11: The Origin and Dispersal of Modern Humans

sometime around 200kya (definitely by 195kya), the first modern Homo sapiens population appeared in Africa. within another ~150k yrs, their descendents spread all throughout the New World, into Australia, and eventually into the Americas. these are the first hominins that we can confidently refer to as “fully modern human.”

most likely that Homo sapiens evolved from African Homo heidelbergensis.

2 major models for understanding modern human origins: the regional continuity model, and variations on the replacement model.

• regional continuity model: suggests that “local populations in Europe, Asia, and Africa continued their indigenous evolutionary development from premodern Middle Pleistocene forms to anatomically modern humans.” however, big question there is, If our populations evolved separately, how did we all get to be so goddamn similar? in response, this model argues that (1) modern humans are not, actually, all derived exclusively from Africa, and (2) significant levels of gene flow between geographically dispersed premodern populations were extremely likely during the Pleistocene and would account for our similarity. they say we didn’t all evolve independently; we mixed around with each other. this viewpoint also says every hominin that came after Homo erectus counts as Homo sapiens. (most experts think this model is a bit BS.)

• replacement models: emphasize that modern humans evolved first in Africa and then later dispersed to the rest of the Old World, where they replaced the hominins that already lived in those other regions. 2 key sub-versions:

  • complete replacement model: says anatomically modern populations arose in Africa w/in past 200k yrs, migrated out, and fully replaced the other hominin populations already in Europe and Asia. this perspective “doesn’t account for a transition from premodern forms to modern H. sapiens anywhere in the world except Africa.” “a critical deduction of the original [...] theory” argues that anatomically modern humans appeared as the result of a biological speciation event, which would mean they couldn’t interbreed with other hominin species.

    • “As these new data have accumulated, consistent relationships are emerging, especially in showing that indigenous African populations have far greater diversity than do populations from elsewhere in the world. The consistency of the results is highly significant, because it strongly supports an African origin for modern humans and some mode of replacement elsewhere. What’s more, [...] even more complete DNA on contemporary population patterning for large portions of nuclear DNA further confirm these conclusions.”

    • [nuclear] DNA from “Ice Man” as well as 2 7k-yr-old Iberian hunter-gatherers has been sequenced, as well as mtDNA from 9 ancient fully modern Homo sapiens skeletons from sites in Italy, France, the Czech Republic, and Russia.

    • Neandertal genome shows degree of interbreeding with H. sapiens outside of Africa, arguing against complete replacement model and arguing for the partial replacement model

  • partial replacement model: says interbreeding was modest and mostly took place outside of Africa— based on genetic evidence, likely just after Homo sapiens moved out of N Africa and into Middle East, occurring between 80k-50kya.

    • “Were there still other premodern human groups around when modern humans emigrated from Africa— and did they interbreed with modern humans, too? As we discussed in Chapter 10, the answer is yes! Detailed DNA evidence from the fragmentary remains from Denisova Cave in southern Siberia show that these hominins had also interbred with modern humans. What’s more, these Denisovans may have been quite widespread, since a efw of their genes can still be found in Southeast Asian, Pacfic Islanders, and Australian populations today. This recent research has helped to support what appears to have been (at least) a two-stage migration of modern humans into Asia (after an earlier initial migration of modern humans out of Africa). The earlier of these migrations took place through parts of Southeast Asia and eventually reached the South Pacific (including New Guinea and Australia). In fact, the recent whole-genome sequencing using the hair from an Australian Aboriginal man who lived 100 years ago shows that he had Denisovan genes and that Aboriginal populations diverged from other groups 75,000-62,000 ya. The second migration occurred considerably later (38,000-25,000 ya) and led to the peopling of eastern Asia.”

    • thus Fred Smith of Illinois State Uni argues for “assimilation” model hypothesizing that more interbreeding took place in certain regions. not enough evidence thus far, but there is some from analysis of modern humans, which shows more evidence of interbreeding among API populations than European ones.

African specimens

• oldest comes from Omo Kibish in southern Ethiopia. one fragmented skull was radiometrically dated to 195kya. earliest modern human yet found anywhere in the world. one of the interesting feats of the site is that one skull is modern (including a chin), while another that is ostensibly from the same time retains its robustity and does not have the same modern morphology as the other one. key because they’re the oldest modern human remains found anywhere thus far.

• findings from Klasies River Mouth site on southern African coast and from Border Cave just north were dated to ~120-80kya, with Border Cave likely younger than Klasies River Mouth.

• evidence points to modern humans originating in E Africa at ~200kya and migrating to the south by ~100kya.

