Wednesday, 17 May 2023

Creationism in Crisis - Researchers Observe Multicellularity Evolving in Only 3,000 Generations

Creationism in Crisis

Researchers Observe Multicellularity Evolving in Only 3,000 Generations

Macroscopic snowflake yeast with elongated cells fracture into modules, retaining the same underlying branched growth form of their microscopic ancestor.

A Journey to the Origins of Multicellular Life: Long-Term Experimental Evolution in the Lab | Research

Creationist frauds will often be seen recruiting new fools for their cult by feeding them disinformation about biology and what science, particularly, evolutionary biology supposedly can't explain.

The fact that bearing false witness, in this case against science, is forbidden in the Bible they purport to be defending and by the god they claim wrote it, betrays the fact that their objective if not to promote and defend the Christian religion but to recruit members for a money-making/political cult in order to manipulate and exploit them.

Some of the more infantile creationists may be trying to swell their ranks in the childish belief that the more people they can trick into believing their superstition, the more right it becomes. Those nagging self-doubts are such an existential threat to creationists that cognitive dissonance can give rise to absurd thinking.

One of the false claims you will often see being made is that biologists can't exolain how multicellularity evolved.

That claim can now be easily refuted by reference to an ongoing experiment in a aboratory in Georgia Tech, in which researchers have observed a single-celled yeast evolve into a multi-cellular organism in just 3,000 generations. The researchers have reported their findings in Nature.

In fact, this is only the latest in several lines of research about which creationists will have remained stoically ignorant:
Evolution of Multicellularity.

The evolution of multicellular organisms from single-celled ancestors is a complex and fascinating topic in evolutionary biology. While I can provide you with a brief overview of this process, it's important to note that my training data only goes up until September 2021, so I won't have access to the most recent scientific literature. Nonetheless, I'll do my best to provide you with a general understanding of this evolutionary transition.

The transition from single-celled to multicellular organisms is believed to have occurred multiple times throughout Earth's history. It is thought to have happened independently in various lineages, giving rise to the diverse array of multicellular life forms we observe today.

One hypothesis regarding the origin of multicellularity suggests that it evolved from simple, colonial groups of cells that gradually became more integrated and specialized over time. These colonial organisms, composed of genetically identical cells, may have gained certain advantages, such as increased size and the ability to perform more complex functions, by working together.

An important step in the evolution of multicellularity is the development of mechanisms for cell adhesion and communication. Cell adhesion molecules allow cells to stick together, forming tissues and organs. Intercellular communication systems, such as gap junctions or the release of chemical signals, enable coordinated actions among cells.

Once multicellularity was established, subsequent evolutionary processes led to increased complexity and specialization. Through mechanisms such as cell differentiation and division of labor, different cell types emerged within multicellular organisms. This specialization allowed cells to assume specific functions and work together for the overall benefit of the organism.

Research in this field has involved studying the evolutionary history of multicellularity through a combination of genetic, developmental, and comparative approaches. Comparative genomics, for instance, allows scientists to compare the genomes of different organisms and identify genetic changes associated with the transition to multicellularity.
A press release from Georgia Tech explains the research:
The world would look very different without multicellular organisms – take away the plants, animals, fungi, and seaweed, and Earth starts to look like a wetter, greener version of Mars. But precisely how multicellular organisms evolved from single-celled ancestors remains poorly understood. The transition happened hundreds of millions of years ago, and early multicellular species are largely lost to extinction.

To investigate how multicellular life evolves from scratch, researchers from the Georgia Institute of Technology decided to take evolution into their own hands. Led by William Ratcliff, associate professor in the School of Biological Sciences and director of the Interdisciplinary Graduate Program in Quantitative Biosciences, a team of researchers has initiated the first long-term evolution experiment aimed at evolving new kinds of multicellular organisms from single-celled ancestors in the lab.

Over 3,000 generations of laboratory evolution, the researchers watched as their model organism, “snowflake yeast,” began to adapt as multicellular individuals. In research published in Nature, the team shows how snowflake yeast evolved to be physically stronger and more than 20,000 times larger than their ancestor. This type of biophysical evolution is a pre-requisite for the kind of large multicellular life that can be seen with the naked eye. Their study is the first major report on the ongoing Multicellularity Long-Term Evolution Experiment (MuLTEE), which the team hopes to run for decades.

