Ontogeny of locomotion in mouse lemurs: Implications for primate evolution
Grégoire Boulinguez-Ambroise1, Anthony Herrel1, Emmanuelle Pouydebat1
1UMR 7179-CNRS, National Museum of Natural History, 75321, Paris, Cedex 5, France.
Journal of Human Evolution
|March 16, 2020
Summary
Young primates develop strong grasping abilities early, enabling independent locomotion on challenging arboreal substrates. Their powerful grasps ensure stability, highlighting the evolutionary importance of hand and foot function in primate development.
Area of Science:
- Primate locomotion
- Developmental biology
- Evolutionary anatomy
Background:
- Juvenile primates face significant environmental challenges, including foraging and predator evasion, despite their immature physical state.
- Understanding early locomotor development is crucial for insights into primate evolution and selective pressures on young individuals.
Purpose of the Study:
- To explore developmental strategies for effective early locomotor abilities in juvenile primates.
- To investigate the evolution of primate locomotion through an ontogenetic lens.
Main Methods:
- An ontogenetic study of 36 arboreal gray mouse lemurs from birth to six months of age.
- Investigated limb grasping behavior (grip postures), grasping performance (pull strength), and motor coordination (rotarod test).
Main Results:
- Eight-day-old juveniles can climb various substrates; young individuals exhibit high relative pull strengths, ensuring stability on narrow surfaces.
- Motor coordination improves after 30 days, but powerful grasps are present from early life.
- Pedal grasping remains secure throughout development, while manual grasping decreases after early infancy, suggesting distinct limb functions.
Conclusions:
- Juvenile primates possess remarkable grasping abilities crucial for independent arboreal locomotion shortly after birth.
- Hind limbs primarily ensure balance, freeing forelimbs for manipulation, indicating functional differentiation.
- Challenging substrates like vertical and narrow branches likely drive the evolution of strong grasping in primates.
