The Self-Domestication of Humans

Published on Feb 14, 2017
Ron Flannery presentation on the self domestication of humans – Darwin Day 2017 at Red Bank Humanists.

CARTA – Domestication and Human Evolution

about this series

The domestication of other species has played an undeniably central role in the evolution of modern humans, and in our planetary dominance and success. Researchers have over the years investigated the genetic underpinnings and the anatomical, neural, physiological and behavioral consequences of domestication across a number of animal species but largely independently of each other. Recently, a convergence of views has led to the notion that the study of animal domestication may tell us something not only about our relationship with domesticated species since perhaps at least the Pleistocene, but also about our own evolution as a species in the more distant past. This symposium brings together researchers from a variety of research backgrounds to examine these concepts and to elucidate further the possible role of domestication in human evolution.

CARTA: Domestication and Human Evolution: Introductory Remarks

Premiere Date: 12/12/2014; 17 minutes

UC San Diego’s Robert Kluender provides an excellent introductory overview of this symposium which addresses the study of animal domestication, our relationships with domesticated species, and what that might tell us about our own evolution as a species in the more distant past. Recorded on 10/10/2014.

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CARTA: Domestication and Human Evolution – Robert Wayne: The Transformation of Wolf to Dog: History, Traits, and Genetics

Premiere Date: 12/12/2014; 21 minutes

Robert Wayne (UCLA) presents a historical perspective on dog evolution in this talk. The timing and context of dog domestication is controversial. Wayne’s findings place domestication at a time when humans were migratory hunter-gatherers and suggest that a unique domestication scenario applies to the dog, the only large carnivore ever domesticated. Recorded on 10/10/2014.
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CARTA: Domestication and Human Evolution – Anna Kukekova: Fox Domestication and Genetics of Complex Behaviors

Premiere Date: 12/12/2014; 19 minutes

Anna Kukekova (Univ of Illinois at Urbana-Champaign) discusses the genetics-centered view of domestication that was supported by the experimental selection of farm-bred foxes (Vulpes vulpes) at the Russian Institute of Cytology and Genetics back in the 1950s. The selection of foxes, some for tame and some for aggressive behavior, yielded two strains with markedly different, genetically determined, behavioral phenotypes. These fox strains have provided a rich resource for investigating the genetics of complex social behaviors. Recorded on 10/10/2014.
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CARTA: Domestication and Human Evolution – Robert Franciscus: Craniofacial Feminization in Canine and Human Evolution

Premiere Date: 12/12/2014; 20 minutes

Robert Franciscus (Univ of Iowa) explains that anatomically modern humans are recognized in the fossil record primarily by retraction and diminution of the facial skeleton compared to pre-modern “archaic” humans. He then describes a promising model for the advent of facial diminution, which suggests that anatomically modern humans represent a ‘self-domesticated’ species where selection for increased social tolerance led to growth and developmental alterations producing craniofacial “feminization,” which itself results in a phenotypic signal of reduced aggressiveness. Recorded on 10/10/2014.
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CARTA: Domestication and Human Evolution – Terrence Deacon: The Domesticated Brain

Premiere Date: 12/12/2014; 21 minutes

In this talk Terrence Deacon (UC Berkeley) describes how the signature pattern of specific brain structure changes can provide evidence to distinguish between the processes associated with domestication. Recorded on 10/10/2014.
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CARTA: Domestication and Human Evolution – Philipp Khaitovich: Neotenous Gene Expression in the Developing Human Brain

Premiere Date: 12/12/2014; 19 minutes

Philipp Khaitovich (PICB, Shanghai) and his team have identified the human-specific delay in timing of neocortical synaptogenesis as one of the molecular mechanisms that potentially underlies the evolution of the human phenotype. Recorded on 10/10/2014.
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CARTA: Domestication and Human Evolution – Tecumseh Fitch: The Domestication Syndrome and Neural Crest Cells: A Unifying Hypothesis

