Modern Homo Sapiens Research Articles

Compound haplotypes at Xp11.23 and human population growth in Eurasia.

To investigate patterns of diversity and the evolutionary history of Eurasians, we have sequenced a 2.8 kb region at Xp11.23 in a sample of African and Eurasian chromosomes. This region is in a long intron of CLCN5 and is immediately flanked by a highly variable minisatellite, DXS255, and a human-specific Ta0 LINE. Compared to Africans, Eurasians showed a marked reduction in sequence diversity. The main Euro-Asiatic haplotype seems to be the ancestral haplotype for the whole sample. Coalescent simulations, including recombination and exponential growth, indicate a median length of strong linkage disequilibrium, up to approximately 9 kb for this area. The Ka/Ks ratio between the coding sequence of human CLCN5 and its mouse orthologue is much less than 1. This implies that the region sequenced is unlikely to be under the strong influence of positive selective processes on CLCN5, mutations in which have been associated with disorders such as Dent's disease. In contrast, a scenario based on a population bottleneck and exponential growth seems a more likely explanation for the reduced diversity observed in Eurasians. Coalescent analysis and linked minisatellite diversity (which reaches a gene diversity value greater than 98% in Eurasians) suggest an estimated age of origin of the Euro-Asiatic diversity compatible with a recent out-of-Africa model for colonization of Eurasia by modern Homo sapiens.

Upper Pleistocene Homo sapiens from the Tabon cave (Palawan, The Philippines): description and dating of new discoveries

Among the poor fossil record of Southeast Asian Upper Pleistocene Homo sapiens, the Tabon human remains [12] are frequently cited in the literature despite very scarce published palaeoanthropological data. A recent Filipino-French joint work confirmed the significance of the discoveries made in the 1960s: a frontal bone and two mandibular fragments that have been recently described and dated [9]. Simultaneously, the archaeological potential of the Tabon site has been re-assessed and fieldwork organized by the National Museum of the Philippines yielded another eleven human remains. Palaeoanthropological description and new dating of the human fossils from Tabon cave are proposed and discussed. Some of the new dates obtained confirm the ca. 16 500 BP age of the frontal bone [9], but older ages have been obtained for other human fossils. The palaeoanthropological evidence suggests that all remains pertain to modern Homo sapiens. However, their high morphological variability is discussed in the frame of early Homo sapiens settlements in insular Southeast Asia. To cite this article: F. Detroit et al., C. R. Palevol 3 (2004) .

Auditory hallucinations as primary disorders of syntax: An evolutionary theory of the origins of language

A theory of the evolutionary origins of language is built around: (1) the notion that language is a sapiens-specific capacity that arose in the speciation event that separated modern Homo sapiens from a prior hominid species, and (2) Broca's concept of asymmetry (subsequently recognised as a “torque” from right frontal to left occipital cortices) as the defining characteristic of the human brain. The four chambers of human association cortex thus created allow the separation of “thought” from the speech output and “meaning” from the speech input, these abstractions representing the associations in the nondominant hemisphere of the motor and sensory phonological representations in the dominant hemisphere. The nuclear symptoms of schizophrenia are conceived as manifestations of the breakdown of the boundaries between these four compartments, and as indicating the necessity of the separation of motor and sensory speech engrams as the basis for the speaker-hearer distinction. They further illustrate a requirement for a “deictic core” to the cerebral organisation of language as Mueller and Buehler proposed. In this sense the nuclear symptoms are disorders of the syntax of universal grammar.

The Speciation of Modern Homo Sapiens. Based on a meeting held in London, 28 March 2002. Proceedings of The British Academy, Volume 106.Edited by Tim J Crow. Published for The British Academy by Oxford University Press, Oxford and New York. $50.00. vi + 265 p; ill.; no index. ISBN: 0–19–726246–5. 2002.

Previous articleNext article No AccessHuman Biology & HealthThe Speciation of Modern Homo Sapiens. Based on a meeting held in London, 28 March 2002. Proceedings of The British Academy, Volume 106.Edited by Tim J Crow. Published for The British Academy by Oxford University Press, Oxford and New York. $50.00. vi + 265 p; ill.; no index. ISBN: 0–19–726246–5. 2002.Timothy D Weaver Timothy D WeaverZoology, University of Wisconsin, Madison, Wisconsin Search for more articles by this author Zoology, University of Wisconsin, Madison, WisconsinPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 78, Number 4December 2003 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/382464 Views: 9Total views on this site PDF download Crossref reports no articles citing this article.

