Plants/Climate May Be Key to Neanderthal Extinction

When the largest grossing blockbuster, James Cameron’s 3D-Avatar (which earned over $2.24 billion by February 9, 2010) opened in theaters in December 2009, harmony with nature in which the Na’vi (inhabitants of the planet Pandora) received signs from the floating seeds of sacred trees and were “bio-connected” with every living creature produced an innate beauty not much different than the cultures of our indigenous peoples (e.g. Amerindians, Aboriginals, etc.) whose own rich traditions view nature as a sacred, living entity. Perhaps nothing is more telling about our dependence on nature (especially plants) than the Homo neanderthalensis or Neanderthal (a hominid species that existed in areas across Western Europe to Central Asia between 200,000-30,000 years ago with the exception of Iberia (area comprising Gibraltar, Portugal, and Spain) where they persisted until between 24,000-24,500 years ago per Paul Rincon, Did climate kill off the Neanderthals? (BBC News, 13 February 2009)) extinction that occurred approximately 24,000 years ago even though they were highly skilled, intelligent hunters (who also practiced an archaic culture not much different than early Homo sapiens that included utilization of body paint and possible wearing of “jewelry,” as well as creation of art (which was limited since during most of their existence, Neanderthals were struggling to merely survive)). Although genocide, disease, and interbreeding have been mentioned as possible causes, seemingly more benign factors, namely plants and climate, may be the key to their disappearance.

Mt. Toba located on the Indonesian Island of Sumatra unleashed a massive eruption that spewed 800 cubic km of material into the atmosphere in 71,000 BC initiating a millennia-long ice age that per How volcanoes have shaped history (BBC News, 15 April 2010) “could have caused a mass die-off of plant life and a famine for animal species [including] a major ‘bottleneck’ (which means that genetic variation was drastically reduced) in the DNA of human populations [in which] the [Homo sapien] population dropped to between 5,000-10,000 individuals” who at the time were still resident to Africa (which per George Weber, Toba Volcano (28 September 2007) has the largest well-watered tropical landmass in the world”) where plant life persisted in the tropical regions.

Per A Global Winter’s Tale (Discover, 1 December 1998), “Toba buried most of India under [10-20 feet of] ash and… darkened skies over a third of the hemisphere for weeks. Average summer temperatures dropped by 21ºF in high latitudes, [glacial maximum occurred in Europe between 66,000-63,000 BC] and 75% of the Northern Hemisphere’s plants may have died. The effect on humans [was] devastating” due to severe cold and famine.

It is likely during this period that Neanderthals abandoned their ancestral omnivory to engage in a meat-only diet since plant life was scarce to non-existent in their harsh, inhospitable regions while Homo sapiens continued to subsist on both plant and animal products due to the continued albeit lesser availability of plant life within their habitat. Per Danny Vendramini, Them and Us: Neanderthal predation and the bottleneck speciation of modern humans (2007), Neanderthals became carnivorous (consuming up to 2 kg of meat per day) because the “few plants that could survive in the cold climate were not nutritious enough, or required too much effort to collect and process relative to their low nutritional yields.” Consequently, Neanderthals began their move towards extinction since based on research conducted at the Pierre and Marie Curie University, Paris as reported in The Times (5 September 1991) “they had little interest in vegetable foods at all” by 40,000 years ago based on carbon and nitrogen isotopes extracted from Neanderthal bone collagen and additional scientific tests. Homo sapiens, in the meantime, continued to subsist on a slightly more balanced diet that consisted of approximately 50-70% meat and 50-30% plants, respectively.

Based on recent scientific studies and anthropological and archeological evidence, the results were disastrous. The Neanderthal lifespan of barely 40 years was less than 80% of that of Homo sapiens. They developed a genetic intolerance (inability to ingest certain types of foods due to metabolic disorders that prevent their bodies from producing the required enzymes to breakdown and absorb them to create ATP and carbohydrate/fatty reserves) for fruits and vegetables that ultimately led to greater health problems (e.g. poor tolerance for fruit acids, sugar and other carbohydrates, development of skeletal diseases such as arthritis and osteoporosis) including dramatically reduced fertility. Based on a study reported by Jorge E. Chavarro, M.D., Walter C. Willett, M.D., and Patrick J. Skerrett, Fat, Carbs and the Science of Conception (Newsweek, 10 December 2007), “Ovulatory infertility was 39% more likely in women with the highest intake of animal protein than in those with the lowest. The reverse was true for women with the highest intake of plant protein.” Furthermore, they also found that “replacing 25 grams of animal protein with 25 grams of plant protein [resulted in] a 50% lower risk of ovulatory infertility.” Neanderthal men fared little better since their carnivorous diet resulted in elevated levels of ammonia/uric acid production that adversely impacted their sperm count based on a recent study reported by Tamara Sturtz, The infertility timebomb: Are men facing rapid extinction? (Mail Online, 10 May 2010) that warns “men are on a path to becoming completely infertile within a few generations [with] as many as one in five healthy young men between the ages of 18 and 25 producing abnormal sperm counts (only 5-15% of their sperm is good enough to be classed as ‘normal’ under World Health Organization (WHO) [criteria]) [due to environmental and indirect factors such as] women [consuming large amounts] of beef during pregnancy.” Not surprisingly, Neanderthal males lacked “a mutation associated with increased fertility” that enhanced sperm cell flagellum per Ewen Callaway, Neanderthal genome already giving up its secrets (NewScientist, 6 May 2010), for which their plant-free diet over the millennia may have played a contributing evolutionary role.

