Do ecologists have to read the work of Einstein? Yes, it appears! Einstein’s theory with which he explained Brownian motion in molecules is equally valid for animals. This is the result of the work of Monique de Jager, one of my PhD students, and has just appeared in the Proceedings of Royal Society B.

See here a direct link: http://rspb.royalsocietypublishing.org/content/281/1774/20132605.full.pdf

Mussels confirm theory Albert Einstein

Mussels in dense mussel beds move in a similar fashion as molecules. Hereby, they confirm the theory for Brownian motion proposed by Albert Einstein in 1905. Monique de Jager of the NIOZ Royal Netherlands Institute of Sea Research explains the movements of mussels in mussel beds in the Proceedings of the Royal Society B, published today.

Albert Einstein theorized in 1905 that the movements of dust particles suspended in water was the result of collisions with water molecules. Research by Monique de Jager shows that the movements of individual mussels in mussel beds is similarly caused by collisions with conspecifics. Interactions with other mussels limit the freedom of movement of mussels and make mussels in dense mussel beds move in a similar fashion as molecules. These results emphasize the generality of Einstein’s theory and provide a new, different view on animal movement in their natural habitats.

“Many animals seem to move differently in dense environments than when they are alone,” says Monique de Jager, first author of the paper. “Mussels, for example, use a so-called ‘Lévy walk’, where long moves are alternated with small steps, mostly when they are alone. Mussels in dense mussel beds, however, behave totally different: they tumble around in the little space that they have left. This type of movement is very similar to ‘Brownian motion’ as found for instance in dissolved dust particles. Our research shows that this difference in movement pattern is not because mussels use a different movement strategy in different environments, but because of collisions with other mussels.”

“The mechanisms behind Brownian motion was a big scientific mystery in the 19th century,” says Johan van de Koppel, supervisor of Monique de Jager and honorary professor at the University of Groningen. “Why did the pollen particles that Robert Brown was trying to examine under the microscope shake so much? Einstein solved this puzzle in 1905 by showing that the pollen’s movements were caused by collisions with water molecules. Our research demonstrates that the Brownian movements of mussels are similarly the consequence of collisions, this time with other mussels.”

Also for other animals
The results of this study emphasize that ecologists have in the past ignored an important mechanism affecting the movement and dispersal of organisms. In most ecological studies, an observed movement pattern is believed to be an animal’s basic movement strategy.

The research led by Monique de Jager shows that interactions between organisms, such as collisions with conspecifics or interactions with predators, can be an important factor influencing the observed movement patterns. These interactions, rather than the intrinsic search and movement strategy of the organisms themselves, explain Brownian movement that we observe in many species.

Our mussel study therefore explains the change in movement that we observe when Tuna move from the open ocean to the continental shelf. It also clarifies why travelling to work is more time-consuming in New York or Tokyo than in a small village. Einstein’s theory on Brownian motion provides a universal explanation for all these phenomena.