Stratigraphic, chronological and behavioural contexts of Pleistocene Homo sapiens from Middle Awash, Ethiopia.

Clarifying the geographic, environmental and behavioural contexts in which the emergence of anatomically modern Homo sapiens occurred has proved difficult, particularly because Africa lacked adequate geochronological, palaeontological and archaeological evidence. The discovery of anatomically modern Homo sapiens fossils at Herto, Ethiopia, changes this. Here we report on stratigraphically associated Late Middle Pleistocene artefacts and fossils from fluvial and lake margin sandstones of the Upper Herto Member of the Bouri Formation, Middle Awash, Afar Rift, Ethiopia. The fossils and artefacts are dated between 160,000 and 154,000 years ago by precise age determinations using the 40Ar/39Ar method. The archaeological assemblages contain elements of both Acheulean and Middle Stone Age technocomplexes. Associated faunal remains indicate repeated, systematic butchery of hippopotamus carcasses. Contemporary adult and juvenile Homo sapiens fossil crania manifest bone modifications indicative of deliberate mortuary practices.

Pleistocene Homo sapiens from Middle Awash, Ethiopia.

The origin of anatomically modern Homo sapiens and the fate of Neanderthals have been fundamental questions in human evolutionary studies for over a century. A key barrier to the resolution of these questions has been the lack of substantial and accurately dated African hominid fossils from between 100,000 and 300,000 years ago. Here we describe fossilized hominid crania from Herto, Middle Awash, Ethiopia, that fill this gap and provide crucial evidence on the location, timing and contextual circumstances of the emergence of Homo sapiens. Radioisotopically dated to between 160,000 and 154,000 years ago, these new fossils predate classic Neanderthals and lack their derived features. The Herto hominids are morphologically and chronologically intermediate between archaic African fossils and later anatomically modern Late Pleistocene humans. They therefore represent the probable immediate ancestors of anatomically modern humans. Their anatomy and antiquity constitute strong evidence of modern-human emergence in Africa.

The Speciation of modern Homo sapiens

The Speciation of modern Homo sapiens

Increased cranial capacity in hominid evolution and preeclampsia

One of the major trends in primate evolution generally and hominid evolution in particular, is cranio-facial contraction accompanied by an increase in cranial capacity. Landmark-based morphometric methods are applied to adult skulls of great apes ( Gorilla, Pan), australopithecines ( Australopithecus and Paranthropus), and humans ( Homo eragster, erectus, neanderthalensis, and sapiens). Morphological changes quantified by vector fields (Procrustes methods) indicate that these skull plans are characterized by distinctive degrees of cranio-facial contraction. These suggest the existence of three discrete skull organization plans: “great ape”, “australopithecine” and “ Homo”. This paper focuses on the “ Homo” skull bauplan and discusses the possible relationships between greatly increased cranial capacity and preeclampsia. The earliest species of the human lineage exhibit less cranio-facial contraction and smaller cranial capacity than Homo neanderthalensis and modern Homo sapiens. Neandertalization introduces a posterior elongation of the skull and leads to a large increase in cranial capacity in the last Neandertals, with values as large as in present-day H. sapiens. Consequently, a new biological hypothesis is proposed to account for the unexplained disappearance of H. neanderthalensis some 30 000 years ago related to the possible appearance of preeclampsia as a factor affecting the survival of the species.

Evidence for a genetic discontinuity between Neandertals and 24,000-year-old anatomically modern Europeans.

During the late Pleistocene, early anatomically modern humans coexisted in Europe with the anatomically archaic Neandertals for some thousand years. Under the recent variants of the multiregional model of human evolution, modern and archaic forms were different but related populations within a single evolving species, and both have contributed to the gene pool of current humans. Conversely, the Out-of-Africa model considers the transition between Neandertals and anatomically modern humans as the result of a demographic replacement, and hence it predicts a genetic discontinuity between them. Following the most stringent current standards for validation of ancient DNA sequences, we typed the mtDNA hypervariable region I of two anatomically modern Homo sapiens sapiens individuals of the Cro-Magnon type dated at about 23 and 25 thousand years ago. Here we show that the mtDNAs of these individuals fall well within the range of variation of today's humans, but differ sharply from the available sequences of the chronologically closer Neandertals. This discontinuity is difficult to reconcile with the hypothesis that both Neandertals and early anatomically modern humans contributed to the current European gene pool.