A key reason small clusters of Neanderthals hung on in Iberia for another 5,000 years after they had vanished elsewhere across Eurasia is because they ingested small amounts of plant material and bontanical fatty acids to supplement their diet based on chemical analyses performed on remains found at the El Salt site in Alicante, Spain per Neanderthal Hearths at El Salt Reveal Plant And Fish Remains (Anthropology.net, 16 September 2009). The resulting enhanced fertility gained from an omnivorous diet likely prolonged Neanderthal survival (that never fully recovered from the Toba-caused bottleneck that was likely more pronounced for them than Homo sapiens due to the fact that per The Neanderthal murder mystery (The Independent, 8 August 2008) “DNA extracted from an adult Neanderthal man who lived near caves in what is now Croatia revealed Neanderthals in Europe probably never numbered more than 10,000 individuals at any one time – a precariously small population size” vulnerable to extinction (since in today’s terms, it likely fell beneath the minimum viable population size (MVP), the effective number to avoid extinction), a confluence of fertility and other health-related problems, higher mortality rate due to their hunting (which included women and children as active participants per Nicholas Wade, Neanderthal Women Joined Men in the Hunt (The New York Times, 5 December 2006)) of some of the biggest and most dangerous species – mammoths, woolly rhinos, large cave bears, bison, wild boar, wolves, and lions (unlike Homo sapiens who were more timid) – and low life expectancy) until another cold spell struck (based on ocean core samples), which likely eliminated most if not all edible plants within their environs since per Professor Chris Stringer of London’s Natural History Museum, as reported by Paul Rincon, it “probably cleared Europe of its forests.” Such a climate change was likely sudden having occurred over a period of several months to a year based on an acute change that occurred roughly 12,800 years ago in which “temperatures had plummeted, with plants and animals rapidly dying over just a few months” in the Northern Hemisphere per Jonathan Leake, Climate change catastrophe took just months (Times Online, 15 November 2009) when a “disruption in the Gulf Stream” blocked the flow of its warm waters to the region due to an influx of fresh water (likely from a glacial discharge) that reduced ocean salinity per Heinrich and Dansgaard-Oeschger events (NOAA, 2006).

Although carnivory presented serious health problems, Neanderthals likely consumed large quantities of and perhaps only meat to tolerate the cold per Danny Vendramini, since a “high protein, high fat, animal meat diet was almost certainly [a] functional constraint imposed by the periglacial European environment.” For many it may have meant the difference between survival and starvation. An examination of 43,000 year-old remains found in the El Sidrón Cave in Spain in 1994 revealed “evidence that during growth [many, perhaps up 75% per another study that entailed examining the dental remains of 669 Neanderthals] had probably gone through a period of starvation” as reported by Rowan Hooper, Did starving Neanderthals eat each other? (NewScientist, 4 December 2006). Consequently, during times of desperation, some engaged in cannibalism “eat[ing] whatever was at hand, even human flesh.” Such cannibalism likely included attacks on Homo sapiens (but the vice-versa is also true based on archaeological evidence) when the opportunity arose and consumption of the remains (e.g. brain, bone marrow) of deceased members of their own species. Such practices, though, were likely uncommon based on archeological evidence that indicate only a tiny minority of Neanderthal remains displayed possible (and in many cases, inconclusive) signs of cannibalism (e.g. bone cuttings resulting from removal of flesh, smashed skulls that could indicate brain removal or non-cannibalistic death caused by a head injury incurred during a fight) and because per What Does It Mean To Be Human: Homo neanderthalensis (Smithsonian National Museum of Natural History, 12 May 2010) “[they] deliberately buried their dead and occasionally even marked their graves with offerings such as flowers” (e.g. Shanidar 4 or “Flower Man,” a deceased male between 30-45 years whose body had been covered with flowers notably yarrow, groundsel, grape hyacinth, and cornflower, to name a few, when he died approximately 60,000 years ago based on pollen samples extracted from around his remains in the Shanidar cave in Iraq).

