Only in Africa

2021 ◽  
Author(s):  
Norman Owen-Smith
Keyword(s):  
Plate Tectonics ◽  
Common Ancestor ◽  
Great Apes ◽  
Modern Humans ◽  
Evolutionary Transitions ◽  
Distinctive Features ◽  
Out Of Africa ◽  
Physical Features

That humans originated from Africa is well-known. However, this is widely regarded as a chance outcome, dependant simply on where our common ancestor shared the land with where the great apes lived. This volume builds on from the 'Out of Africa' theory, and takes the view that it is only in Africa that the evolutionary transitions from a forest-inhabiting frugivore to savanna-dwelling meat-eater could have occurred. This book argues that the ecological circumstances that shaped these transitions are exclusive to Africa. It describes distinctive features of the ecology of Africa, with emphasis on savanna grasslands, and relates them to the evolutionary transitions linking early ape-men to modern humans. It shows how physical features of the continent, especially those derived from plate tectonics, set the foundations. This volume adequately conveys that we are here because of the distinctive features of the ecology of Africa.

scholarly journals The quantity of Neanderthal DNA in modern humans: a reanalysis relaxing the assumption of constant mutation rate

2016 ◽  
Author(s):  
William Amos
Keyword(s):  
Mutation Rate ◽  
Common Ancestor ◽  
Alternative Hypothesis ◽  
Large Contribution ◽  
Modern Humans ◽  
Out Of Africa ◽  
Loss Of Diversity ◽  
Induced Changes

AbstractFew now dispute that a few percent of the DNA of non-African humans is a legacy of interbreeding with Neanderthals. However, heterozygosity and mutation rate appear to be linked such that the loss of diversity associated with humans migrating out of Africa caused a mutational slowdown, allowing Africans to diverge more from both our common ancestor and Neanderthals. Here I use a range of contrasting tests aimed at distinguishing between mutation slowdown and introgression as explanations for the higher rates of base-sharing between non-Africans and Neanderthals. In every instance the mutation slowdown hypothesis fits better. Thus, while some interbreeding likely occurred, as evidenced by the finding of skeletons of admixed individuals, adaptive genes and the apparently large contribution of Denisovan DNA to Oceanian genomes, my results challenge the idea that non-Africans generally carry an appreciable Neanderthal legacy. My analysis shows that inferences about introgression may be unreliable unless variation in mutation rate linked to demographically induced changes in heterozygosity can be excluded as an alternative hypothesis.

scholarly journals Correlated and geographically predictable Neanderthal and Denisovan legacies are difficult to reconcile with a simple model based on inter-breeding

2021 ◽  
Vol 8 (6) ◽  
pp. 201229
Author(s):  
William Amos
Keyword(s):  
North Africa ◽  
Common Ancestor ◽  
Test Group ◽  
Great Apes ◽  
Strongly Correlated ◽  
Genome Diversity ◽  
Large Dataset ◽  
Neutral Drift ◽  
Out Of Africa ◽  
Project Data

Although the presence of archaic hominin legacies in humans is taken for granted, little attention has been given as to how the data fit with how humans colonized the world. Here, I show that Neanderthal and Denisovan legacies are strongly correlated and that inferred legacy size, like heterozygosity, exhibits a strong correlation with distance from Africa. Simulations confirm that, once created, legacy size is extremely stable: it may reduce through admixture with lower legacy populations but cannot increase significantly through neutral drift. Consequently, populations carrying the highest legacies are likely to be those whose ancestors inter-bred most with archaics. However, the populations with the highest legacies are globally scattered and are unified, not by having origins within the known Neanderthal range, but instead by living in locations that lie furthest from Africa. Furthermore, the Simons Genome Diversity Project data reveal two distinct correlations between Neanderthal and Denisovan legacies, one that starts in North Africa and increases west to east across Eurasia and into some parts of Oceania, and a second, much steeper trend that starts in Africa, peaking with the San and Ju/’hoansi and which, if extrapolated, predicts the large inferred legacies of both archaics found in Oceania/Australia. Similar ‘double’ trends are observed for the introgression statistic f 4 in a second large dataset published by Qin and Stoneking (Qin & Stoneking 2015 Mol. Biol. Evol. 32 , 2665–2674 ( doi:10.1093/molbev/msv141 )). These trends appear at odds with simple models of how introgression occurred though more complicated patterns of introgression could potentially generate better fits. Moreover, substituting archaic genomes with those of great apes yields similar but biologically impossible signals of introgression, suggesting that the signals these metrics capture arise within humans and are largely independent of the test group. Interestingly, the data do appear to fit a speculative model in which the loss of diversity that occurred when humans moved further from Africa created a gradient in heterozygosity that in turn progressively reduced mutation rate such that populations furthest from Africa have diverged less from our common ancestor and hence from the archaics. In this light, the two distinct trends could be interpreted in terms of two ‘out of Africa’ events, an early one ending in Oceania and Australia and a later one that colonized Eurasia and the Americas.

scholarly journals Experimental evidence for yawn contagion in orangutans (Pongo pygmaeus)

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Evy van Berlo ◽  
Alejandra P. Díaz-Loyo ◽  
Oscar E. Juárez-Mora ◽  
Mariska E. Kret ◽  
Jorg J. M. Massen
Keyword(s):  
Experimental Evidence ◽  
Common Ancestor ◽  
Great Apes ◽  
Pongo Pygmaeus ◽  
Last Common Ancestor ◽  
Contagious Yawning ◽  
Proximate Mechanism ◽  
Social Species ◽  
Ultimate Causation