U-Series dating of Liujiang hominid site in Guangxi, Southern China.

It has been established that modern humans were living in the Levant and Africa ca. 100ka ago. Hitherto, this has contrasted with the situation in China where no unequivocal specimens of this species have been securely dated to more than 30ka. Here we present the results of stratigraphic studies and U-series dating of the Tongtianyan Cave, the discovery site of the Liujiang hominid, which represents one of the few well-preserved fossils of modern Homo sapiens in China. The human fossils are inferred to come from either a refilling breccia or a primarily deposited gravel-bearing sandy clay layer. In the former case, which is better supported, the fossils would date to at least approximately 68ka, but more likely to approximately 111-139ka. Alternatively, they would be older than approximately 153ka. Both scenarios would make the Liujiang hominid one of the earliest modern humans in East Asia, possibly contemporaneous with the earliest known representatives from the Levant and Africa. Parallel studies on other Chinese localities have provided supporting evidence for the redating of Liujiang, which may have important implications for the origin of modern humans.

Human eating behaviour in an evolutionary ecological context.

Present-day human eating behaviour in industrialised society is characterised by the consumption of high-energy-density diets and often unstructured feeding patterns, largely uncoupled from seasonal cycles of food availability. Broadly similar patterns of feeding are found among advantaged groups in economically-emerging and developing nations. Such patterns of feeding are consistent with the evolutionary ecological understanding of feeding behaviour of hominids ancestral to humans, in that human feeding adaptations are likely to have arisen in the context of resource seasonality in which diet choice for energy-dense and palatable foods would have been selected by way of foraging strategies for the maximisation of energy intake. One hallmark trait of human feeding behaviour, complex control of food availability, emerged with Homo erectus (1.9 x 10(6)-200000 years ago), who carried out this process by either increased meat eating or by cooking, or both. Another key trait of human eating behaviour is the symbolic use of food, which emerged with modern Homo sapiens (100000 years ago to the present) between 25000 and 12000 years ago. From this and subsequent social and economic transformations, including the origins of agriculture, humans have come to use food in increasingly elaborate symbolic ways, such that human eating has become increasingly structured socially and culturally in many different ways.

Out of Africa with regional interbreeding? Modern human origins.

A central issue in paleoanthropology is whether modern humans emerged in a single geographic area and subsequently replaced the preexisting people in other areas. Although the study of human mitochondrial DNAs supported this single-origin and complete-replacement model, a recent paper(1) argues that humans expanded out of Africa more than once and regionally interbred. However, both the genetic antiquity and the impact of the African contribution to modern Homo sapiens are so great as to view Africa as a central place of human evolution. Despite the possibility that out-of-Africa H. sapiens interbred with other populations, this evidence is more consistent with the uniregional hypothesis than the multiregional hypothesis of modern human origins.

Interview with a Neanderthal: an Experimental Approach for Reconstructing Scraper Production Rules, and their Implications for Imposed Form in Middle Palaeolithic Tools

This article investigates the degree and nature of ‘imposed form’ in Middle Palaeolithic scrapers, the most common category of stone tool produced by Neanderthals. Novice flintknappers unfamiliar with Middle Palaeolithic tool forms were found to consistently employ two rules in manufacturing scrapers: the striking platform and any adjacent blunt edges were left intact to facilitate prehension, and the longest edge with the most acute spine-plane angle was retouched. Scrapers from three major Middle Palaeolithic sites adhered to these rules in over 90 per cent of cases, but significant divergence from these rules was found in a sample from Skhul cave (Israel) level B1, associated with early anatomically modern Homo sapiens. It is concluded that Middle Palaeolithic scraper manufacture was structured by the need to create a suitable working edge, and to locate that edge to maximize ease and comfort during manufacture and use. The overall shape of the resulting tools was thus not an expression of ‘imposed form’ in the conventional sense. The discovery of violations of these rules in the Skhul B1 collection provides evidence of increased use of imposed form, as well as potentially significant behavioural differences between early anatomically modern Homo sapiens and contemporary Neanderthals.

