Evolution of multicellular yeast observed in the lab?
Published: 19 May 2013 (GMT+10)
Kori S. from the United States writes:
I would like to start off by thanking the men and women at CMI for their hard work in defending the biblical account of creation. I have long been a reader of your articles and have used the information presented to bolster my faith and the faith of others.
Recently however, a friend told me that Evolution had been observed inside a laboratory and pointed me towards this [Weblink removed as per feedback rules—Ed.]
It basically tells us that single cellular organisms were observed evolving into multicellular organisms. The organisms in question were the baker’s yeast (Saccharomyces cerevisiae). I spent a bit searching the site but was unable to come across any useful information. I would appreciate any help or information you have in this matter.
CMI’s Shaun Doyle responds:
Thank you for your email and your encouraging words. We are always glad to be of help.
We covered this briefly in a short focus article in ‘Multicellular yeast evolving in the lab?’, Creation 34(1):9, 2012. However, I think it will be helpful to take the time to expound on the issue more fully. The key to understanding how this fits with Scripture and does not prove microbes-to-man evolution is this quote from the research article:
“Multicelled snowflake-phenotype yeast evolved in all 15 replicate populations, in two separate experiments, within 60 d[ays] of settling selection [emphases added].”1
That this multicellular condition ‘evolved’ in all the experiments so quickly suggests that it’s neither a random occurrence nor something completely new. The yeast almost certainly already had the genetic programming to enable clumping under certain environmental conditions. This is not the evolution of something completely new, but the activation of latent information that enables the yeast to survive in certain environments.
Another point is that evolutionists think yeast evolved (or devolved) from multicellular ancestors because they are fungi. The problem is these experiments would be far easier to explain by saying the yeast retained the capacity for multicellular growth in its ancestors rather than evolving it afresh all over again.2 However, this would not involve any addition of new genetic information (specified complexity), and as such provides no support for microbes-to-man evolution.
Finally, this sort of ‘multicellularity’ is nothing like what we find among plants and animals. It possesses genetic sameness, intercellular cohesion, and programmed cell death (see Apoptosis: cell ‘death’ reveals Creation and The non-evolution of apoptosis). While these are all necessary for multicellularity, but they are not sufficient for the complex multicellularity found in plants and animals. All these traits can exist in creatures that can survive and reproduce as single-celled organisms. On top of this, multicellularity in plants and animals needs a way to produce and maintain distinct cell types within the organism. This is not what the research demonstrated the evolution of:
“Although known transitions to complex multicellularity, with clearly differentiated cell types, occurred over millions of years, we have shown that the first crucial steps in the transition from unicellularity to multicellularity can evolve remarkably quickly under appropriate selective conditions [emphasis added].”
This is a misleading statement because it suggests that the yeast clumps resemble the first steps on a journey to complex multicellularity. But note the highlighted section. The problem is that those “clearly differentiated cell types” require top-down cell differentiation programs to produce and maintain such a structure, not just ‘cooperation’ between different cells (see Evolution of multicellularity: what is required? and Earliest multicellular life?). Consider this statement:
“The un-coupling of immortality and totipotency proved not possible in V. carteri: these traits are express [sic] either together and fully (i.e. in the gonidia) or not at all (i.e. in the somatic cells). Immortality and totipotency are thus still tightly linked in V. carteri, as they are in their unicellular ancestors. In support of this view is the fact that ‘cancer-like’ mutant somatic cells, in which immortality but not totipotency is re-gained, are missing in V. carteri. There are, however mutant forms of V. carteri … in which somatic cells re-gain both immortality and totipotency, but in neither of these mutants are the two traits expressed partially or differentially (e.g. limited mitotic capacity or multipotency).”3
This is a really important statement for understanding why evolving complex multicellularity from basic multicellularity is practically impossible, so I’ll spell it out a bit. First, V. carteri is a type of algae (volvocine algae) that possesses the most advanced form of basic multicellularity we know of. It forms a simple and absolute divide between the somatic (non-reproductive) cells and the germ (reproductive) cells. Each germ cell can divide indefinitely (immortality) and they can reconstruct the whole organism (totipotency). The somatic cells can’t do either—once established they no longer divide at all. This means the multicellular state of volvocine algae can only last for a few days at most. Without the ability to replenish the somatic cells, the whole shell of somatic cells soon falls apart (this is an important part of the life cycle of these algae).
This also produces very different conditions from plants and animals when the development process goes awry. Developmental mutations in volvocine algae can produce somatic cells that behave exactly like germ cells—they regain both totipotency and immortality. In effect, the somatic cells become new organisms in themselves. However, volvocine algae can’t produce cancer-like growths. Why? Cancer is essentially a growth of cells that has regained immortality but not totipotency. This however presupposes that these two traits can be decoupled from each other in the organism. They can’t be so divided in volvocine algae. On the other hand, when development and maintenance in plants and animals goes awry, it can produce cancer. This illustrates the hallmark of a cell differentiation program—ability to decouple totipotency and immortality. It produces such things as stem cells for specific tissues (they can produce a wide range of different cell types, but not all cell types), and cells that are programmed to stop dividing and/or die out after a certain number of cell divisions (e.g. serial cell differentiation).
What we have is a fundamental difference between these different types of multicellularity. The yeast clumps are of the same type as the algae above—basic and without cell differentiation programs. Plants and animals on the other hand have body plan programs that involve the creation and maintenance of numerous different cell types. This is imposing a new level of organization ‘from above’, and is not something that can be explained in terms of its parts. (For an explanation of the concept, please see Life’s irreducible structure—Part 1: autopoiesis)
The whole point is that these yeast clumps do not show that animals evolved from amoebas. They are still yeast. What these experiments demonstrate is the amazing ability of organisms to adapt to different circumstances while retaining their unique biological identity (see How life works). Life was designed to adapt to extreme changes, but never to change from one kind into another in that process.
Creation Ministries International
- Ratcliff, W.C., Denison, R.F., Borrello, M. and Travisano, M., Experimental evolution of multicellularity, PNAS 109(5):1595–1600, 2012; p. 1599. Return to text.
- Holmes, B., Lab yeast make evolutionary leap to multicellularity, New Scientist 210(2818):10–11, 23 June 2011, www.newscientist.com. Return to text.
- Michod, R.E., Nedelcu, A.M. and Roze, D., Cooperation and conflict in the evolution of individuality IV. Conflict mediation and evolvability in Volvox carteri, BioSystems 69:95–114, 2003; p. 105. Return to text.