• 1997 finding in Middle Awash area of Ethiopia by Tim White and colleagues of Herto remains! include a mostly complete adult cranium, an incomplete adult cranium, a fairly complete (but “heavily reconstructed”) child’s cranium, and a few other assorted cranial fragments. radiometrically dated to 160-154kya (when announced in 2003, they were the best-dated hominin fossils from this time period from anywhere in the world; also way older than any other equally modern Homo sapiens from outside of Africa). remains also make it super clear that these were ancestors to modern humans: the mostly-complete adult cranium was very large with an extremely long cranial vault, measuring 1450cm³ (well within range of today’s humans); it was still heavily built in some aspects, including arching supraorbital tori and a “large, projecting occipital protuberance in back;” and face doesn’t project like previous Neandertals. skull is clearly Homo sapiens, as are other remains from the site. concluded that these individuals were on the brink of modernity. to make this distinction, they’re placed in Homo sapiens idaltu, with “idaltu” meaning “elder” in Afar language. key because they’re our one set of fossils that most strongly support African origin theory. genetic data also compatible with some form of replacement theory. also key because they’re the best-preserved early modern human fossils found anywhere in the world thus far.

Skhul Cave site in Palestine yielded modern Homo sapiens fossils of at least 10 individuals. another Palestinian cave, Qafzeh, held remains of 20+ ppl. “overall configuration is definitely modern,” but maintained some ancestral features (little bit of remaining robustity). Skhul findings dated to ~130-100kya; Qafzeh dated to ~120-92kya. modern features on the crania include vault height, forehead, and lack of prognathism. these sorts of findings challenge multiregional model because dating puts both Neandertals and modern Homo sapiens in the same places in the Near East at the same time (indeed, that’s why so many experts point to that region for where we interbred with Neandertals). Skhul remains are earliest modern humans found outside of Africa.

7 “early anatomically modern human localities in China.” key are “Upper Cave at Zhoukoudian, Tianyuan Cave (very near Zhoukoudian), and Ordos, in Mongolia.” these fossils are fully modern. all considered to be from Late Pleistocene and probably <40kya.

• Upper Cave dated to 27kya. findings are 3 skulls with cultural remains in a cave that was clearly inhabited regularly by hominins.

• Ordos skull hypothesized to be very old, but not yet substantiated.

• also: remember from ch10 that some researchers believe the Jinniushan skeleton hints at modern features in China as early as 200kya. this would threaten replacement models, but thus far, there’s not a lotta evidence to support it (especially not recent and detailed analytical evidence) and it’s a minority POV.

• ~4mi from Zhoukoudian Cave is Tianyuan Cave, where, in 2003, researchers found a fragmentary skull, a few teeth, and several postcranial bones. solidly radiocarbon-dated to ~40kya. skull shows mostly modern features with a few ancestral leftovers. the research team has found evidence from the remains supporting theory of African origin, but also shows evidence of interbreeding with premodern populations within China. for now, this is best-dated Chinese Homo sapiens sample, and 1 of 3 of the earliest Homo sapiens from all of Asia.

partial skull from Niah Cave on N Borneo. first excavated ~50yrs ago, but more recent and more extensive analysis, esp of geology of the site, has found strong evidence that it is >35k yrs old, probably between 40-45k yrs (which would make it older than Tianyuan). modern in morphology. hypothesized that some population contemporaneous with Niah or somewhat earlier inhabitants were the ones to originally colonize Australia (ie, the ancestors to those who are today’s Aboriginal population).

2008 find of a human femur dated to ~45kya from Ust’-Ishim in Siberia. complete sequencing of this bone’s nuclear genome indicates mixture of ~2.3% Neandertal, similar to today’s non-African population. also determined individual was male. these findings are key because they give us our earliest genetic info abt modern Homo sapiens and also show evidence that Neandertal interbreeding (a) took place and (b) earlier in history. “However, it’s important to note that the Ust’-Ishim individual does not appear to show a strong affinity to any modern human population, suggesting he may have been part of a lineage that went extinct.”

Australia, mate!

• “During glacial times, the Indonesian islands were joined to the Asian mainland, but Australia wasn’t. It’s likely that by 50,000 ya, modern humans inhabited Sahul— the area including New Guinea and Australia. Bamboo rafts may have ben used to cross the ocean between islands, though this would certainly have been dangerous and difficult. It’s not known just where the ancestral Australians came from, but as noted, Indonesia has been suggested.”

• archaeological evidence of human habitation on Australia dates back to ~55kya. earliest finds so far on Australia come from Lake Mungo in the SE. dated to ~30-25kya.

• finds from Kow Swamp indicate individuals living there from ~14-9kya were different from the more gracile, earlier ones from Lake Mungo—they had certain archaic traits like receding foreheads, heavy supraorbital tori, and thick bones; difficult to explain since these features contrast with the specimens’ postcranial anatomy (which is similar to that of modern Aboriginals).

• more recent genetic evidence suggests all native Australians are descendents of a single migration that happened ~50kya. DNA from modern Aboriginal man indicates divergence of native Australian population occurred sometime even earlier, ~75-62kya.

central Europe!

• lotta finds

• including earliest anatomically modern Homo sapiens yet discovered in Europe found at Osae Cave in Romania in 2002. cranial remains for 3 individuals, including complete mandible and partial skull. still quite robust, but similar to later humans (have chin and canine fossa). DNA from one of the individuals found that ~6-9% of his DNA was Neandertal, and he was only 4-6gens out from Neandertal ancestors (~200yrs). he doesn’t show close affinity with later modern European samples.

• another key site is Mladeč in Czech Republic. found several individuals dated to ~31kya. crania see some variation (esp in supraorbital tori), but pretty confidently placed in Homo sapiens.