God-Apes and Fossil Men: Paleoanthropology in South Asia (review)

Reviewed by: God-Apes and Fossil Men. Paleoanthropology in South Asia Lynne A. Schepartz God-Apes and Fossil Men. Paleoanthropology in South Asia. Kenneth A. R. Kennedy. Ann Arbor: University of Michigan Press, 2000. 480 pp.; figures, maps, references, indices. Every paleoanthropologist worth their tenured position knows the intricacies of the archaeological and fossil records for Africa, Europe, Southwest Asia, and China. Yet [End Page 311] how many have more than a passing familiarity with South Asia? With the publication of this work, they can no longer excuse their ignorance. In the preface to this impressive encyclopedic work, Kennedy writes that he is examining the established hypotheses regarding Asian prehistory and population history. Most notably, these are the view that Asia is the cradle of humanity (especially topical now as Chinese researchers reassert claims for the earliest Asian hominid sites); the assignment of different stone tool technologies to specific "races" with ties to living populations; the idea that the origins of the Bronze Age Harappans can be traced to Mesopotamia and the Fertile Crescent; and the notion that a sweeping movement of Indo-European-speaking Aryans coincided with, and probably caused, the decline of Harappan civilization. Underlying all of these ideas is the view that cultural advances and events in South Asia ultimately had their roots elsewhere—and primarily to the west. South Asia was merely the cauldron where diverse peoples and traditions met, clashed, and mingled. Kennedy is one of the leading palaeoanthropologist/ skeletal biologists working in South Asia today, with a research record spanning almost 40 years. With expertise ranging from the early pongids to modern populations, he is eminently qualified to synthesize the palaeoanthropology of the region. The book is strongest where he steps back from the factual coverage and provides his own views on the issues. This is especially true in the latter sections dealing with food-producing populations and the Aryan question. God-Apes and Fossil Men's organization is straightforward and largely chronological. Chapter 1 provides a useful geographical introduction. Chapters 2–4 examine the development of prehistoric, evolutionary, and biological studies in Europe and how those frameworks were imposed on South Asia. While an understanding of these interactions is important, this portion of the book could have been shorter and better integrated. Chapter 5 covers the god-apes of the title: the Rama-, Siva-, Brahma-, and other -pithecines. Kennedy provides a clear discussion of their complex and fluid taxonomy and explains how they weathered the changes in hominid origins research. Only three illustrations are provided, and one of these (Fig. 22) needs an anatomically descriptive caption. More photographs would have enhanced this chapter. The remaining portions of the book detail the human occupation of the region. Geological, archaeological, and faunal information is given first, followed by separate chapters on the human remains, for the earlier time periods. This arrangement has some minor disadvantages because the provenience and burial context are either repeated or given separately from the morphological descriptions. The discussion of the earliest South Asian sites (Chapters 6–8) highlights how little we know from this vast area bridging Africa, Europe, and eastern Asia! While the Potwar Plateau is yielding evidence for some of the earliest stone tool traditions outside Africa, only the Narmada calvaria emerges as a well-documented premodern fossil find. The possibility of the earliest anatomically modern South Asian Homo sapiens coming from sites on Sri Lanka (c. 25–35,000 B.P.) is intriguing but difficult to evaluate without photographs and a more critical examination of the dates and the contexts of the discoveries. The archaeological and human skeletal records expand exponentially for the later time periods, and the richness of South Asian adaptations is apparent. Chapters 9– 11 cover the Holocene hunter-gatherer evidence, and Chapters 12 and 13 describe early farmers and pastoralists. Kennedy rightly highlights the diversity of synchronous developments across the subcontinent, in contrast to earlier accounts that emphasized the role of migration and broad-ranging cultural systems. His thorough examination of the biological and archaeological records reveals little evidence of population replacement, warfare, or aggression. Instead, we are provided a picture of populations who adapted a wide range of technological and economic components...

Evolution's youth movement: Fossil children may harbor clues to humanity's origins

A nthropologists usually don't find the skeletons of long-dead toddlers when digging into ancient ground. But at Syria's Dederiyah Cave, they did just that in 1993 and again in 1997. Excavations at this approximately 60,000-year-old site yielded the partial remains of one small child and the nearly complete skeleton of another. Researchers estimate that both died at around age 2. The Dederiyah youngsters are part of a growing contingent of fossil kids attracting scientific interest. Fossils of children had previously been treated more as oddities than as beacons of evolutionary insight. Now, however, these ancient youths are revealing aspects of human evolution that had evaded scientists studying fossil elders from various Homo species, the first of which appeared around 2.5 million years ago. In particular, infant and juvenile fossils hold clues to a critical issue: the evolution of distinctive patterns of growth in modern Homo sapiens and our immediate ancestors. Understanding individual development may for the first time delineate pivotal differences among Neandertals and several Homo species.

