Evolution du cerveau

L’évolution du cerveau humain pose une multitude de questions. Sa chronologie, ses causes, ses facteurs limitants, ses conséquences…
Elle est liée notamment à la controverse « du feu ou de la viande » exposée dans cet article et les suivants, et plus succinctement dans ce thread twitter.

1. Données sur l’évolution du cerveau humain
2. Déterminants de l’évolution du cerveau

Données sur l’évolution du cerveau humain

Pattern and process in hominin brain size evolution are scale-dependent
Andrew Du et al.
The Royal Society Publishing, 2018
Our results show that fossil hominin ECV data at the clade level are most consistent with a gradual pattern of ECV increase through time. Understanding how this pattern emerged from processes that operate at lower taxonomic levels is more com-
plicated. Our analyses are consistent with microevolutionary mechanisms as the dominant driver of clade-level change (64 or 88% of change using a more or less speciose taxonomy, respectively), alternating with secondary macroevolutionary
mechanisms. This implies changing selective pressures and shifts in the relative importance of different evolutionary processes through time.
Les créationnistes aussi planchent sur l’évolution du cerveau :
Estimating the statistical significance of hominin encephalization
TC Wood.
Journal of creation theology and science, 2016
Brain ontogeny and life history in Pleistocene hominins
Jean-Jacques Hublin et al.
The Royal Society Publishing, 2015
There is a consensus that Australopithecus endocasts show signs of brain reorganization and depart from the sulcal patterns found in apes, despite their ape-like endocranial volumes. It is therefore possible that brain reorganization in australopiths and its cognitive consequences underlie the subsequent brain expansion in the genus Homo. Furthermore, if supported by further investigations, the protracted pattern of brain development in A. afarensis would confirm that one cannot simply contrast a primitive ‘ape-pattern’ to a ‘human-pattern’.
Scaling of brain and body weight within modern and fossil hominids:
implications for the Flores specimen
The relationship between encephalization quotient (EQ) and body weight
is found to be consistently negative within all hominid species
Une première augmentation significative de l’encéphalisation avant -1,8Ma suivie d’un plateau, puis d’une seconde augmentation significative entre -600 et -150ka. L’une initiée par le passage à l’alimentation carnée, l’autre permise par le feu ?
Body mass and encephalization in pleistocene Homo
Ruff et al.
Nature, 1997

On the basis of an analysis of 163 individuals, body mass in Pleistocene Homo averaged significantly (about 10%) larger than a representative sample of living humans. Relative to body mass, brain mass in late archaic H. sapiens (Neanderthals) was slightly smaller than in early ‘anatomically modern’ humans, but the major increase in encephalization within Homo occurred earlier during the Middle Pleistocene (600–150 thousand years before present (kyr BP)), preceded by a long period of stasis extending through the Early Pleistocene (1,800 kyr BP).

Déterminants de l’évolution du cerveau

Evolution of the Human Brain: the key roles of DHA (omega-3 fatty acid) and Δ6-desaturase gene
Didier Majou
Oilseeds and fat crops and lipids, 2018
How scientists perceive the evolutionary origin of human traits: Results of a survey study

Hanna Tuomisto et al.
Ecology and evolution, 2018

The hypotheses proposing that encephalization was triggered by improved nutrition also received intermediate popularity scores, whether achieved by cooking or by increased consumption of fish or meat (all three with credibility scores in the range 2.61–2.77).

The evolutionary roles of nutrition selection and dietary quality in the human brain size and encephalization
Roberto Carlos Burini, William R. Leonard
Nutrire, 2018


In addition to the energetic benefits associated with greater meat consumption, it appears that such a dietary shift would have also provided increased levels of key fatty acids necessary for supporting the rapid hominid brain evolution [60].

Half of human brain composition is fat, and 20% of its dry weight is long-chain polyunsaturated fatty acids (LCPUFAs). Consequently, improvements in consumption of dietary fat were a necessary condition for promoting encephalization [61, 62].

Mammalian brain growth is dependent upon sufficient amounts of two LCPUFAs: docosahexaenoic acid (DHA) and arachidonic acid (AA), and it appears that mammals have a limited capacity to synthesize these fatty acids from dietary precursors. Hence, species with higher levels of encephalization would have greater requirements for DHA and AA [62]. Consequently, dietary sources of DHA and AA were likely limiting nutrients that constrained the evolution of larger brain size in many mammalian lineages [63].

Meat and Nicotinamide: A Causal Role in Human Evolution, History, and Demographics
Adrian C Williams, Lisa J Hill
International Journal of Tryptophan Research, 2017
Control of Fire in the Paleolithic: Evaluating the Cooking Hypothesis
Richard Wrangham, 2017
Human Brain Expansion during Evolution Is Independent of Fire Control and Cooking
Alianda M. Cornelio et al.
Frontiers in neurosciences, 2016.
Brain size and thermoregulation during the evolution of the genus Homo
Daniel E. Naya et al.
Comparative biochemistry and physiology, 2016
Metabolic costs and evolutionnary implications of human brain development
Kuzawa et al.
Proceedings of the national academy of science, 2014
We find that the brain’s metabolic requirements peak in childhood, when it uses glucose at a rate equivalent to 66% of the body’s resting metabolism and 43% of the body’s daily energy requirement, and that brain glucose demand relates inversely to body growth from infancy to puberty. Our findings support the hypothesis that the unusually high costs of human brain development require a compensatory slowing
of childhood body growth.
Docosahexaenoic Acid and Shore-Based Diets in Hominin Encephalization: A Rebuttal
Cunnane et al.
American journal of human biology, 2007
The Critical Role Played by Animal Source Foods in Human (Homo) Evolution
Katharine Milton, 2003

The expensive-tissue hypothesis : the brain and the digestive system in human and primate evolution. Leslie Aiello, Peter Wheeler, 1995.

Sur le rôle de l’alimentation dans l’évolution du cerveau, mais ici, plutôt les fruits, et pour les primates non humains (les humains sont exclus parce que la taille de leur cerveau est trop atypique) :
Primate brain size is predicted by diet but not sociality
Alex R. DeCasien et al.


Graphique évolution du cerveau et acquisitions culturelles humaines
Bradshaw foundation, 2012, pour le visuel original.