What determines evolutionary brain growth?

2001 ◽  
Vol 24 (2) ◽  
pp. 278-279 ◽  
Author(s):  
Francisco Aboitiz
Keyword(s):  
Human Evolution ◽  
Brain Size ◽  
Processing Capacity ◽  
Brain Growth ◽  
Developmental Constraints ◽  
Size Evolution ◽  
Selection For

Finlay et al. address the importance of developmental constraints in brain size evolution. I discuss some aspects of this view such as the relation of brain size with processing capacity. In particular, I argue that in human evolution there must have been specific selection for increased processing capacity, and as a consequence for increased brain size.

scholarly journals Acrobatic Courtship Display Coevolves with Brain Size in Manakins (Pipridae)

2015 ◽  
Vol 85 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Willow R. Lindsay ◽  
Justin T. Houck ◽  
Claire E. Giuliano ◽  
Lainy B. Day
Keyword(s):  
Sexual Selection ◽  
Cognitive Abilities ◽  
Brain Size ◽  
Brain Evolution ◽  
Neural Systems ◽  
Motor Behaviour ◽  
Size Evolution ◽  
Complex Motor ◽  
Display Behaviour ◽  
Selection For

Acrobatic display behaviour is sexually selected in manakins (Pipridae) and can place high demands on many neural systems. Manakin displays vary across species in terms of behavioural complexity, differing in number of unique motor elements, production of mechanical sounds, cooperation between displaying males, and construction of the display site. Historically, research emphasis has been placed on neurological specializations for vocal aspects of courtship, and less is known about the control of physical, non-vocal displays. By examining brain evolution in relation to extreme acrobatic feats such as manakin displays, we can vastly expand our knowledge of how sexual selection acts on motor behaviour. We tested the hypothesis that sexual selection for complex motor displays has selected for larger brains across the Pipridae. We found that display complexity positively predicts relative brain weight (adjusted for body size) after controlling for phylogeny in 12 manakin species and a closely related flycatcher. This evidence suggests that brain size has evolved in response to sexual selection to facilitate aspects of display such as motor, sensorimotor, perceptual, and cognitive abilities. We show, for the first time, that sexual selection for acrobatic motor behaviour can drive brain size evolution in avian species and, in particular, a family of suboscine birds.

scholarly journals Chimpanzee and felid diet composition is influenced by prey brain size

2006 ◽  
Vol 2 (4) ◽  
pp. 505-508 ◽  
Author(s):  
Susanne Shultz ◽  
R.I.M Dunbar
Keyword(s):  
Diet Composition ◽  
Brain Size ◽  
Activity Patterns ◽  
Group Living ◽  
Chemical Defences ◽  
Size Evolution ◽  
Selection For ◽  
Specific Predator ◽  
Defence Strategies ◽  
Predator Defence

Prey use a wide variety of anti-predator defence strategies, including morphological and chemical defences as well as behavioural traits (risk-modulated habitat use, changes in activity patterns, foraging decisions and group living). The critical test of how effective anti-predator strategies are is to relate them to relative indices of mortality across predators. Here, we compare biases in predator diet composition with prey characteristics and show that chimpanzee ( Pan troglodytes ) and felid show the strongest and the most consistent predator bias towards small-brained prey. We propose that large-brained prey are likely to be more effective at evading predators because they can effectively alter their behavioural responses to specific predator encounters. Thus, we provide evidence for the hypothesis that brain size evolution is potentially driven by selection for more sophisticated and behaviourally flexible anti-predator strategies.

scholarly journals Dolphin social intelligence: complex alliance relationships in bottlenose dolphins and a consideration of selective environments for extreme brain size evolution in mammals

2007 ◽  
Vol 362 (1480) ◽  
pp. 587-602 ◽  
Author(s):  
Richard C Connor
Keyword(s):  
Cognitive Abilities ◽  
Social Intelligence ◽  
Brain Size ◽  
Bottlenose Dolphins ◽  
Sperm Whale ◽  
Shark Bay ◽  
External Threats ◽  
Size Evolution ◽  
Large Brain ◽  
Selection For

