How Genes Have Harnessed Physics to Grow Living Things

"Sip a glass of wine, and you will notice liquid continuously weeping down the wetted side of the glass. In 1855, James Thomson, brother of Lord Kelvin, explained in the Philosophical Magazine that these wine "tears" or "legs" result from the difference in surface tension between alcohol and water. "This fact affords an explanation of several very curious motions," Thomson wrote. Little did he realize that the same effect, later named the Marangoni effect, might also shape how embryos develop."

"The finding is part of a trend that defies the norm in biology. Typically, biologists try to characterize growth, development, and other biological processes as the result of chemical cues triggered by genetic instructions. But that picture has often seemed incomplete. Researchers now increasingly appreciate the role of mechanical forces in biology: forces that push and pull tissues in response to their material properties, steering growth and development in ways that genes cannot."

"Modern imaging and measurement techniques have opened scientists' eyes to these forces by flooding the field with data that invites mechanical interpretations. "What has changed over the past decades is really the possibility to watch what happens live, and to see the mechanics in terms of cell movement, cell rearrangement, tissue growth," said Pierre-François Lenne of Aix Marseille University, one of the researchers behind the recent study."

The Marangoni effect, caused by surface-tension differences, drives fluid motions such as wine tears and can also shape embryonic development. In embryonic tissues, Marangoni-driven flows can cause a homogeneous cell mass to elongate and establish a head–tail axis. Mechanical forces operate alongside genetic and chemical cues, pushing and pulling tissues according to material properties and steering growth in ways genes alone cannot dictate. Modern imaging and measurement techniques enable live observation of cell movement, rearrangement, and tissue growth, making mechanical interpretations increasingly visible. Interest in pre-genetic models of form and mechanics, such as those proposed by D'Arcy Thompson, has been revived.

Read at WIRED