Two recent articles in the online science journal, TheScientist, intrigue me with the apparent sociality of cells.
One article reports Philip Donaghue’s discovery of apparently multicellular fossils, similar to jellyfish, from over 2 billion years ago, 200 million years earlier than we thought multicellularity first began.
The fossils show only the outsides of jellyfish-like creatures, with hints of cell-to-cell communication mechanisms. One problem is that some of the same mechanisms are used by groups of single-celled organisms. So with no innards to go on, it’s hard to be sure these fossils qualify as multicellular.
Yet multicellularity has evolved many times, an indication that it is often a successful survival strategy. It allows an organism to be larger, with nutrients and information passing to inner cells from outer cells. Large size may keep an organism (and hence, its cells) from being eaten. Or large size may increase the possible size and quantity of prey, a boon to all the cells involved. Or it may make metabolism more efficient, providing the multicellular organism with time to move beyond mere food consumption to courting or nesting. Or any number of other advantages.
The second article reports Milica Radisic’s biomedical engineering of heart cells from stem cells. She places the stem cells on a scaffolding of cardiac tissue and supplies them with nutrients and oxygen: Not only do these cells begin to “beat,” but they find each other, connect with one another, and form a beating tissue like the natural tissue of hearts. And they do this in response to a series of electrical impulses that simulate the electric impulses that pass through natural hearts from their controlling nodes.
So what gives here? Two very different types of cells, some direct descendants of single-celled organisms, some stem cells that just become cardiac cells by finding themselves on a support structure of heart cells, all connect with each other and function cooperatively.
Yet another wonder in a universe of wonders, don’t you think?