At the New York Times, Carl Zimmer asks, Can Answers to Evolution Be Found in Slime? (October 3, 2011). The short answer is yes, certainly, but if you really must insist that all the answers be Darwinian, well then no, not really. Of course not. Here’s Zimmer on how slime molds (colonies of amoebas) can act like a multi-celled animal:
Today, biologists no longer think of Dictyostelium as an embryo: It is more like a society of amoebas that come together for a common cause, for which some will sacrifice themselves.
The organisms respond to starvation by rushing together by the thousands into a single blob. The blob stretches out into a slug-shaped mass about one millimeter long (one twenty-fifth of an inch), which then crawls like a worm toward light.
You could actually see it. It’s somewhat like this: –
Once it reaches the surface of the soil, the slug undergoes another transformation: Some of the cells turn into a stiff stalk, while the others crawl to the top and form a sticky ball of spores. They stick to the foot of an animal and travel to a hospitable place.
Inside the slug, about 1 percent of the amoebas turn into police. They crawl through the slug in search of infectious bacteria. When the amoebas find a pathogen, they devour it. These sentinels then drop away from the slug, taking the pathogen with it. They then die of the infection, while the slug remains healthy.
More amazing stuff. What it all demonstrates is that life forms need not become official multicellular animals in order to achieve some of the benefits – provided, of course, that they aim no higher than, say, the slug. (It could get testy if they needed a Parliament … )