AbstractYawning is highly contagious, yet both its proximate mechanism(s) and its ultimate causation remain poorly understood. Scholars have suggested a link between contagious yawning (CY) and sociality due to its appearance in mostly social species. Nevertheless, as findings are inconsistent, CY’s function and evolution remains heavily debated. One way to understand the evolution of CY is by studying it in hominids. Although CY has been found in chimpanzees and bonobos, but is absent in gorillas, data on orangutans are missing despite them being the least social hominid. Orangutans are thus interesting for understanding CY’s phylogeny. Here, we experimentally tested whether orangutans yawn contagiously in response to videos of conspecifics yawning. Furthermore, we investigated whether CY was affected by familiarity with the yawning individual (i.e. a familiar or unfamiliar conspecific and a 3D orangutan avatar). In 700 trials across 8 individuals, we found that orangutans are more likely to yawn in response to yawn videos compared to control videos of conspecifics, but not to yawn videos of the avatar. Interestingly, CY occurred regardless of whether a conspecific was familiar or unfamiliar. We conclude that CY was likely already present in the last common ancestor of humans and great apes, though more converging evidence is needed.

scholarly journals Revisiting the Out of Africa event with a novel Deep Learning approach

2020 ◽  
Author(s):  
Francesco Montinaro ◽  
Vasili Pankratov ◽  
Burak Yelmen ◽  
Luca Pagani ◽  
Mayukh Mondal
Keyword(s):  
Deep Learning ◽  
Sequential Monte Carlo ◽  
Whole Genome Sequence ◽  
Learning Approach ◽  
Whole Genome ◽  
Modern Humans ◽  
Anatomically Modern Humans ◽  
Out Of Africa ◽  
Approximate Bayesian ◽  
Back To Africa

AbstractAnatomically modern humans evolved around 300 thousand years ago in Africa1. Modern humans started to appear in the fossil record outside of Africa about 100 thousand years ago though other hominins existed throughout Eurasia much earlier2–4. Recently, several researchers argued in favour of a single out of Africa event for modern humans based on whole-genome sequences analyses5–7. However, the single out of Africa model is in contrast with some of the findings from fossil records, which supports two out of Africa8,9, and uniparental data, which proposes back to Africa movement10,11. Here, we used a novel deep learning approach coupled with Approximate Bayesian Computation and Sequential Monte Carlo to revisit these hypotheses from the whole genome sequence perspective. Our results support the back to Africa model over other alternatives. We estimated that there are two successive splits between Africa and out of African populations happening around 60-80 thousand years ago and separated by 12-13 thousand years. One of the populations resulting from the more recent split has to a large extent replaced the older West African population while the other one has founded the out of Africa populations.

scholarly journals Arguments that Prehistorical and Modern Humans Belong to the Same Species

2019 ◽  
Author(s):  
Rainer Kühne
Keyword(s):  
Homo Sapiens ◽  
Single Species ◽  
Homo Erectus ◽  
Modern Humans ◽  
Homo Neanderthalensis ◽  
Out Of Africa

I argue that the evidence of the Out-of-Africa hypothesis and the evidence of multiregional evolution of prehistorical humans can be understood if there has been interbreeding between Homo erectus, Homo neanderthalensis, and Homo sapiens at least during the preceding 700,000 years. These interbreedings require descendants who are capable of reproduction and therefore parents who belong to the same species. I suggest that a number of prehistorical humans who are at present regarded as belonging to different species belong in fact to one single species.  

Evidence for a humid interval at ∼56–44 ka in the Levant and its potential link to modern humans dispersal out of Africa

2018 ◽  
Vol 124 ◽  
pp. 75-90 ◽  
Author(s):  
Dafna Langgut ◽  
Ahuva Almogi-Labin ◽  
Miryam Bar-Matthews ◽  
Nadine Pickarski ◽  
Mina Weinstein-Evron
Keyword(s):  
Modern Humans ◽  
Potential Link ◽  
Out Of Africa

scholarly journals Femoral ontogeny in humans and great apes and its implications for their last common ancestor

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Naoki Morimoto ◽  
Masato Nakatsukasa ◽  
Marcia S. Ponce de León ◽  
Christoph P. E. Zollikofer
Keyword(s):  
Common Ancestor ◽  
Great Apes ◽  
Last Common Ancestor

The Archaeology of Archaic and Early ModernHomo Sapiens: An African Perspective

1993 ◽  
Vol 3 (1) ◽  
pp. 21-39 ◽  
Author(s):  
Philip Allsworth-Jones
Keyword(s):  
Near East ◽  
Middle Stone Age ◽  
Stone Age ◽  
Upper Palaeolithic ◽  
Modern Humans ◽  
Anatomically Modern Humans ◽  
African Perspective ◽  
Out Of Africa

Whereas in Europe the transition from Middle to Upper Palaeolithic and the replacement of Neanderthal by anatomically modern humans appear to be synchronous events, in Africa this is not the case. Neanderthals as such were not present in Africa, and if the ‘Out of Africa’ model is correct, the ancestors of anatomically modern humans must have made their appearance in a Middle Stone Age context before 100,000 years ago. Subsequently, it seems that they coexisted with Neanderthals for up to 70,000 years in the Near East. If a direct biological correlation can be ruled out, the question arises: what was the impetus for an Upper Palaeolithic ‘revolution’ and why should it have taken place at all?

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