Yeast Demonstrates Physics Can Lead to Multicellular Life without Mutations

What is Yeast?

Yeast is a single-celled fungus.

Frequent applications include:

• Baking (causes bread to rise).
• Production of alcohol (fermentation).
• Research in science (model organism).
• Reproduction through budding:
• A tiny bud develops on the mother cell.
• The nucleus splits, with one portion moving into the bud.
• The bud develops and separates, forming a new yeast cell.

What is Snowflake Yeast?

Typical yeast develops as individual cells; newly formed cells (buds) detach upon creation.

Snowflake yeast possesses a genetic alteration that stops buds from detaching.

Consequently, yeast cells adhere to each other, creating a formation similar to a snowflake.

These clusters expand quickly and become noticeable to the unaided eye in 12 hours.

Importance in Science: Snowflake yeast is utilized to examine the evolution of unicellular life into multicellular organisms.

Typically, multicellular organisms require specialized transport systems (such as blood vessels) to distribute nutrients.

However, snowflake yeast does not possess these biological systems, yet it continues to grow exponentially.

The Scientific Enigma

Based on current knowledge, growth ceases when inner cells can no longer receive nutrients.

Nonetheless, snowflake yeast in the laboratory kept expanding beyond anticipated boundaries.

Researchers aimed to comprehend how nutrients continued to reach every cell.

New Finding – Physical Mechanism Underlying Growth

The research revealed that a basic physical mechanism aids yeast growth: the movement of fluid.

Growth occurred solely in liquid (solution), not in jelly-like substances.

Fluid movement can be categorized into two types:

Diffusion: nutrients move from areas of high concentration to areas of low concentration.

Advection: the entire fluid flows, transporting nutrients along.

Diffusion by itself couldn’t account for extensive growth (only up to 50 micrometers).

Researchers detected advection — fluid entering the cluster from the sides and leaving from the top.

Snowflake yeast utilizes sugar (glucose) to generate alcohol and carbon dioxide.

This reduces the density of the surrounding fluid.

Fluids with lower density ascend, generating a natural upward movement (similar to rising hot air).

Evolutionary Importance

Multicellularity is traditionally believed to result from slow genetic mutations.

This study demonstrates that early multicellularity, prior to genetic alterations, could be permitted by physics and chemistry alone.

Multicellularity may eventually become a permanent characteristic of life due to genetic evolution.