On the Time Scale of Human Evolution: Evidence for Recent Adaptive Evolution

On the Time Scale of Human Evolution: Evidence for Recent Adaptive Evolution (full d.)

Gerhard Meisenberg (2008)

Abstract

To what extent did the genetic constitution of human population change in the recent past, and how fast are evolutionary changes proceeding in present-day populations? This review summarizes the available evidence about genetic adaptations that evolved after the dispersal of modern humans from Africa about 50,000 years ago and especially since the Neolithic Revolution and the emergence of the first civilizations. Evidence for recent evolutionary change is obtained from the molecular study of individual genes that have been or are currently under selection, and genomic studies that identify genomic regions under recent or ongoing adaptive evolution. The molecular evidence is complemented by archaeological evidence about population dispersals and prehistoric living conditions, and by evidence from historical demography about differential fertility and mortality in historic populations. The conclusion is that evidence for recent adaptive evolution is overwhelming, in many cases at the level of individual genes. There is also evidence that in many cases the selection of adaptive traits occurred in recent historic times. These adaptations evolved in response to climatic conditions, the nutritional changes brought about by the introduction of settled farming, exposure to new diseases, and the social conditions of civilized life. There is evidence that compared to earlier times, human adaptive evolution has accelerated massively since the Neolithic Revolution, possibly by a factor of about 100. Because historic and evolutionary time scales overlap, gene-culture coevolution is emerging as a major unifying theme in anthropological research.

Life history traits of humans compared with chimpanzees:

(full size: click at the image)














Source:
Patterns and processes of human life history evolution. MP Muehlenbein & MV Flinn; 2011

All One Species?

http://westhunt.wordpress.com/2013/10/18/all-one-species-2/

Paternal provisioning versus mate seeking in human populations

Paternal provisioning versus mate seeking in human populations
Edward M Miller; August 1994
Personal and Individual Differences


Abstract

Paternal investment theory suggests that, in cold climates males were selected for provisioning, rather than for mating success. In warm climates, where female gathering made male provisioning unessential, selection was for mating success. Male hunted meat was essential for female winter survival. Genes that encouraged mating success were selected for in cold climates. Negroids (blacks) evolved in cold climates, while Caucasians (whites) and Mongoloids (Asians) evolved in colder climates. Mating is assisted by a strong sex drive, aggression, dominance, sociability, extraversion, impulsiveness, sensation seeking, and high testosterone. Provisioning is assisted by anxiety, altruism, empathy, behavioral restraint, gratification delay, and a long life span. Explanations are offered for racial differences in many personality characteristics, hormone levels, monamine oxidase levels, testosterone levels, lactase dehydrogenase metabolic paths, life spans, prostate cancer rates, hypertension, genital (penis and testes) size, vocal frequencies, liver size, muscle structure, mesomorphy, bone density, sports performance, crime rates, rape, child abuse, earnings, age at first sexual activity. AIDs, illegitimacy, divorce, marriage, and polygyny rates. Eye color correlations are discussed. Negro family structure in the Caribbean and the U.S. may reflect selection in Africa during hunter-gather times. Comparison is made with differential K theory and father absence theories.

[ full article (Google Scholar)]

Foraging and farming as niche construction: stable and unstable adaptations

Foraging and farming as niche construction: stable and unstable adaptations
Peter Rowly-Conwy and Robert Layton; 2011
http://rstb.royalsocietypublishing.org/content/366/1566/849.long


Abstract

All forager (or hunter–gatherer) societies construct niches, many of them actively by the concentration of wild plants into useful stands, small-scale cultivation, burning of natural vegetation to encourage useful species, and various forms of hunting, collectively termed ‘low-level food production’. Many such niches are stable and can continue indefinitely, because forager populations are usually stable. Some are unstable, but these usually transform into other foraging niches, not geographically expansive farming niches. The Epipalaeolithic (final hunter–gatherer) niche in the Near East was complex but stable, with a relatively high population density, until destabilized by an abrupt climatic change. The niche was unintentionally transformed into an agricultural one, due to chance genetic and behavioural attributes of some wild plant and animal species. The agricultural niche could be exported with modifications over much of the Old World. This was driven by massive population increase and had huge impacts on local people, animals and plants wherever the farming niche was carried. Farming niches in some areas may temporarily come close to stability, but the history of the last 11 000 years does not suggest that agriculture is an effective strategy for achieving demographic and political stability in the world's farming populations.

Evolution of lactase persistence: an example of human niche construction

Evolution of lactase persistence: an example of human niche construction
Pascale Gerbault et al.; 2011
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3048992/


Abstract

Niche construction is the process by which organisms construct important components of their local environment in ways that introduce novel selection pressures. Lactase persistence is one of the clearest examples of niche construction in humans. Lactase is the enzyme responsible for the digestion of the milk sugar lactose and its production decreases after the weaning phase in most mammals, including most humans. Some humans, however, continue to produce lactase throughout adulthood, a trait known as lactase persistence. In European populations, a single mutation (−13910*T) explains the distribution of the phenotype, whereas several mutations are associated with it in Africa and the Middle East. Current estimates for the age of lactase persistence-associated alleles bracket those for the origins of animal domestication and the culturally transmitted practice of dairying. We report new data on the distribution of −13910*T and summarize genetic studies on the diversity of lactase persistence worldwide. We review relevant archaeological data and describe three simulation studies that have shed light on the evolution of this trait in Europe. These studies illustrate how genetic and archaeological information can be integrated to bring new insights to the origins and spread of lactase persistence. Finally, we discuss possible improvements to these models.