• clera that by ~28kya, modern humans were widely dispersed across W and central Europe.

• another find from Dolní Věstonice in Czech Repub found more modern human remains

finds from central Europe generally predate those from W Europe, indicating humans inhabited C Europe first

western Europe

• key find from Cro-Magnon in France. rock shelter. remains of 8 individuals were found there all the way back in 1868. associated with Aurignacian tool assembly (from Upper Paleolithic; industry beginning ~40kya). individuals dated to ~28kya. represent some of France’s oldest anatomically modern humans.

• experts still arguing about interbreeding! “Most of the genetic evidence, as well as the newest fossil evidence from Africa, argues against a continuous local evolution producing modern groups directly from any Eurasian premodern population.” thus researchers agree abt “a large genetic contribution from migrating early modern Africans influencing other groups throughout the Old World,” but they debate about how much interbreeding occurred with the premodern populations who already lived in these regions.

  • evidence for high degree of admixture (assimilation) cite 1998 find of ~24,500k-yr-old child skeleton (at least 5k years younger than last clearly identifiable Neandertal fossil) in Portugal site of Abrigo do Lagar Velho. lotta traits of both Neandertals and modern humans, so the excavators believe this points to partial replacement model of human origins; however, still debatable how much interbreeding would’ve happened (a) at this time and (b) in this area of the world, though, so others say the interbreeding took place earlier and elsewhere and the kid just retained lotta those ancestral/Neandertal traits.

by ~25kya, early modern humans spread throughout Old World (and soon, into New World), but “at about the same time, remnant populations of earlier hominins still survived in a few remote and isolated corners,” like H erectus find from Java that we talked about in ch9, who were super similar to previous H erectus individuals but lasted well into Late Pleistocene (beyond those from other areas). “Even more surprising, it seems that other populations possibly branched off from some of these early inhabitants of Indonesia and either intentionally or accidentally found their way to other, smaller islands to the east. There, under even more extreme isolation pressures, they evolved in an astonishing direction.”

• ie, in 2004, researchers found extremely small-bodied, small-brained hominin remains in Liang Bua Cave on island of Flores east of Java. nicknamed “Flo.” remains of adult female, as well as fragments of ~13 other individuals. Flo is unusual, though she bears resemblance to Dmanisi hominins, because she was barely 3’ tall (as short as tallest australopith), her brain was noly 417cm³ (no bigger than a chimp’s), and she is from ~13kya.

• potentially evolved from earlier Homo erectus populations on Java, but we have no clue how these individuals got to Flores—they could’ve drifted on rafts, but we have no evidence. we just know the lived there for a really long time (recently discovered tools radiometrically dated to at least 1mya). some suggest that these ppl, who are placed in Homo floresiensis, might’ve evolved from ancestors that left Africa even earlier than Homo erectus.

• what we do know is that isolated populations on islands can rapidly evolve to be vv different from rest of populations, with that isolation frequently favouring reduced body size (like the pygmy elephants of the Mediterranean as well as that exact same island). this evolutionary mechanism, known as insular dwarfing, is thought to explain these drastic reductions in body size—they had fewer resources, so they had to evolve to require fewer resources if they were gonna survive.

• looked most like Homo erectus in terms of cranial shape, thickness of cranial bone, and dentition, especially the Homo erectus specimen from Dmanisi. still, they have lotta other derived features unique from other Homos, thus why they get their own species name.

• lotta argument about Flo and co! some ppl argue she was a Homo sapiens with microcephaly; the researchers say “uh excuse me no the fuck not” and point to morphological differences of the cranial and postcranial remains (esp wrist bones) as evidence that she does, in fact, represent a different species. furthermore, it is incredibly unlikely that the one best-preserved cranium of this species would happen to be one with a disorder as rare and severe as microcephaly. that said, it must be acknowledged that “extreme isolation of hominins on Flores leading to a new species showing dramatic dwarfing and even more dramatic brain size reduction is quite unusual.” since we’ve seen it in other mammals, though, and especially other mammals from the same damn island, most experts are inclined to believe that this was indeed a distinct species.

• so! takeaway is that Flo most likely represents a separate species of Homo; she most closely resembles Homo erectus, especially those from nearby Java; and she is anatomically distinct from Homo sapiens, even those with rare conditions like microcephaly.

• haven’t yet been able to successfully sequence Flo’s DNA, but we’re continuing to look into it/try.

period of technology and art in Europe during the Upper Paleolithic begins at ~40kya. cultures usually divided into 5 different industries based on tech surrounding stone tools: Chatelperronian, Aurignacian, Gravettian, Solutrean, and Magdalenian.

period also saw major environmental shifts, with last glacial period at ~30kya seeing warming of temps over thousands of years, partially melting glacial ice; thus lotta Eurasia covered by tundra and steppe (a vast area of treeless country dotted wit lakes and marshes). many northern areas’ permafrost prevented tree growth, but in the short summers, some flowering plants, mosses, and other vegetation could grow, which served as enormous pasture for grazing herbivores, which fed predators, which fed hunters. this ‘pasture’ spread from Spain through Europe and into Russian steppes. lotta reindeer, mammoths, bison, horses, and smaller animals. also saw first human exploitation of fish and fowl. period of relative abundance.

