Demic expansions and human evolution

Science ◽  
1993 ◽  
Vol 259 (5095) ◽  
pp. 639-646 ◽  
Author(s):  
LL Cavalli-Sforza ◽  
P Menozzi ◽  
A Piazza
Keyword(s):  
Genetic Differentiation ◽  
Human Evolution ◽  
Genetic Drift ◽  
Modern Human ◽  
Human Populations ◽  
Random Genetic Drift ◽  
Population Densities ◽  
Local Growth ◽  
The Earth ◽  
Spread Of Agriculture

Geographic expansions are caused by successful innovations, biological or cultural, that favor local growth and movement. They have had a powerful effect in determining the present patterns of human genetic geography. Modern human populations expanded rapidly across the Earth in the last 100,000 years. At the end of the Paleolithic (10,000 years ago) only a few islands and other areas were unoccupied. The number of inhabitants was then about one thousand times smaller than it is now. Population densities were low throughout the Paleolithic, and random genetic drift was therefore especially effective. Major genetic differences between living human groups must have evolved at that time. Population growths that began afterward, especially with the spread of agriculture, progressively reduced the drift in population and the resulting genetic differentiation. Genetic traces of the expansions that these growths determined are still recognizable.

Alternative models of Pleistocene biocultural evolution: a response to Foley

Antiquity ◽  
1989 ◽  
Vol 63 (238) ◽  
pp. 153-159 ◽  
Author(s):  
G. A. Clark
Keyword(s):  
Human Evolution ◽  
Modern Human ◽  
Human Populations ◽  
Human Origins ◽  
Single Source ◽  
Recent Discussion ◽  
Garden Of Eden ◽  
Biocultural Evolution ◽  
History Of ◽  
Origins Research

Human origins research has had a long history of vigorous debate. Recent discussion has been no exception, the more so perhaps as the strands of evidence — anthropological, archaeological, and now molecular-biological — are sufficiently diverse that not many can be well placed to deal fairly with them all. Here issue is taken with Foley's cladistic view of human evolution, and with the ‘Garden of Eden’ hypothesis of a single source in Africa for modern human populations.

scholarly journals Something old, something borrowed: Admixture and adaptation in human evolution

2018 ◽  
Author(s):  
Michael Dannemann ◽  
Fernando Racimo
Keyword(s):  
Human Evolution ◽  
Ancient Dna ◽  
Gene Pool ◽  
Recent Literature ◽  
Genetic Material ◽  
Modern Human ◽  
Human Populations ◽  
Modern Humans ◽  
Functional Assays ◽  
Over Time

Almost a decade ago, the sequencing of ancient DNA from archaic humans - Neanderthals and Denisovans - revealed that modern and archaic humans interbred at least twice during the Pleistocene. The field of human paleogenomics has now turned its attention towards understanding the nature of this genetic legacy in the gene pool of present-day humans. What exactly did modern humans obtain from interbreeding with Neanderthals and Denisovans? Were introgressed genetic material beneficial, neutral or maladaptive? Can differences in phenotypes among present-day human populations be explained by archaic human introgression? These questions are of prime importance for our understanding of recent human evolution, but will require careful computational modeling and extensive functional assays before they can be answered in full. Here, we review the recent literature characterizing introgressed DNA and the likely biological consequences for their modern human carriers. We focus particularly on archaic human haplotypes that were beneficial to modern humans as they expanded across the globe, and on ways to understand how populations harboring these haplotypes evolved over time.

scholarly journals Something old, something borrowed: Admixture and adaptation in human evolution

2018 ◽  
Author(s):  
Michael Dannemann ◽  
Fernando Racimo
Keyword(s):  
Human Evolution ◽  
Ancient Dna ◽  
Gene Pool ◽  
Recent Literature ◽  
Genetic Material ◽  
Modern Human ◽  
Human Populations ◽  
Modern Humans ◽  
Functional Assays ◽  
Over Time

Almost a decade ago, the sequencing of ancient DNA from archaic humans - Neanderthals and Denisovans - revealed that modern and archaic humans interbred at least twice during the Pleistocene. The field of human paleogenomics has now turned its attention towards understanding the nature of this genetic legacy in the gene pool of present-day humans. What exactly did modern humans obtain from interbreeding with Neanderthals and Denisovans? Were introgressed genetic material beneficial, neutral or maladaptive? Can differences in phenotypes among present-day human populations be explained by archaic human introgression? These questions are of prime importance for our understanding of recent human evolution, but will require careful computational modeling and extensive functional assays before they can be answered in full. Here, we review the recent literature characterizing introgressed DNA and the likely biological consequences for their modern human carriers. We focus particularly on archaic human haplotypes that were beneficial to modern humans as they expanded across the globe, and on ways to understand how populations harboring these haplotypes evolved over time.

scholarly journals Relationship between the genetic structure of human populations and geographical and climatic parameters

2018 ◽  
pp. 37-40
Author(s):  
А.А. Попович ◽  
К.В. Вагайцева ◽  
А.В. Бочарова ◽  
В.А. Степанов
Keyword(s):  
Genetic Diversity ◽  
Modern Human ◽  
Cold Climate ◽  
Human Populations ◽  
Genetic Constitution ◽  
Nucleotide Polymorphisms ◽  
Climatic Parameters ◽  
Single Nucleotide ◽  
Variability Analysis ◽  
The Earth

