., 24 July 2012. Web. 9 Nov. 2012. <http://www.dailymail.co.uk/sciencetech/article-2177767/Guilty-We-killed-Neanderthals---ice-age-like-previously-thought-hoped.html>.

What happened to the Neanderthals?

Neanderthals went extinct around 28, 000 years ago. Archeologists are still trying to understand why. In previous posts, I tried to illustrate a shift in our understanding of Neanderthals: from inferior ape-like creatures, they are now usually imagined to be much more human-like in both appearance and behavior.

Well, not always 

http://freethoughtblogs.com/pharyngula/2012/06/19/neandertals-were-monsters/

If AMH and Neanderthals were in fact so similar, why did Neanderthals die out? Why did AMH flourish instead?

Human Demographics: we've been very successful!

http://skepteco.wordpress.com/2011/10/31/7-billion-hearts-and-minds/

Multiple theories have been advanced, with considerable evidence--yet results are often contradictory. In the next series of posts, I will address some of these hypotheses by exploring supporting evidence as well as counter-evidence.