Testing Multiregionality of Modern Human Origins

In order to examine the possibility of multiple founding populations of anatomically modern Homo sapiens, we collected DNA sequence data from 10 X-chromosomal regions, 5 autosomal regions, and 1 Y-chromosomal region, in addition to mitochondrial DNA. Except for five regions which are genealogically uninformative and two other regions for which chimpanzee orthologs are not available, the ancestral sequence and population for each of the remaining regions were successfully inferred. Of these 10 ancestral sequences, 9 occurred in Africa and only 1 occurred in Asia during the Pleistocene. Computer simulation was carried out to quantify the multiregional hypothesis based solely on the premise that there was more than one founding population in the Pleistocene. Allowing the breeding size to vary among the founding populations, the hypothesis may account for the observed African ancestry in 90% of the genomic regions. However, it is required that the founding population in Africa was much larger than that outside Africa. Likelihood estimates of the breeding sizes in the founding populations were more than 9,000 in Africa and less than 1,000 in outside of Africa, although these estimates can be much less biased at the 1% significance level. If the number of African ancestral sequences further increases as more data accumulate in other genomic regions, the conclusion of a single founding population of modern H. sapiens is inevitable.

Major genomic mitochondrial lineages delineate early human expansions

BackgroundThe phylogeographic distribution of human mitochondrial DNA variations allows a genetic approach to the study of modern Homo sapiens dispersals throughout the world from a female perspective. As a new contribution to this study we have phylogenetically analysed complete mitochondrial DNA(mtDNA) sequences from 42 human lineages, representing major clades with known geographic assignation.ResultsWe show the relative relationships among the 42 lineages and present more accurate temporal calibrations than have been previously possible to give new perspectives as how modern humans spread in the Old World.ConclusionsThe first detectable expansion occurred around 59,000–69,000 years ago from Africa, independently colonizing western Asia and India and, following this southern route, swiftly reaching east Asia. Within Africa, this expansion did not replace but mixed with older lineages detectable today only in Africa. Around 39,000–52,000 years ago, the western Asian branch spread radially, bringing Caucasians to North Africa and Europe, also reaching India, and expanding to north and east Asia. More recent migrations have entangled but not completely erased these primitive footprints of modern human expansions.

The place of Neandertals in the evolution of hominid patterns of growth and development

This study uses the two developmental fields of dental maturation and femoral growth to determine if the pattern of growth and development in Neandertals (archaic Homo sapiens) was intermediate between that of Homo erectus and recent modern humans. Specimens used in the analysis included Neandertals and Upper Palaeolithic early modernHomo sapiens from Europe and individuals from two recent modern human populations. Ontogenetic data for the H. erectus adolescent KNM-WT 15000 and for Gorilla gorilla were included for comparison. Previous reports have indicated that H. erectus demonstrates a pattern of ontogeny characterized by earlier and more rapid linear growth than in modern humans. Results reported here demonstrate that Upper Paleolithic early modern Homo sapiens display a growth trajectory indistinguishable from that of recent modern humans. The pattern of Neandertal ontogeny is not intermediate between the pattern displayed in H. erectus and the derived pattern seen in the modern reference samples and the early modern H. sapiens sample. The Neandertal growth trajectory is consistent with either slow linear growth or advanced dental development.