Premiere Date: 12/12/2014; 20 minutes

The neural crest is a transitory embryonic tissue that, early in development, gives rise to a very diverse set of tissues and organs including pigment cells (melanocytes), bones, muscles and connective tissues in the head, and the adrenal gland. Tecumseh Fitch (Univ of Vienna) hypothesizes that the selection for tameness during early stages of domestication led to delayed maturation and reduced output of the adrenal component of the “fight or flight” response, via reduced neural crest input. This led, as an unselected byproduct, to other neural crest-derived tissues also being reduced, resulting in short snouts, smaller teeth, floppy ears, and changes in pigmentation (e.g. white spots). Recorded on 10/10/2014.
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CARTA: Domestication and Human Evolution – Kazuo Okanoya: Domestication and Vocal Behavior in Finches

Premiere Date: 12/12/2014; 16 minutes

Kazuo Okanoya (Univ of Tokyo) describes his research with Bengalese finches, a domesticated strain of wild white-rumped munias that were imported from China to Japan 250 years ago. He shows that evolution of song complexity involves not only factors related to sexual selection and species identification, but also to socio-emotional factors due to domestication. He then speculates that language evolution in humans might also be based on sexual selection and self-domestication. Recorded on 10/10/2014.
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CARTA: Domestication and Human Evolution – Richard Wrangham: Did Homo Sapiens Self-Domesticate?

Premiere Date: 12/12/2014; 21 minutes

In this talk Richard Wrangham (Harvard Univ) puts forth the theory that Homo sapiens are, in fact, a self-domesticated species. He defines “self-domestication” as the evolution of a reduced propensity for reactive aggression (compared to an immediate ancestor), without the active involvement of another species. He then shows that communal sanctions practiced by hunter-gatherers, which depend on proactive aggression, provide a leading candidate mechanism selecting against high levels of reactive aggression. He therefore proposes that human self-domestication is an ironic consequence of a particularly well-developed facility for proactive aggression, and concludes that humans did indeed self-domesticate, providing a critical underpinning for inter-individual tolerance and cooperation. Recorded on 10/10/2014.
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CARTA: Domestication and Human Evolution – Q&A and Closing Remarks

Premiere Date: 12/12/2014; 55 minutes

Closing remarks and Q&A for the symposium “Domestication and Human Evolution.” Recorded on 10/10/2014.

Further Resources

The “Domestication Syndrome” in Mammals: A Unified Explanation Based on Neural Crest Cell Behavior and Genetics

http://www.genetics.org/content/genetics/197/3/795.full.pdf

Adam S. Wilkins, Richard W. Wrangham and W. Tecumseh Fitch

GENETICS July 1, 2014 vol. 197 no. 3 795-808; https://doi.org/10.1534/genetics.114.165423

Abstract

Charles Darwin, while trying to devise a general theory of heredity from the observations of animal and plant breeders, discovered that domesticated mammals possess a distinctive and unusual suite of heritable traits not seen in their wild progenitors. Some of these traits also appear in domesticated birds and fish. The origin of Darwin’s “domestication syndrome” has remained a conundrum for more than 140 years. Most explanations focus on particular traits, while neglecting others, or on the possible selective factors involved in domestication rather than the underlying developmental and genetic causes of these traits. Here, we propose that the domestication syndrome results predominantly from mild neural crest cell deficits during embryonic development. Most of the modified traits, both morphological and physiological, can be readily explained as direct consequences of such deficiencies, while other traits are explicable as indirect consequences. We first show how the hypothesis can account for the multiple, apparently unrelated traits of the syndrome and then explore its genetic dimensions and predictions, reviewing the available genetic evidence. The article concludes with a brief discussion of some genetic and developmental questions raised by the idea, along with specific predictions and experimental tests.

Self-domestication in Homo sapiens: Insights from comparative genomics

Constantina Theofanopoulou, Simone Gastaldon, Thomas O’Rourke, Bridget D. Samuels, Angela Messner, Pedro Tiago Martins, Francesco Delogu, Saleh Alamri, Cedric Boeckx

Published: October 18, 2017 https://doi.org/10.1371/journal.pone.0185306

Abstract

This study identifies and analyzes statistically significant overlaps between selective sweep screens in anatomically modern humans and several domesticated species. The results obtained suggest that (paleo-)genomic data can be exploited to complement the fossil record and support the idea of self-domestication in Homo sapiens, a process that likely intensified as our species populated its niche. Our analysis lends support to attempts to capture the “domestication syndrome” in terms of alterations to certain signaling pathways and cell lineages, such as the neural crest.

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