humans spread throughout Eurasia, lived in caves and open-air camps, and built large shelters. also built upon lotta Neandertal tech innovations— far more elaborate burials (eg 24kyo Sungir site in Moscow, where grave goods included “bed of red ochre, thousands of ivory beads, long spears made of straightened mammoth tusks, ivory engravings, and jewelry.” highest human population up to that pt in history occurred during this time in Europe or Africa (we’re unsure which).

climate change often happened quite rapidly, so animals (including us) had to adapt pretty quickly. eg: at 20kya, another climatic “pulse” caused everything to get colder again in Eurasia while continental glaciations reached their maximum extent for this entire glacial period (called the Würm in Eurasia). humans had major advantage of toolmaking, which they were getting better and more sophisticated at quickly. (also prolly other aspects of culture.) it was during this period, in fact, that animals started to really face the threat of humans with weapons (which has continued into the present, ofc).

period of great technological innovation, like the Industrial Revolution of prehistory! invented new and specialized tools, and experimented with and increased the use of new materials like bone, ivory, and antler.

Solutrean tools demonstrate skill (and likely aesthetic appreciation) of Upper Paleolithic: “In this lithic (stone) tradition, skill in modifying rock (called “knapping”) developed to the finest degree ever known. Using specialized flaking techniques, these artisans made beautiful parallel-flaked lance heads, expertly flaked on both surfaces. The lance points are so delicate that they can be considered works of art that quite perhaps never served, nor were they intended to serve, a utilitarian purpose.”

Magdalenian: the final phase of the Upper Paleolithic stone tool industry in Europe. even more advances. development of spear-thrower (atlatl), which was a wooden or bone hooked rod that extended hunter’s arm, enhancing force and distance of spear throw. also made barbed harpoon for catching fish. evidence that bows and arrows first appeared in this period. also developed more efficient ways to make tools, which resulted in “abundance of standardized stone blades,” which could then be fashioned into burins (small, chisel-like tools with a pointed end; thought to have been used to engrave bone, antler, ivory, or wood), borers (to drill holes in skins, bones, and shells), and knives (w/ serrated/notched edges for scraping wooden shafts into a variety of tools).

all this ^ indicates these ppl prolly had more resources available to them, and it might mean more biocultural impacts on humans (more effective tools + use of fire = less need for large teeth and facial skeletons seen in earlier populations).

also first super solid evidence of symbolic representation because of the art they left us! art has been found in lotta Europe as well as Siberia, North Africa, South Africa, and Australia. biggest bit is cave art, but we’ve also found sculptures (like the “Venuses” from Brassempouy, France and Grimaldi, Italy, which were realistically carved female figurines with faces that seem to be those of real women; also statues with exaggerated sex characteristics that were potentially used to promote fertility or for various rituals), and intricately engraved tools/tool handles (widespread throughout Europe and well established by ~33kya (early Aurignacian)).

also technological innovations as a result of art (not just other way around), eg new methods of mixing and applying pigments.

bone and ivory carving and engraving made easier with development special stone tools.

found small animal figures fashioned from fire clay dated to 27-26kya in Czech sites of Dolní Věstonice and Předmostí, which is oldest evidence of ceramic technology from anywhere in world, preceding later pottery invention by >15k yrs.

only in later Upper Paleolithic (esp Magdalenian) that prehistoric art reached climax, with cave art known from >150 sites at this point, mostly in SW France and N Spain. seems ppl from other regions didn’t make art in deep cave walls, perhaps instead on rock faces in the open, resulting in their disappearance over time. most famous cave art are from Lascaux and Grotte Chauvet sites in France and Altamira site in Spain. of these sites, Grotte Chauvet is the oldest at ~35kya.

cave art in Africa, too! Apollo 11 rock-shelter site in Namibia has painted slabs ~28-26k yrs old.

further south, Blombos Cave site found “remarkable bone tools, beads, and decorated ocher fragments” dated to ~73kya.

most recent discovery was Pinnacle Point find in South Africa, where they found ocher (maybe for personal adornment), as well as clear evidence of systematic exploitation of shellfish and use of really small blades. earliest dates of Pinnacle Point are ~165kya, which would be earliest evidence in the world of these behaviours, which many think of as modern human. microliths (dated ~71kya) also show evidence that stone was carefully heated, making it easier to modify into such small tools.

recent find from South African cave Sibudu found what may be “traces of adhesives used to haft stone tools to handles as well as indirect evidence of the possible use of snares and traps to catch small animals,” dated to 70kya. Lyn Wadley says it’s evidence of “complex cognition.”

evidence from Border Cave in South Africa of complex cognition, too, including “use of notched bones, wooden digging sticks, bone awls, bone points, and organic residue likely used for haafting, as well as possible evidence of a wooden poison applicator. These well-preserved organic materials suggest that modern hunter-gatherer adaptations were well developed by 44,000 ya.”