Популяции человека проживают в различных условиях среды обитания, которые требуют адаптации, особенно к экстремальным средовым факторам. Действие адаптивной эволюции отражается и на генетической структуре популяций человека. В настоящем исследовании был проведен анализ вариабельности 25 однонуклеотидных полиморфизмов (SNP), связанных с адаптацией к холодному климату, в мировых популяциях. Показано влияние климатических и географических факторов на генетическое разнообразие популяций человека. Выявлен рост генетического разнообразия по изученным маркерам от Африки по мере расселения современного человека по земному шару. Вероятно, высокая частота аллелей, ассоциированных с адаптацией к климату, в некоторых популяциях человека может быть объяснена в рамках гипотезы канализации/деканализации геном-феномных отношений в ходе расселения современного человека. Human populations live in different environmental conditions that require adaptation, especially to extreme environmental factors. The action of adaptive evolution is also reflected on human populations’ genetic constitution. The study highlights the variability analysis of 25 SNPs single nucleotide polymorphisms (SNP) related to adaptation to a cold climate, as well as influence of climatic and geographical factors on the genetic diversity of human populations. The growth of the genetic diversity among the studied markers from Africa according to a modern human’s displacement around the earth identified. Probably, the variability of alleles associated with adaptation to climate in some populations could be explained in the framework of the hypothesis of canalization/decanalization of genome-phenome relationships under natural selection during modern human dispersion.

scholarly journals Detecting Ancient Admixture in Humans Using Sequence Polymorphism Data

Genetics ◽  
2000 ◽  
Vol 154 (3) ◽  
pp. 1271-1279 ◽  
Author(s):  
Jeffrey D Wall
Keyword(s):  
Human Evolution ◽  
Sequence Data ◽  
Modern Human ◽  
Sequence Polymorphism ◽  
Parameter Estimates ◽  
Human Populations ◽  
Ancient Population ◽  
Single Origin ◽  
Polymorphism Data ◽  
Nuclear Loci

Abstract A debate of long-standing interest in human evolution centers around whether archaic human populations (such as the Neanderthals) have contributed to the modern gene pool. A model of ancient population structure with recent mixing is introduced, and it is determined how much information (i.e., sequence data from how many unlinked nuclear loci) would be necessary to distinguish between different demographic scenarios. It is found that ~50–100 loci are necessary if plausible parameter estimates are used. There are not enough data available at the present to support either the “single origin” or the “multiregional” model of modern human evolution. However, this information should be available in a few years.

Analysis of Human Evolution Under Random Genetic Drift

1964 ◽  
Vol 29 (0) ◽  
pp. 9-20 ◽  
Author(s):  
L. L. Cavalli-Sforza ◽  
I. Barrai ◽  
A. W. F. Edwards
Keyword(s):  
Human Evolution ◽  
Genetic Drift ◽  
Random Genetic Drift

scholarly journals Something old, something borrowed: Admixture and adaptation in human evolution

2018 ◽  
Author(s):  
Michael Dannemann ◽  
Fernando Racimo
Keyword(s):  
Human Evolution ◽  
Ancient Dna ◽  
Gene Pool ◽  
Recent Literature ◽  
Genetic Material ◽  
Modern Human ◽  
Human Populations ◽  
Modern Humans ◽  
Functional Assays ◽  
Over Time

Almost a decade ago, the sequencing of ancient DNA from archaic humans - Neanderthals and Denisovans - revealed that modern and archaic humans interbred at least twice during the Pleistocene. The field of human paleogenomics has now turned its attention towards understanding the nature of this genetic legacy in the gene pool of present-day humans. What exactly did modern humans obtain from interbreeding with Neanderthals and Denisovans? Were introgressed genetic material beneficial, neutral or maladaptive? Can differences in phenotypes among present-day human populations be explained by archaic human introgression? These questions are of prime importance for our understanding of recent human evolution, but will require careful computational modeling and extensive functional assays before they can be answered in full. Here, we review the recent literature characterizing introgressed DNA and the likely biological consequences for their modern human carriers. We focus particularly on archaic human haplotypes that were beneficial to modern humans as they expanded across the globe, and on ways to understand how populations harboring these haplotypes evolved over time.

Rapid, Adaptive Human Evolution Facilitated by Admixture in the Americas

2021 ◽  
pp. 122-138
Author(s):  
Emily T. Norris ◽  
Lavanya Rishishwar ◽  
I. King Jordan
Keyword(s):  
Human Evolution ◽  
Adaptive Evolution ◽  
Modern Human ◽  
Human Migration ◽  
Human Populations ◽  
Human Immune System ◽  
Isolated Populations ◽  
Adaptive Introgression ◽  
Physical Isolation ◽  
Source Populations

Humans have migrated from their ancestral homelands in Africa to nearly every part of the world. Human migration is characterized by a recurrent process of physical isolation and genetic diversification followed by admixture, whereby previously isolated populations come together and exchange genes. Admixture results in the introgression of alleles from ancestral source populations into hybrid admixed populations, and introgression can facilitate rapid, adaptive evolution by introducing beneficial alleles at intermediate frequencies. We provide examples of adaptive introgression between archaic and modern human populations and for admixed populations in the Americas, which were formed relatively recently via admixture among African, European, and Indigenous American ancestral populations. Adaptive introgression has had an outsized effect on the human immune system. In light of the ubiquity of admixture in human evolution, we propose that adaptive introgression is a fundamentally important mechanism for driving rapid, adaptive evolution in human populations.

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