The cognitive niche: Coevolution of intelligence, sociality, and language

The cognitive niche: Coevolution of intelligence, sociality, and language
Steven Pinker; 2010


Abstract

Although Darwin insisted that human intelligence could be fully explained by the theory of evolution, the codiscoverer of natural selection, Alfred Russel Wallace, claimed that abstract intelligence was of no use to ancestral humans and could only be explained by intelligent design. Wallace’s apparent paradox can be dissolved with two hypotheses about human cognition. One is that intelligence is an adaptation to a knowledge-using, socially interdependent lifestyle, the “cognitive niche.” This embraces the ability to overcome the evolutionary fixed defenses of plants and animals by applications of reasoning, including weapons, traps, coordinated driving of game, and detoxification of plants. Such reasoning exploits intuitive theories about different aspects of the world, such as objects, forces, paths, places, states, substances, and other people’s beliefs and desires. The theory explains many zoologically unusual traits in Homo sapiens, including our complex toolkit, wide range of habitats and diets, extended childhoods and long lives, hypersociality, complex mating, division into cultures, and language (which multiplies the benefit of knowledge because know-how is useful not only for its practical benefits but as a trade good with others, enhancing the evolution of cooperation). The second hypothesis is that humans possess an  ability of metaphorical abstraction, which allows them to coopt faculties that originally evolved for physical problem-solving and social coordination, apply them to abstract subject matter, and combine them productively. These abilities can help explain the emergence of abstract cognition without supernatural or exotic evolutionary forces and are in principle testable by analyses of statistical signs of selection in the human genome.

Human nature or human natures?

Human nature or human natures?
Peter Frost; 2011


Abstract

Most evolutionary psychologists share a belief in one key concept: the environment of evolutionary adaptedness (EEA), i.e., the ancestral environment that shaped the heritable mental and behavioral traits of present-day humans. It is usually placed in the African savannah of the Pleistocene, long before our ancestors began to spread to other continents some fifty thousand years ago. Thus, later environments have not given rise to new traits through genetic evolution.

This belief rests on two arguments: 1) such traits are complex and therefore evolve too slowly to have substantially changed over the past fifty thousand years; 2) because the same time frame has seen our species diversify into many environments, recent traits should tend to be environment-specific and hence population-specific, yet such specificity  seems inconsistent with the high genetic overlap among human populations. Both arguments are weaker than they seem. New complex traits can arise over a relatively short time through additions, deletions, or modifications to existing complex traits, and genetic overlap can be considerable even between species that are morphologically, behaviorally, and physiologically distinct.

There is thus no conceptual barrier to the existence of EEAs in post-Pleistocene times. Such a paradigm could shed light on such research topics as the visual word form area, reproductive strategy, predisposition to violence among young men, and personality traits. Eventually, a multi-EEA model may dominate evolutionary psychology, perhaps after an interim period of accommodation with the current model.

[See also: http://www.humanbiologicaldiversity.com/]

The human socio-cognitive niche and its evolutionary origins

The human socio-cognitive niche and its evolutionary origins
Andrew Withen & David Erdal; 2012
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3385679/


Abstract

Hominin evolution took a remarkable pathway, as the foraging strategy extended to large mammalian prey already hunted by a guild of specialist carnivores. How was this possible for a moderately sized ape lacking the formidable anatomical adaptations of these competing ‘professional hunters’? The long-standing answer that this was achieved through the elaboration of a new ‘cognitive niche’ reliant on intelligence and technology is compelling, yet insufficient. Here we present evidence from a diversity of sources supporting the hypothesis that a fuller answer lies in the evolution of a new socio-cognitive niche, the principal components of which include forms of cooperation, egalitarianism, mindreading (also known as ‘theory of mind’), language and cultural transmission, that go far beyond the most comparable phenomena in other primates. This cognitive and behavioural complex allows a human hunter–gatherer band to function as a unique and highly competitive predatory organism. Each of these core components of the socio-cognitive niche is distinctive to humans, but primate research has increasingly identified related capacities that permit inferences about significant ancestral cognitive foundations to the five pillars of the human social cognitive niche listed earlier. The principal focus of the present study was to review and integrate this range of recent comparative discoveries.

Veröffentlichungen von R.D. Alexander über die Humanevolution:

HOW DID HUMANS EVOLVE?, R.D. Alexander, 1990
http://courses.washington.edu/evpsych/Alexander%20-%20How%20did%20humans%20evolve%20-%201990.pdf

EVOLUTION OF THE HUMAN PSYCHE, R.D. Alexander, 1989
http://qcpages.qc.edu/Biology/LahtiSites/RDAlexander/Pubs/Alexander89.pdf
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Übersicht der Veröffentlichungen:
http://qcpages.qc.edu/Biology/LahtiSites/RDAlexander/publications.html#proarticles
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Darwinism and Philosophy, 2005
http://qcpages.qc.edu/Biology/LahtiSites/RDAlexander/Pubs/Alexander05.pdf

Social Aspects of Human Evolution:

The most unpredictable and demanding aspects of the environment of evolving humans have always been its social aspects, not the physical climate or food shortages as often implied. The human psyche was designed primarily to solve social problems within its own species, not physical and mathematical puzzles, as educational tests and some concerns of philosophers might cause us to believe. ... This hypothesis implies that even the solving of mathematical, physical, and nunhuman biotic problems had its central significance (in the broadest sense, its reproductive rewards) in social contexts. ...

Evolution of the Human Psyche (1989), Richard D. Alexander

Evolution of the Human Psyche:

Evolution of the Human Psyche (1989),
Richard D. Alexander

http://qcpages.qc.edu/Biology/LahtiSites/RDAlexander/Pubs/Alexander89.pdf