“It is notable that evidence of symbolism is found in Blombos Cave (77,000 ya) and Katanda (80,000 ya), both in Africa, about 45,000 years before any comparable evidence is known from Europe.”

conclusion: for the 2mil yrs before the Upper Pleistocene, hominin development was super slow, but the Upper Pleistocene saw rapid rate of change in culture and technology, theoretically because the brain expanded and reorganized.

“Building on existing cultures, Late Pleistocene populations attained sophisticated cultural and material heights in a seemingly short (by previous standards) burst of exciting activity. In Europe and southern and central Africa, particularly, there seem to have been dramatic cultural innovations, among them big game hunting with new weapons, such as harpoons, spear-throwers, and eventually bows and arrows. Other innovations included needles, “tailored” clothing, hafting of tools, and burials with elaborate grave goods—a practice that may indicate some sort of status hierarchy.”

“The complete replacement model is often referred to as the “Out of Africa” or “Eve” hypothesis.(*) The basic premise of this model is that modern humans were descended from premodern humans (H. heidelbergensis) in Africa as a result of a speciation event.(*) Modern humans—members of a new hominin species—then spread out of Africa (like H. erectus had hundreds of thousands of years earlier) and replaced the premodern humans (e.g., Neandertals) in Europe and Asia.(*) According to this model, there was no interbreeding between modern humans and premodern humans because they were different species. The implication of this is that Neandertals were an evolutionary dead end, and they played no role in our (modern human) evolutionary history.” based originally on studies of mtDNA, but more recent studies have pretty definitively ruled this theory out because, well, we did breed with Neandertals.

• “Although mtDNA changes over time, it is not subject to recombination (via meiosis and sexual reproduction) the way nuclear DNA is. Rather, changes in mtDNA occur only as a result of mutation.”

• that mtDNA study operated on the assumptions that (1) mtDNA with more mutations is older, and (2) mutations of mtDNA have operated on a constant rate over time. however, that may or may not even be true, so lotta researchers challenge the study’s conclusion that since (a) native Africans have the most mtDNA mutations and (b) all of the various mtDNA lineages in the world can be traced back through time to converge in Africa, all living humans have derived from one woman who lived in Africa ~200kya. BUT we don’t know if the “molecular clock” has remained constant throughout time, so we don’t actually know if we’re tracing mtDNA back to one woman 200kya or perhaps to 1 woman way farther back.

• there is, in fact, mounting evidence that Homo sapiens sapiens originated in Africa; what there isn’t much (if any) evidence for anymore is that we never interbred with Neandertals.

“The basic premise of the regional continuity model is that H. erectus populations in various parts of the Old World (Africa, Europe, Asia) simultaneously evolved into premodern and then modern humans. Rather than relying on genetic data, advocates of the regional continuity model focus on fossil evidence. They argue that the fossil record indicates considerable anatomical continuity—from H. erectus, to premodern humans, to modern humans—within each local region, rather than abrupt anatomical changes during the period when the “Out of Africa” hypothesis suggests modern humans spread out and replaced local premodern populations.”

“Key to the regional continuity model is the notion that there has always been some degree of gene flow between different populations, thus preventing speciation after the emergence of H. erectus. (If there were no gene flow, then a scenario in which H. erectus evolved into premodern and then modern humans in multiple regions of the Old World would be highly unlikely, if not impossible.) According to the continuity model, no populations—including Neandertals—ever separated out from the main evolutionary line leading to H. sapiens. Thus, Neandertals would be ancestral to some modern human populations, most likely Europeans.Proponents of multiregional evolution are among the scientists who question the assumption that the rate of mutation in mtDNA has remained constant through time. If it has not, they argue, then there may indeed have been a mitochondrial “Eve,” but much earlier in time—back whenH. erectus became the first hominin to expand its range outside of Africa (i.e., “Eve” would actually have been a female H. erectus, rather than a modern human).”

“Given the most current genetic and fossil data, this third model (which represents a sort of compromise between to two more extreme models I described above) seems most plausible. (*) According to the partial replacement model, modern humans originated in Africa—where they were derived from H. heidelbergensis—but they were not a new species (i.e., there was no speciation event). Instead, these “modern” humans were simply different anatomically from other (“premodern”) H. heidelbergensis populations in Africa.(*) The modern humans then spread out of Africa into Europe and Asia, where—because they were not a new species—they were able to interbreed with local premodern populations, including Neandertals. Thus, according to the partial replacement model, Neandertals could have contributed to the modern human gene pool.”

“A recent study comparing DNA extracted from Neandertal fossils and the genomes of several modern humans (2 African, 1 French, and 2 Asian) indicate that Neandertals and modern humans did in fact interbreed. More specifically, this study indicated that the European and Asian individuals inherited 1-4% of their nuclear DNA from Neandertals, but the Africans did not. Based on these results, the scientists hypothesized that modern humans migrated out of Africa, interbred with Neandertals in the Middle East sometime between 80,000 and 50,000 years ago, and then spread into Europe and Asia.NOTE: The genetic data do not necessarily indicate that lots of interbreeding occurred, as even relatively little interbreeding would be sufficient to explain the patterns evident in the data. In fact, as the scientists who conducted the study pointed out, it is quite interesting that Neandertals and modern humans did not interbreed even more than the data suggest, given that they could (biologically speaking). Perhaps there were significant behavioral/cultural differences between the two groups that discouraged them from interbreeding more frequently (?).”