Therefore, contrary to a few contradictory claims, cannibalistic attacks between Neanderthals and Homo sapiens were likely uncommon since both peoples co-existed peacefully for most of the 50,000-70,000 years they came into contact with each other, which is corroborated by archeological findings that indicate “Cro-Magnon (early Homo sapien) men and Neanderthal men were living side-by-side in Europe for a log period of time [in which] each group had its territory for hunting and never broke the borders” as reported by Pravda on October 24, 2007. Furthermore, routine consumption of human flesh was also unlikely based on a cost-benefit relationship; it is unlikely human flesh could meet Neanderthal dietary needs that amounted to consuming at least 16 burgers per day. Accordingly, it is likely that Neanderthals viewed cannibalism as the vegetation they abstained from – the energy expended was not worth the minimal calories received.

Even though evidence of battles between Neanderthals and Homo sapiens exist based on historical data (e.g. “A [Homo sapien] killed a 40-50 year-old Neanderthal man with a spear in what is now Iraq between 50,000 and 75,000 years ago per Jeanna Bryer, Human Stabbed a Neanderthal, Evidence Suggests (Live Science, 21 July 2009), caves in present-day Israel and the Middle East “changed hands between Neanderthals and [Homo sapiens] no fewer than three times between 47,000 and 65,000 years ago per Harvard University archaeologist Ofer Bar-Yosef as reported in Archaeology: “The Human-Neanderthal Wars” (23 May 2009)), genocide did not initiate the former’s extinction since when the last pocket spent its final days huddled together, sheltering from the cold, arid climate in Gorham’s Cave in Gibraltar, per Paul Rincon, “the two human species never overlapped [and never competed]. [In fact, Homo sapiens were] entirely absent until well after the Neanderthals were gone.”

Interbreeding between Neanderthals and Homo sapiens was rare such that it cannot account for Neanderthal extinction through a merging of the species as some theories postulate. A recent study involving the genome reconstruction of Neanderthal DNA at the Max-Planck Institute for Evolutionary Anthropology in Germany found “that 1% to 4% of the genes carried by [today’s] non-African people are traceable to [Neanderthals]” based on David Brown’s article, Modern Humans, Neanderthals Interbred, Research Shows (The Washington Post, 7 May 2010). According to Svante Pääbo, leader of the study, the interbreeding occurred “someplace in the Middle East about [60,000-]80,000 years ago.” To corroborate DNA evidence that interbreeding was rare even though both hominid species were sexually compatible sharing 99.7% of their DNA based on mtDNA analysis of a 38,000 year-old bone fragment discovered at the Vindija Cave in Croatia in 1980, to date only one hybrid skeleton sharing Neanderthal-Homo sapien traits (the 24,500 year-old remains of a 4 year-old child known as the “Lagar Velho” child discovered in a Portuguese cave in 1998) per Marvin L. Lubenow, Lagar Velho 1 child skeleton: a Neandertal/modern human hybrid (CEN Technical Journal, 2000) has been found. In addition, when discussing the 1%-4% DNA finding, David Reich, a population geneticist at the Broad Institute of MIT and Harvard University stated, “it wouldn’t have taken much mating to make an impact” per Ker Than, Neanderthals, Humans Interbred-First Solid DNA Evidence (National Geographic, 6 May 2010). Though little is known about the interbreeding that took place during rare instances, it is plausible that some resulted through sexual predation when bands of Neanderthals captured and raped Homo sapien females due to the serious fertility problem many of their own women faced, in a futile attempt to stave off extinction.

Analogies equating the terrible toll “Old World” diseases (notably smallpox) took on Amerindians (by 1650 population of Aztecs, Incas, and other Mesoamerican Indians had fallen to only 8 million from the approximately 50 million in 1492 when the first Europeans arrived per La catastrophe démographique (L’Histoire Nº. 322, July-August 2007)) when European explorers came into contact with them due to the former’s absence of immunity, are not applicable with regard to the Neanderthals for several reasons. First, Neanderthals and Homo sapiens co-existed for tens of thousands of years (thus they would have gained immunity to Homo sapien-transmitted diseases), second, the extent of their contact was minimal, and third and most importantly, such claims have not been substantiated by archaeological evidence that indicates that Neanderthals, if anything, were largely infection and disease-free.

In conclusion, based on scientific, historical, archaeological, and anthropological evidence that refute claims that Neanderthal extinction was caused by genocide/war committed by Homo sapiens, competition for the same resources (since Homo sapiens rarely hunted large prey), transmission of Homo sapien diseases for which Neanderthals had no natural immunity, and interbreeding in which both species became one, it is likely that plants and climate are the key. Based on a confluence of inhospitably harsh climactic conditions and the relative absence of vegetation within their habitat, Neanderthals were forced to subsist solely on meat with many experiencing the adverse affects of malnutrition and even starvation. As a result, fertility in Neanderthal men and women declined markedly while their life span remained short such that they never attained MVP and never recovered from the severe bottleneck that had also threatened Homo sapiens with extinction in wake of the Toba super-volcanic eruption and resulting ice ages and severe climate fluctuations.

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