From unicellular to multicellular reproduction. paradox?

[moe darklight]

I'm having a little trouble picturing how this would happen and I can't find any information on this.
I understand that the jump from a unicellular organism to a multicellular matrix can happen, but I'm having trouble picturing how a matrix of genetically identical cells can evolve into a breeding organism with organ systems, etc.

here's my problem:
- for that first multicellular organism (which would look more like a membrane of cells than an animal) to reproduce and evolve, wouldn't it need a mate/reproductive system? but in order to have a mate, the organism would have had to reproduce in the first place (that is, there would have to be more than one of these), which is impossible without having a mate...

I'm guessing there is a flaw in my logic, any website/book/video that describes this in detail would be helpful.

 

[gerben]

You should just think of some more intermediate stages, that will make it seem less problematic.

The first stage could be something like a ball of cells that stick together. Now and then some cells split off and form balls of cells themselves. Later on different cells within the ball get different functions based on their relative position within the ball. Some part may get the function to produce cells that leave the ball to form new balls. This would still be an asexual stage. Again later there may be two kinds of cells that leave the ball both with only halve the genetic material that is needed to function, and thus two of those need to combine to from a complete cell. These cells would be reproductive cells (gametes), at this stage they are not very specialized yet and any two can combine, no matter whether they came from the same ball or from different ones. Later on you might get too different “shapes” of gametes and only two complementary ones can combine. Every ball could be producing both of them tough, i.e. it could be a hermafrodite. Later on again, you could get balls that only produce one kind of these productive cells. There might be a period where you have all three possibilities, hermafrodites, males and females. They would just all throw out gametes into the sea for them to find and combine with complementary ones.

 

[ravenprp]

The evolution from unicellular to multicellular reproduction is indeed a paradox that has puzzled scientists for a long time. It is difficult to imagine how a group of genetically identical cells could evolve into a complex organism with specialized organ systems and the ability to reproduce sexually.

One way to understand this paradox is to look at the different stages of evolution that could have led to multicellularity. The first step would be the formation of a colony of cells, where individual cells come together and function as a unit. This could have been driven by environmental pressures, such as the need for protection or access to nutrients.

Once the colony is established, it could have evolved into a true multicellular organism through a process called cellular differentiation. This is when different cells within the colony start to specialize and take on different roles, such as reproductive cells, digestive cells, or muscle cells. This specialization allows the organism to become more complex and function more efficiently.

As for the issue of reproduction, it is believed that the first multicellular organisms were able to reproduce asexually through cellular division. This means that the colony would simply divide into two or more daughter colonies, each with the same genetic makeup as the parent colony. Over time, as the organism evolved and developed more complex organ systems, sexual reproduction could have emerged as a more efficient way to diversify and adapt to changing environments.

In summary, the evolution from unicellular to multicellular reproduction is a complex and ongoing process that involves various stages and mechanisms. While there may be some gaps in our understanding, ongoing research and discoveries are shedding more light on this fascinating paradox. I recommend exploring resources such as scientific journals and books on evolutionary biology for more detailed explanations and evidence.