“A number of researchers have argued that many of the changes that occurred in the skulls of modern humans were related, and that they were a multifaceted adaptation that enhanced our ability to speak. Even the chin—a unique, defining characteristic of modern humans—may have been related, as it could have served to buttress the jaw against stresses involved in speaking and/or chewing. Biological changes in modern humans may also have been reinforced by changes in human cultural behavior. For example, as the tools made by humans became more sophisticated (see below) and humans were able to accomplish more tasks with them—rather than relying solely on brute strength—this would have reduced the selective pressures that favored more robust jaws, teeth, and bodies. This is a good example of the influence of culture on our biological evolution.”

“Current evidence indicates that modern humans had reached China (e.g., Tianyuan Cave) and Southeast Asia (e.g., Niah Cave in Borneo) by 45,000-40,000 ya, and (*) very recently archaeologists found evidence of modern humans in Australia dating to 65,000 ya. (*) Because sea levels were lower at that time, the islands of Borneo, Java, and Sumatra would have been connected to mainland Asia. However, Australia and New Guinea—which constituted a single landmass called Sahul—were not, so modern humans must have crossed at least 50 miles of open ocean in order to reach Sahul.”

“Of the various regions of the Old World inhabited by modern humans, Europe appears to have been the last. The earliest modern human remains found in Europe are about 35,000 years old. The name “Cro-Magnon” is frequently used to refer to these first modern Europeans. This term is derived from the name of a rock shelter in France where early modern human remains were first found in 1868. Both fossil and archaeological evidence indicates that modern humans and Neandertals co-existed in Europe for several thousands of years.”

North American migration!

• “Modern humans were also the first hominins to expand into the Americas. Scientists generally agree that the ancestors of all Native Americans came from eastern Asia. (NOTE: Some Native Americans disagree, and have very different beliefs about their origins.) Evidence indicates that modern humans had expanded into Siberia by 40,000 years ago, and sometime after, they migrated across a land bridge (Beringia) that spanned the Bering Strait and connected Siberia and Alaska during the Pleistocene ice age, when sea levels were lower than they are today. To be sure, the first humans to cross into the Americas were not consciously colonizing a “new world.” Rather, they were simply expanding their range, perhaps following the herds of game animals that they relied upon for food. (*) After crossing the Bering Strait, humans gradually began to migrate south (presumably through ice-free corridors) into North, then Central, and eventually South America.

• “Precisely when the first migration of humans into the Americas happened, and how many waves of migration there were, are hotly debated topics in American archaeology. (*)Interestingly, one of the earliest, well dated archaeological sites in the Americas is Monte Verde, which is located all the way down in Chile! The most secure date from this site is about 12,500 B.C. (that is, 14,500 years before present). Given this, it seems likely that people must have crossed into the Americas long before 12,500 B.C., as it would have taken them a very long time to migrate gradually down into South America. However, for several thousands of years prior to that (as far back as 17,000 ya), much of North America was covered with thick glaciers that would have hindered people’s ability to travel on foot. So this may mean that humans crossed the Bering land bridge even earlier, at least 18,000 years ago. Alternatively, people may have traveled more quickly in some kind of watercraft—not sailing across the open ocean, but rather rafting along the Pacific coast (this possible water route is depicted by a dotted line on the map).

• “Data from Monte Verde and a number of other sites, including Meadowcroft Rockshelter in Pennsylvania, may indicate a much earlier migration (20,000 or even 30,000 years ago!), or that multiple migrations occurred at different times. However, there is considerable debate among archaeologists about these supposed early sites and dates. (*) Unfortunately, many archaeological sites related to the earliest migration(s) into the Americas—assuming they existed—are no longer available to us. Sea levels have risen dramatically since the end of the last Ice Age, which means that many of the coastal areas exposed at that time are now deep under water.

• “Regardless of when the first migration(s) occurred, Clovis points are some of the earliest and most widespread evidence of modern human activity in the Americas. These distinctive projective points, which date to around 11,000 B.C., have been discovered at archaeological sites across North America, and similar points are also found in Central and South America. Clovis points were made during what archaeologists call the Paleoindian period, which began with the arrival of humans in the Americas (whenever that was) and ended around 8000 B.C. (the end of the Pleistocene, or Ice Age). (*) In addition to gathering plant foods and capturing small game, Paleoindians hunted many of the large animals (“megafauna”) that roamed the American landscape during the Pleistocene—including mammoths, mastodons, huge ground sloths, horses, camels, giant beavers and bears, musk oxen, etc. All of these large-bodied animals went extinct around 8000 B.C., and there has been much debate among archaeologists concerning why this happened. One scenario favored by some researchers, known as the “overkill” hypothesis, is that Paleoindians literally hunted the animals into extinction. An alternate hypothesis is that the megafauna went extinct as a result of climatic changes that occurred at the end of the Pleistocene. This second hypothesis now seems more likely, as there is evidence that similar extinctions occurred in other parts of the world around the same time.”