Bottlenose dolphins in Shark Bay, Australia, live in a large, unbounded society with a fission–fusion grouping pattern. Potential cognitive demands include the need to develop social strategies involving the recognition of a large number of individuals and their relationships with others. Patterns of alliance affiliation among males may be more complex than are currently known for any non-human, with individuals participating in 2–3 levels of shifting alliances. Males mediate alliance relationships with gentle contact behaviours such as petting, but synchrony also plays an important role in affiliative interactions. In general, selection for social intelligence in the context of shifting alliances will depend on the extent to which there are strategic options and risk. Extreme brain size evolution may have occurred more than once in the toothed whales, reaching peaks in the dolphin family and the sperm whale. All three ‘peaks’ of large brain size evolution in mammals (odontocetes, humans and elephants) shared a common selective environment: extreme mutual dependence based on external threats from predators or conspecific groups. In this context, social competition, and consequently selection for greater cognitive abilities and large brain size, was intense.

scholarly journals Linking brains and brawn: exercise and the evolution of human neurobiology

2013 ◽  
Vol 280 (1750) ◽  
pp. 20122250 ◽  
Author(s):  
David A. Raichlen ◽  
John D. Polk
Keyword(s):  
Physical Activity ◽  
Cognitive Performance ◽  
Human Evolution ◽  
Metabolic Regulation ◽  
Brain Size ◽  
Brain Growth ◽  
Aerobic Activity ◽  
Hunting And Gathering ◽  
Growth Factor Signalling ◽  
Signalling Compounds

The hunting and gathering lifestyle adopted by human ancestors around 2 Ma required a large increase in aerobic activity. High levels of physical activity altered the shape of the human body, enabling access to new food resources (e.g. animal protein) in a changing environment. Recent experimental work provides strong evidence that both acute bouts of exercise and long-term exercise training increase the size of brain components and improve cognitive performance in humans and other taxa. However, to date, researchers have not explored the possibility that the increases in aerobic capacity and physical activity that occurred during human evolution directly influenced the human brain. Here, we hypothesize that proximate mechanisms linking physical activity and neurobiology in living species may help to explain changes in brain size and cognitive function during human evolution. We review evidence that selection acting on endurance increased baseline neurotrophin and growth factor signalling (compounds responsible for both brain growth and for metabolic regulation during exercise) in some mammals, which in turn led to increased overall brain growth and development. This hypothesis suggests that a significant portion of human neurobiology evolved due to selection acting on features unrelated to cognitive performance.

scholarly journals Different environmental variables predict body and brain size evolution in Homo

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Manuel Will ◽  
Mario Krapp ◽  
Jay T. Stock ◽  
Andrea Manica
Keyword(s):  
Environmental Factors ◽  
Cognitive Abilities ◽  
Net Primary Productivity ◽  
Brain Size ◽  
Environmental Influence ◽  
Size Variation ◽  
Evolutionary Pattern ◽  
Statistical Framework ◽  
Size Evolution ◽  
Major Predictor

AbstractIncreasing body and brain size constitutes a key macro-evolutionary pattern in the hominin lineage, yet the mechanisms behind these changes remain debated. Hypothesized drivers include environmental, demographic, social, dietary, and technological factors. Here we test the influence of environmental factors on the evolution of body and brain size in the genus Homo over the last one million years using a large fossil dataset combined with global paleoclimatic reconstructions and formalized hypotheses tested in a quantitative statistical framework. We identify temperature as a major predictor of body size variation within Homo, in accordance with Bergmann’s rule. In contrast, net primary productivity of environments and long-term variability in precipitation correlate with brain size but explain low amounts of the observed variation. These associations are likely due to an indirect environmental influence on cognitive abilities and extinction probabilities. Most environmental factors that we test do not correspond with body and brain size evolution, pointing towards complex scenarios which underlie the evolution of key biological characteristics in later Homo.