The End of the Neanderthalers: A Speculative Essay

It is suggested that modem Homo sapiens evolved from single small population of Homo erectus, living at high latitude during the last Interglacial period, which lost its body for while retaining the hair, at the same time perhaps reducing the chromosome number from 24 to 23 pairs. This meant that when, at the start of the last Ice Age, they migrated southwards again, viable hybridization with their H. erectus predecessors, still living over most of the rest of the world, might not have been possible. These H. sapiens had pale skins, no longer shielded from the sun by fur, and evolved protective skin pigmentation. In several physiologically different ways, the Neanderthalers are to be regarded as advanced and specialized H. erectus, probably with warm fur coats, rather than as primitive H. sapiens. Key Words: hybridization, extinction, hair, fur, facial flushing, skin coloration. As is generally agreed, the Neanderthalers died out some time before 30,000 years ago, soon after Cro-Magnon Homo sapiens made contact with them during the latter part of the last Ice Age. There is very little fossil or genetic evidence of hybridization between the two populations, and the Neanderthalers seem to have contributed little or nothing to the modern Homo sapiens genotype (Stringer & Gamble 1993. One possible explanation for this puzzling observation could be that when the modern H. sapiens were evolving genetic barrier may have developed which prevented viable hybridization with Homo erectus level populations from which they must have derived. This is how speciation often does occur, when small population becomes isolated, and evolves allopatrically before being brought back in to secondary sympatric contact with the rest of the species. Possibly the 24 pairs of chromosomes characteristic of the chimpanzees and gorillas, and perhaps of all the later hominids, including H. erectus and the Neanderthalers, could have been reduced to the 23 pairs of modern H. sapiens - perhaps by two of the smaller chromosomes joining up as one. Such chromosomal mismatch, although it might not have prevented mating between H. erectus, including the Neanderthalers, and the new H. sapiens, could well have produced inviable hybrids or sterile mules. Something like this was suggested by the well-known Finnish Quaternary biologist Bjorn Kurt6n in his novel, The Dance of the Tiger (Pantheon, New York 1980), concerned with Neanderthalers meeting with the Cro-Magnons at the end of the Ice Age. That was no more than science fiction but it could have happened, and it would explain the otherwise surprisingly rapid disappearance of the Neanderthalers. A Small Isolated Population Such transformation is most likely to have occurred in single numerically-small population. At the same time as the suggested genetical re-arrangement there seems to have been cultural transformation as well, perhaps related to the acquisition of symbolic language, from Palaeolithic stasis over most of the Pleistocene to where we are now, in tens rather than hundreds of thousands of years. This implies that all existing H. sapiens should be descended from one small isolated population, which then spread out over most of the world, replacing the H. erectus already there, including the Neanderthalers. There are some persuasive arguments (Goodhart 1996) to support this suggestion which, although to some extent speculative, is firmly based upon objective evidence. And anyway, Darwin himself observed, in letter to A. R. Wallace dated 22nd December 1857, that he was a firm believer that without speculation there is no good and original observation. Hair and Fur Firstly, although all modern humans have more or less naked bodies, lacking the fur found in all other Primates, humans of many though not all races have plenty of hair on their heads and around the genitalia, and in the armpits, of the long coarse sematic (i. …

High Levels of Sequence Polymorphism and Linkage Disequilibrium at the Telomere of 12q: Implications for Telomere Biology and Human Evolution

The human Xp/Yp telomere-junction region exhibits high levels of sequence polymorphism and linkage disequilibrium. To determine whether this is a general feature of human telomeres, we have undertaken sequence analysis at the 12q telomere and have extended the analysis at Xp/Yp. A total of 22 single-nucleotide polymorphisms (SNPs) and one 30-bp duplication were detected in the 1,870 bp adjacent to the 12q telomere. Twenty polymorphic positions were in almost complete linkage disequilibrium, creating three common diverged haplotypes accounting for 80% of 12q telomeres in the white population. A further 6% of 12q telomeres contained a 1,439-bp deletion in the DNA flanking the telomere. The remaining 13% of 12q telomeres did not amplify with the primers used (nulls). The distribution of telomere (TTAGGG) and variant repeats within 12q telomeres was hypervariable, but alleles with similar distribution patterns were associated with the same haplotype in the telomere-adjacent DNA. These data suggest that 12q telomeres, like Xp/Yp telomeres, exhibit low levels of homologous recombination and evolve along haploid lineages. In contrast, high levels of homologous recombination occur in the adjacent proterminal regions of human chromosomes. This suggests that there is a localized telomere-mediated suppression of recombination. In addition, the genetic characteristics of these regions may provide a source of deep lineages for the study of early human evolution, unaffected by both natural selection and recombination. To explain the presence of a few diverged haplotypes adjacent to the Xp/Yp and 12q telomeres, we propose a model that involves the hybridization of two archaic hominoid lineages ultimately giving rise to modern Homo sapiens.