“Evidence gathered over the past couple of decades suggests the intriguing possibility that as modern humans spread across Asia they may have encountered not only the Denisovans (discussed in Unit 9, and earlier in this unit) but also other, very different hominin species. (*) In 2003, researchers working on the island of Flores in Indonesia discovered the partial skeleton of an adult female hominin, as well as assorted bones and teeth from numerous other individuals. Although these individuals—classified as Homo floresiensis—had some clear hominin traits, and they were associated with simple stone tools, the female was only 3 feet tall and had a chimp-sized brain (cranial capacity ~ 400 cc). Not surprisingly, the popular press nicknamed these usual hominins “hobbits.” Initially there was a lot of scholarly debate about whether these individuals were in fact hominins, but most researchers now believe that they represent a separate hominin species that existed until about 60,000 years ago (the oldest skeletal remains are approximately 100,000 years old, and the associated stone tools date between 190,000 and 50,000 ya).

• “NOTE: In 2016 the dates for H. floresiensis were revised based on new stratigraphic data, so the very recent date (13,000 ya) given for H. floresiensis on pg. 302 in your textbook is incorrect (the book was published before the new dates were reported). Also, as you learned last week, even older (700,000 ya) fossils of a small-bodied hominin species—perhaps the ancestor of H. floresiensis—have also been found on Flores more recently, as have 1 million-year-old stone tools.

• “Additional data are needed to determine whether H. floresiensis survived after that time, and thus might have encountered modern humans and/or Denisovans on Flores or elsewhere in southeast Asia. A team of researchers recently reported that they had recovered some 46,000-year-old teeth on Flores, and that they believe the teeth are from H. sapiens. If this is true, it could indicate that H. floresiensis and modern humans co-existed on Flores for a period of time (and by extension, that modern humans played some role in the extinction of H. floresiensis). However, there is still debate about this. There is also considerable uncertainty about the origins of H. floresiensis. Some researchers have posited that H. floresiensis was originally derived from an Asian H. erectus population. However, the results of a recent anatomical study suggest that H. floresiensis was more closely related to H. habilis, and thus may have originated from an earlier hominin ancestor (rather than H. erectus). At this point, we simply do not know exactly when H. floresiensis emerged. We also do not know how the ancestors of H. floresiensis first got to Flores, which would have been an island at that time in the past.”

“Two years ago, researchers reported that the remains of small-bodied hominins dating between 67,000 and 50,000 ya were also found in Callao Cave on the island of Luzon in the Philippines. NOTE: Remember that much older (700,000 ya) stone tools associated with the remains of a butchered rhinoceros have also been found on Luzon, as you learned in Unit 8.Because the remains from Callao Cave—including 7 teeth, 2 finger bones, 3 foot bones, and a fragment of a leg bone—exhibit a set of features that is distinct from other known hominins, researchers gave them a new species name:Homo luzonensis. While H. luzonensis appears to have been small-bodied like H. floresiensis, the remains were too fragmentary to estimate the species’ exact height and attempts to extract DNA from the remains were unsuccessful.”

“At this point you may be wondering, why wereH. floresiensis and H. luzonensis so small? One possible explanation is that their anatomy was shaped by insular dwarfism—an evolutionary process in which small body size is favored in a circumscribed environment (e.g., an island) with very limited resources and a lack of major predators (so large body size would not be necessary). In fact, the remains of dwarf stegodonts (elephant-like animals) have also been discovered on Flores, which supports the hypothesis that insular dwarfism was responsible for the unusual anatomy of H. floresiensis.”

“Anatomically modern humans appeared long before a second kind of modernity—cultural modernity—becomes evident in the archaeological record. (*) Truly modern behavior did not really emerge until the Upper Paleolithic, the third and most recent sub-period of the Paleolithic (Old Stone Age). Beginning around 40,000 ya and lasting until about 10,000 ya, the Upper Paleolithic was marked by major cultural innovations and the emergence of full-blown “modern” human culture. (*) Here, I will focus on three major categories of cultural innovation that occurred during the Upper Paleolithic: tools, settlement, and art.”

“Pressure-flaking—using a tool such as an antler to press small flakes off the edges of a stone tool (rather than simply hitting it with another rock), or to press blades off of a core—allowed humans to shape tools more carefully. People could also re-sharpen a stone tool that had become dull by pressing flakes off its edges.”

“People also made chisel-like stone tools called burins, which in turn were used to fashion a great variety of artifacts out of softer materials, such as bone, antler, horn, and ivory. (*) These included many different kinds of tools (e.g., scrapers, digging tools, spear points, lances, barbed harpoon tips, spatulas, fishhooks, needles with eyes, etc.) as well as beads, bracelets, and other artistic objects.”

“Some spear-throwers made during the Magdalenian period were decorated with carvings of horses, deer, ibex, bison, birds, and fish.”

“Fishhooks made of bone (like the one shown on the right in this image) have been found in Europe; the earliest date to about 14,000 ya. Gorges (toothpick-shaped objects that would lodge in fishes’ mouths) and possibly stone weights used for fishing nets have also been found at sites in Africa.”

