Related Experiment Video
Updated: Jun 25, 2025
06:00
Experimental Manipulation of Body Size to Estimate Morphological Scaling Relationships in Drosophila
Published on: October 1, 2011
13.9K
Evolutionary-developmental (evo-devo) dynamics of hominin brain size.
1School of Biology, University of St Andrews, St Andrews, UK. mgf3@st-andrews.ac.uk.
Nature Human Behaviour
|May 27, 2024
Summary
Human brain expansion was not driven by direct selection, but by a genetic link to ovarian follicles. This surprising finding reveals how developmental constraints can shape evolution.
Area of Science:
- Evolutionary biology
- Developmental biology
- Paleoanthropology
Background:
- Hominin brain size tripled over four million years, but the drivers remain unclear.
- Understanding the evolutionary pressures behind brain expansion is crucial for human origins research.
Purpose of the Study:
- To mathematically model the evolutionary and developmental (evo-devo) dynamics of hominin brain size.
- To investigate the causal mechanisms behind the significant increase in hominin brain size.
Main Methods:
- Developed an evo-devo model incorporating brain and body size evolution for seven hominin species.
- Analyzed hominin brain-body allometry and key human developmental and evolutionary patterns.
Main Results:
- The model successfully reconstructed hominin brain and body size evolution and allometry.
- Brain expansion was not attributed to direct selection for larger brains.
- A genetic correlation with developmentally late preovulatory ovarian follicles was identified as the primary driver.
Conclusions:
- Developmental constraints, specifically genetic correlations, can drive the evolution of complex traits.
- Challenging ecologies and cumulative culture may facilitate the developmental conditions for such correlations.
- This suggests that the evolution of adaptive traits may be indirectly influenced by developmental processes rather than solely by direct selection.
Related Concept Videos
01:30Biological Influences on Intelligence
93
Intelligence is often thought to be linked to brain size, but the relationship is more complex than that. While brain size does correlate modestly with some abilities, like verbal skills, the connection is weaker for others, such as spatial reasoning. Other factors, like brain structure, also play crucial roles. For instance, despite Einstein's smaller-than-average brain, his parietal cortex, which is involved in spatial reasoning, was 15% wider, suggesting that neural density might matter...
93
02:31Synteny and Evolution
3.2K
John H. Renwick first coined the term “synteny” in 1971, which refers to the genes present on the same chromosomes, even if they are not genetically linked. The species with common ancestry tend to show conserved syntenic regions. Therefore, the concept of synteny is nowadays used to describe the evolutionary relationship between species.
Around 80 million years ago, the human and mice lineages diverged from the common ancestor. During the course of evolution, the ancestral...
Around 80 million years ago, the human and mice lineages diverged from the common ancestor. During the course of evolution, the ancestral...
3.2K
01:20Evolutionary Psychology
262
Evolutionary psychology explores the origins of human behavior and mental processes by framing them within the context of natural selection, a theory famously propounded by Charles Darwin. This field asserts that many behaviors common across human societies — ranging from instinctive fear reactions to complex social interactions — arose as evolutionary adaptations. These adaptations enhanced the survival and reproductive success of our ancestors, thereby becoming embedded in the...
262
02:55The Evidence for Evolution
42.7K
Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of novel varieties and entire new species. These changes are responsible for the diverse forms of life inhabiting the planet. The evidence for evolution suggests that all living organisms descended from common ancestors.
42.7K
01:54Convergent Evolution
27.7K
Evolution shapes the features of organisms over time, ensuring that they are suited for the environments in which they live. Sometimes, selection pressure leads to the rise of similar but unrelated adaptations in organisms with no recent common ancestors, a process known as convergent evolution.
27.7K
01:20Anatomy of the Brain: Major Regions
4.4K
The brain is the most complex organ in the human body. It consists of four main parts: the cerebrum, diencephalon, cerebellum, and brainstem.
The cerebrum is the largest section of the brain and divides into left and right hemispheres, separated by a deep fissure. The cerebral outer layer of grey matter — the cerebral cortex — comprises elevations called gyri and shallow groves called sulci. The inner portion of white matter includes long nerve fibers known as axons, which connect...
The cerebrum is the largest section of the brain and divides into left and right hemispheres, separated by a deep fissure. The cerebral outer layer of grey matter — the cerebral cortex — comprises elevations called gyri and shallow groves called sulci. The inner portion of white matter includes long nerve fibers known as axons, which connect...
4.4K