“Conceptually, what we want to understand is how simple groups of cells evolve into organisms, with specialization, coordinated growth, emergent multicellular behaviors, and life cycles – the stuff that differentiates a pile of pond scum from an organism that is capable of sustained evolution,” Ratcliff said. “Understanding that process is a major goal of our field.”

The Multicellularity Long-Term Evolution Experiment

Ozan Bozdag, a research scientist and former postdoctoral researcher in Ratcliff’s group and first author on the paper, initiated the MuLTEE in 2018, starting with single-celled snowflake yeast. Bozdag grew the yeast in shaking incubators and each day selected for both faster growth and larger group size.

The team selected on organism size because all multicellular lineages started out small and simple, and many evolved to be larger and more robust over time. The ability to grow large, tough bodies is thought to play a role in increasing complexity, as it requires new biophysical innovations. However, this hypothesis had never been directly tested in the lab.

Over about 3,000 generations of evolution, their yeast evolved to form groups that were more than 20,000 times larger than their ancestor. They went from being invisible to the naked eye to the size of fruit flies, containing over half a million cells. The individual snowflake yeast evolved novel material properties: while they started off weaker than gelatin, they evolved to be as strong and tough as wood.

New Biophysical Adaptations

In investigating how the snowflake yeast adapted to become larger, the researchers observed that the yeast cells themselves became elongated, reducing the density of cells packed into the group. This cell elongation slowed down the accumulation of cell-to-cell stress that would normally cause the clusters to fracture, allowing the groups to get larger. But this fact alone should have only resulted in small increases in size and multicellular toughness.

To uncover the precise biophysical mechanisms that allowed growth to macroscopic size, the researchers needed to look inside the yeast clusters to see how the cells interacted physically. Normal light microscopes were unable to penetrate the large, densely packed groups, so the researchers used a scanning electron microscope to image thousands of ultrathin slices of the yeast, which gave them their internal structure.

“We discovered that there was a totally new physical mechanism that allowed the groups to grow to this very, very large size,” Bozdag said. “The branches of the yeast had become entangled – the cluster cells evolved vine-like behavior, wrapping around each other and strengthening the entire structure.”

By simply selecting on organismal size, the researchers figured out how to leverage the biomechanical mechanism of entanglement, which ended up making the yeast about 10,000 times tougher as a material.

Snowflake yeast clusters go from ~100 cells per cluster (left tube) to nearly half a million cells per cluster (right tube).
“Entanglement has previously been studied in totally different systems, mostly in polymers,” said Peter Yunker, associate professor in the School of Physics and a co-author on the paper. “But here we’re seeing entanglement through an entirely different mechanism — the growth of cells rather than just through their movement.”

Observing the entanglement was a turning point in the researchers’ understanding of how simple multicellular groups evolve. As a brand-new multicellular organism, snowflake yeast lacks the sophisticated developmental mechanisms that characterize modern multicellular organisms. But after just 3,000 generations of laboratory evolution, the yeast figured out how to drive and co-opt cellular entanglement as a developmental mechanism.

Internal structure of the yeast. The researchers imaged thousands of ultrathin slices of the yeast using a scanning electron microscope.
Preliminary investigations of other multicellular fungi show that they also form highly entangled multicellular bodies, suggesting that entanglement is a widespread and important multicellular trait in this branch of multicellular life.

“I’m really excited to have a model system where we can evolve early multicellular life over thousands of generations, harnessing the awesome power of modern science,” Ratcliff said. “In principle, we can understand everything that is happening, from the evolutionary cell biology to the biophysical traits which are directly under selection.”

For a long time, humans have worked with biology to evolve new things – from the corn we eat to domesticated dogs, chickens, and show pigeons. According to Ratcliff, what their team is doing is not so different.

“By putting our finger on the scale of a single-celled organism’s evolution, we can figure out how they evolved into progressively more complex and integrated multicellular organisms, and can study that process along the way,” he said. “We hope that this is just the first chapter in a long story of multicellular discovery as we continue to evolve snowflake yeast in the MuLTEE.”
But you can guarantee that creationist frauds will still be trying to recruit scientifically illiterate fools into joining their cult by telling them that only magic done by a supernatural magician can explain how multicellularity arose, confident that their dupes will never fact check, provided what they are being told is what they want to hear so they can feel important enough.

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