“Evidence of food gathering — For example, a wide range of wild plant and animal remains (ecofacts) as well as a grinding stone that may have been used to process wild grains was found at an Upper Paleolithic site called Ohalo in Israel.”

“Bone needles — (*) Dating back to 19,000-18,000 ya in Europe, these remarkable artifacts (like the one shown at left in this image) would have been used to make clothing similar to that worn by historic arctic and subarctic peoples.”

“The sophisticated hearths found in Upper Paleolithic sites clearly indicate that people controlled and used fire, burning wood or bone depending on the availability of these fuel sources. (*) Iron pyrite firestones (which would produce sparks when struck with flint) found in some Upper Paleolithic sites are the earliest evidence we have of humans (or any hominin) actually making fire. (*)Upper Paleolithic humans also fashioned spoon-shaped “lamps” out of sandstone. A person could hold the handle of such a lamp, while animal fat placed in the other, bowl-like end was burned to produce light.”

“Although the earliest European paintings date between about 32,000 and 30,000 ya, most date to the later Upper Paleolithic (21,000-10,000 ya). Also, keep in mind that there are rock art sites in Africa and Australia that are as old—if not older—than those found in Europe, and that humans also produced rock art in places like India and the Americas toward the end of the Pleistocene (Ice Age). In Europe, paintings have been found both on open rock faces as well as deep inside caves. They were made with pigments derived from natural clays and mineral oxides that were painted or blown onto the rock. While most of the paintings clearly represent Ice Age mammals (e.g., bison, horses, mammoths, deer), more abstract geometric shapes also appear at some sites. Humans are rarely represented, although there are examples of hand prints and figures that appear to be half human and half animal.”

proposed interpretations of cave paintings:

• “One of the earliest (and perhaps the most obvious) theories proposed was that the paintings are related to hunting or hunting magic—that is, people painted animals, perhaps as part of a ritual, to ensure that they would have a safe and successful hunt. This hypothesis was based on the fact that many of the paintings depict game animals, sometimes in association with what appear to be spears or darts. Painting (and associated rituals) may also have been intended to influence the fertility of game animals, as some of the animals that appear in the paintings have swollen bellies and udders. While it is possible that at least some of the images were related to hunting, archaeological evidence indicates that the animals depicted in the paintings were not necessarily the same ones that people ate. While the majority of the European images depict horses or bison, the food refuse found in Upper Paleolithic sites indicates that people more commonly ate deer and reindeer.

• “Some researchers have suggested that the paintings may have been intended to communicate information. For instance, they may have played an important role in initiation rites held in the caves, with paintings serving as a medium via which knowledge was passed from adults to youth. More generally, paintings may have been used to transmit information that was essential to people’s survival in Ice Age Europe (e.g., the distribution of game animals and other resources) between different social groups and across generations.

• “Perhaps the most intriguing hypothesis suggested by some scholars is that the various kinds of images depicted in the caves—including not just animals, but also abstract designs and half human-half animal figures—are actually representations of visions that a person would “see” during stages of a trance!

• “Although researchers have generally focused their attention on the beautiful animal representations, some scholars argue that the more abstract signs found in rock art also conveyed meaning.

• “Of course it is also possible that people painted these images simply because they could—that is, they created art simply for art’s sake. Keep in mind that because these paintings are so old and generally are not associated with other archaeological remains, it is very difficult—if not impossible—for us to know for certain why people painted them. In any case, we do know that this is the first time humans expressed their creativity in a visual, “artistic” form.”

“During the Upper Paleolithic, modern humans also began to make portable art, including engraved objects and complete in-the-round sculptures carved out of materials like bone and ivory. (*) Some objects include cumulative markings—such as the tic marks on this artifact from La Marche, France—the meaning of which is still unclear. Some scholars have suggested that such markings represent a form of notation or numerical record-keeping, that they relate to the gestational periods of animals or celestial/lunar cycles, etc. But the truth is, we really don’t know what they mean.”

“The first ceramic (fired clay) objects were also produced in the Upper Paleolithic. At the site of Dolní Věstonice, in the Czech Republic, archaeologists have recovered hundreds of figurine fragments—the earliest ceramic artifacts yet found (dating to about 27,000 ya)—and the remains of a kiln, a covered oven apparently used to fire these artifacts.”

“Venus figurines have been found at many Upper Paleolithic sites across a very wide geographic range, from westernmost Europe all the way to Siberia. Although some of these figurines have elaborately sculpted heads (the example from Brassempouy, France, is especially beautiful), on most Venus figurines only the torso is emphasized, and they commonly have exaggerated female characteristics (breasts, abdomens, hips, thighs, etc.). As is true of Upper Paleolithic art in general, the precise meaning(s) of these figurines remains unclear. Various hypotheses about their meaning have been proposed—e.g., that they were related to fertility (some appear to depict pregnant women); that they depict some form of female deity or Earth goddess; that they reflect the increasing importance of women in society in general (some seem to depict young, non-pregnant, or older females); etc. Even if we cannot determine their exact meaning(s), the relative stylistic uniformity of these figurines across such a vast geographic area suggests that modern humans throughout much of Europe and Asia shared certain symbolic/artistic notions during the Upper Paleolithic.”