Within and among plant variation in seed mass and pappus size in Tragopogon dubious

1989 ◽  
Vol 67 (5) ◽  
pp. 1298-1304 ◽  
Author(s):  
Mark A. McGinley
Keyword(s):  
Salt Lake ◽  
Salt Lake City ◽  
Seed Mass ◽  
Developmental Constraints ◽  
Position Effects ◽  
Plant Variation ◽  
Selection For ◽  
Lake City ◽  
Total Seed ◽  
Stalk Length

Individual seed mass of two seed morphs of Tragopogon dubious (L.) varied among plants and within and among flowering heads within individual plants growing near Salt Lake City, UT. Seeds of the light morph from the center of a receptacle were smaller than outer seeds, suggesting that variation in seed mass within heads was due to position effects. The total seed mass per head, seed number per head, and mean seed mass per head of both morphs declined in most plants over the season. Heads with larger total seed mass contained larger seeds both within and between plants so seasonal patterns in seed mass may be influenced by seasonal variation in the amount of resources available for investment in seeds. Seeds of the light colored morph had a greater dispersal potential than seeds from the dark colored morph because their disk loading was lower. Pappus size (both pappus radius and stalk length) increased with the number of seeds per head which may increase the efficiency of packaging fruits on the receptacle. Heads with a larger total seed mass allocated a smaller proportion of their resources to the dark seed morph which may serve to decrease the level of sibling competition experienced by the less dispersing seed morph. Thus, variation in investment in offspring may arise as a combination of developmental constraints and selection for variable investment.

Brain size evolution in small mammals: test of the expensive tissue hypothesis

Mammalia ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ying Jiang ◽  
Jia Yu Wang ◽  
Xiao Fu Huang ◽  
Chun Lan Mai ◽  
Wen Bo Liao
Keyword(s):  
Small Mammals ◽  
Brain Size ◽  
Reproductive Investment ◽  
Generalized Least Squares ◽  
Offspring Number ◽  
Size Evolution ◽  
Large Brain ◽  
Species Evolution ◽  
The Cost ◽  
Expensive Tissue Hypothesis

Abstract Brain size exhibits significant changes within and between species. Evolution of large brains can be explained by the need to improve cognitive ability for processing more information in changing environments. However, brains are among the most energetically expensive organs. Enlarged brains can impose energetic demands that limit brain size evolution. The expensive tissue hypothesis (ETH) states that a decrease in the size of another expensive tissue, such as the gut, should compensate for the cost of a large brain. We studied the interplay between energetic limitations and brain size evolution in small mammals using phylogenetically generalized least squares (PGLS) regression analysis. Brain mass was not correlated with the length of the digestive tract in 37 species of small mammals after correcting for phylogenetic relationships and body size effects. We further found that the evolution of a large brain was not accompanied by a decrease in male reproductive investments into testes mass and in female reproductive investment into offspring number. The evolution of brain size in small mammals is inconsistent with the prediction of the ETH.

On Diet, Energy Metabolism, and Brain Size in Human Evolution

1996 ◽  
Vol 37 (1) ◽  
pp. 125-129 ◽  
Author(s):  
William R. Leonard ◽  
Marcia L. Robertson ◽  
Leslie C. Aiello ◽  
Peter Wheeler
Keyword(s):  
Energy Metabolism ◽  
Human Evolution ◽  
Brain Size

Brain size evolution in the frog Fejervarya limnocharis supports neither the cognitive buffer nor the expensive brain hypothesis

2016 ◽  
Vol 302 (1) ◽  
pp. 63-72 ◽  
Author(s):  
C. L. Mai ◽  
J. Liao ◽  
L. Zhao ◽  
S. M. Liu ◽  
W. B. Liao
Keyword(s):  
Brain Size ◽  
Size Evolution ◽  
Fejervarya Limnocharis

Constraints on Social Networks

2010 ◽  
Author(s):  
Sam G. B. Roberts
Keyword(s):  
Social Networks ◽  
Social Relationships ◽  
Human Evolution ◽  
Upper Bound ◽  
Brain Size ◽  
Network Approach ◽  
Cognitive Constraints ◽  
Hominin Evolution ◽  
Over Time ◽  
Size And Structure

In both modern humans and non-human primates, time and cognitive constraints place an upper bound on the number of social relationships an individual can maintain at a given level of intensity. Similar constraints are likely to have operated throughout hominin evolution, shaping the size and structure of social networks. One of the key trends in human evolution, alongside an increase in brain size, is likely to have been an increase in group size, resulting in a larger number of social relationships that would have to be maintained over time. The network approach demonstrates that relationships should not be viewed as dyadic ties between two individuals, but as embedded within a larger network of ties between network members. Together with relationships based on kinship, this may have allowed for larger groups to be maintained among hominins than would be possible if such networks were based purely on dyadic ties between individuals.

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