Multicellularity: How Do They Determine It Evolved 20+ Times?

[Patzee]

In a New Scientist article (also posted on many other sites):

"Lab yeast make evolutionary leap to multicellularity" (http://www.newscientist.com/article...ke-evolutionary-leap-to-multicellularity.html)...

there is the statement: "Multicellularity has evolved at least 20 times since life began, but the last time was about 200 million years ago, leaving few clues to the precise sequence of events."

How do they determine this? For example, by discovery of life forms that no longer exist in the fossil record or by some other method?

Thanks! Pat

 

[Borek]

Others will for sure give better answers, but no, it is not about fossils. Fossils don't carry enough information.

However, for example, you can compare biochemistry of two living organisms and the way cells exchange signals (they do, as they have to communicate for an organism to survive). All descendants of a first multicellular organism will share the communication engine biochemistry, if signals are different (that is, substances used to send signals are different), there is no common multicellular ancestor.

I am not sure that's exactly the way it was done, there are probably many different methods that will allow determination of whether two multicellular organisms are related, but this one should work at least in some cases.

 

[Patzee]

Borek, thanks! That's very helpful!