© 1975-1979, 2008 Robert A. Freitas Jr. All Rights Reserved.

Robert A. Freitas Jr., Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization, First Edition, Xenology Research Institute, Sacramento, CA, 1979; http://www.xenology.info/Xeno.htm

Chapter 11.  Extraterrestrial Biomechanics

"...but why must they be of the same nature as ours? Nature seems to court variety in her Works, and may have made them widely different from ours either in their matter or manner of Growth, in their outward Shape, or in their inward Contexture; she may have made them such as neither our Understanding nor imagination can conceive."
          -- Christian Huygens, in The Celestial Worlds Discover’d; Or, Conjectures Concerning the Inhabitants, Plants and Productions of the Worlds in the Planets (1698)⁶⁰²

"I would even go so far as to say that, from the cosmic viewpoint, all terrestrial mammals are ‘humanoid.’ They all have four limbs, two eyes, two ears, one mouth, arranged symmetrically about a single axis. Could a visitor from Sirius really tell the difference between a man and, for example, a bear? (‘I’m terribly sorry, Mr. Prime Minister, but all humanoids look the same to me....’)"
          -- Arthur C. Clarke (1968)³⁷³

"Life elsewhere is likely to consist of odd combinations of familiar bits."
          -- Allen Broms, in Our Emerging Universe (1961)¹¹⁹¹

"Two large dark-coloured eyes were regarding me steadfastly. The mass that framed them, the head of the thing, it was rounded, and had, one might say, a face. There was a mouth under the eyes, the lipless brim of which quivered and panted, and dropped saliva. The whole creature heaved and pulsated convulsively. A lank tentacular appendage gripped the edge of the cylinder, another swayed in the air. Those who have never seen a living Martian can scarcely imagine the strange horror of its appearance...
          -- H. G. Wells, in The War of the Worlds (1898)

The rich diversity of multicellular life on our own planet should tip us off that nature will have produced similarly intricate designs elsewhere in our Galaxy. The flora and fauna of extrasolar worlds doubtless will differ markedly from terrestrial species. One has only to consider the tremendous variety of terran life to realize at once that we live in a grand planetary zoo without equal -- save that of another world. Nevertheless, there must exist some limits to strangeness, some basic, universal rules regarding the construction of physical beings.

Our imagination sorely needs stimulation rather than restraint. So perhaps it is appropriate to begin by attacking one of our most basic assumptions about alien life: That all organisms must be built of cells. Since phase separation is probably a fundamental prerequisite to life, and since small cells are virtually certain to arise prebiotically, it was not an unwarranted assumption, to be sure.

But it is not essential, either.

Interesting in this regard are the slime molds native to Sol III.⁴⁴⁴ At one stage in their life history, they are small and insignificant one-celled flagellates capable of individual multiplication by simple fission. At a later time, however, large clumps of these cells fuse together. The resulting single, large, amoeba-like organism is capable of collective movement as a single entity. During this "plasmodium" stage cell walls dissolve away, leaving an amorphous mass of living protoplasm which can grow as large as 25 centimeters or more.

Here’s the catch. Although there are many cell nuclei floating around inside, the "body" of the slime mold in the plasmodium stage bears no trace of the earlier division into many cells. The organism has, quite literally, metamorphosed into a large single-celled organism.*

Hence, large extraterrestrial beings plausibly may be unicellular.

Another peculiar possibility is the diffuse-organism concept. Despite the assertions by some that "no biological life has developed in which a single integrated organism has covered large geographic areas,"⁶⁰⁰ it has been pointed out by the renowned American entomologist Edward O. Wilson that a colony of social insects may be thought of as a kind of organism:

...weighing anywhere from less than one gram to as much as a kilogram and possessing from about a hundred to a million or more tiny mouths. It is an animal that forages amoeba-like over fixed territories a few meters in extent.... The giant of all such superorganisms is a colony of the African driver ant Dorylus wilverthi, which may contain as many as 22 million workers weighing a total of over twenty kilograms. Its columns regularly patrol an area between 40,000 and 50,000 square meters in extent.⁵⁶⁵

What would an ET with detachable cells be like? Would we recognize the parent organism as living? If it were intelligent, could it comprehend us? Contact with an alien diffuse-organism might prove frustratingly difficult for early human explorers of distant worlds.

[Note: See also the author's article "Extraterrestrial Zoology", published in 1981.]

* This idea has already been used in several science fiction stories by Larry Niven. His Bandersnatchi are an example of an elephant-sized extraterrestrial organism constructed on a unicellular basis. The creature consists entirely of "undifferentiated protoplasm."⁴⁵¹

Last updated on 6 December 2008