Limits of brain size & muscle contraction and the superpower of infants | Last Week in Science (14 Jul 2024)

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Superpower of 12 month old babies

Credit: Peter Lengyel-Szabo

What does it mean to be creative?  It can be defined as creating new ideas by combining different kinds of concepts and information using one's imagination. We had not known until now as to when creative thinking begins. Researchers at Birmingham University & Central European University have found that it begins as early as 1 year of age even before the baby learns to speak.

Researchers worked with twelve month old infants who had not started to speak yet and could understand a few words. In the first part of the experiment they taught the infants two made up words which represented quantity - 'mize' for one object and 'padu' for two. In the second part the infants were shown four different sets of objects - one duck, two ducks, one ball, & two balls and the researchers would say a phrase like - 'padu ducks'. They observed that the infant would look at the set of two ducks for long as compared to the other three sets of objects when the phrase - 'padu ducks' was said.

Researchers suggest that infants as old as 12 months can combine different concepts like quantity and kind - one or two with different kinds of objects. This indicates the ability to combine different concepts to create new ideas. They further suggest that this creative thinking could be needed for learning language that they hear around them and in making sense of their environment which helps them in learning fast.



Not so large brains

Does the brain size increases as the size of the body increases in the animal kingdom? Logic says it should but that is not the case. The largest sized animals do not have a proportionally large brain. Researchers at  the University of Reading and Durham University have constructed a model to explain this anomaly in brain size evolution statistically at least.

The researchers studied brain and body size of 1500 different species to develop their model. The model suggests that the brain size does not increase proportionally with the body size, i.e. the relationship cannot be represented by a line but is instead seen as a curve. And this curve would suggest that the largest animals would not have as large brains as expected.

Some of the animal groups that are responsible for causing this trend are - primates that includes humans, rodents, and carnivores. They further found that the brain size increased much faster in these animals as they evolved in comparison to other animals. For example when we look at evolution of humans the brain size increased 20 times faster than all other mammalian species as the size of humans increased during evolution.

The researchers suggest that it needs to be studied why the rate of increase in the size of brain had been different for different species. This would help in understanding the restrictions that evolution has put on the size of the brain in different animals.

Reference: Brain size riddle solved as humans exceed evolution trend


Soft machines

A large proportion of the body of animals is made up of water and so are the muscles. Scientists at the University of Michigan and Harvard University have described muscles as active water filled sponges that convert chemical energy into movement just like an engine, calling it as a soft engine.

The brain controls the movement of muscles which contract and relax alternately to make movement of cells and body possible. Different proteins makes this movement possible and this protein machinery of the muscle is submerged in water.

In this study, the muscles that cause very fast movements were studied to understand what restricts the movement of a muscle beyond a certain speed. The scientists found that muscles like the ones in the tail of rattlesnake that move 10 to 100 times per second can be directly controlled by neurons to achieve this speed. But it is not possible for neurons to directly achieve muscle movement of 100 to 1000 times per second as in the wing muscles of insects when they fly.

Scientists developed a model to understand such fast movements. They found that the movement of water in the muscles can create high speeds of muscle contractions. So, muscle can be seen as an active sponge filled with water that contracts in length and squeezes to power movement of cells and body. The model also suggests that the movement of water inside the muscles puts a limit on how fast a muscle can contract.


Reference: Muscle machine: How water controls the speed of muscle contraction

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