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The Role of Sponges in the Galaxy

There are many questions of key interest to SETI (the Search forExtraterrestrial Intelligence). For example: Why didn?t the dinosaurs go to themoon? They had 200 million years and many species had hands with an opposabledigit, big brains, and were bipedal.

Another entirely different SETI question could be: What do MedievalArabic texts have to say about the origin of optics? Light was thought to comefrom the eye at the beginning of the Middle Ages but within a few centuriesadvanced optical studies emerged from Arab countries with refracting lenses,prisms, and light was understood clearly to go into, not out of, the eye. Suchan emergent process would be essential to understand if one wants to generalizethe development of telescopesby intelligent civilizations.

Another interesting SETI-related question: When consideringthe communication systems of more advancedtechnical civilizations, what can we expect their communication system tobe like? Since something like 98% of the stars in the solar neighborhood areapparently older than the Sun (and other reasons) we can likely expect that anextraterrestrial technology will be significantly more advanced than ours. Asan example, one can hardly ignore recent developments in quantum teleportationas a possible neat trick for instantaneously getting large amounts of informationacross the galaxy. (It may or may not be possible to then read thatinformation faster than light, but that?s another story).

These are all interesting SETI questions and might make goodarticles themselves. But for today?s essay let?s ask ourselves thisSETI-related question: Would the development of our technical civilization havebeen possible without sponges? (We shall not so much answer this question inour essay as explain why we asked it.)

Given that a tool-wielding species has to start somewhere,humans apparently started at least 4 million years ago chipping rocks to formcutting surfaces. We see wild chimpanzees also doing this today; they alsotrain their offspring to do this as well so it is a learned, or cultural,behavior. But as it turns out, banging special kinds of rocks together canproduce an additional feature of technology, one that would come to distinguishus as a species about 2 million years ago. It all started when we bangedtogether iron pyrite with ocean sponges - actually, to state it more properly,we started to bang together iron pyrite with a metamorphosed mixture of chalkwith the internal skeletons of ocean sponges. This metamorphic chalk and spongeskeletal material is commonly known as ?flint.? And, as we know, when struckwith iron, it makes a spark of fire. And we are the only species that usesfire. (I?m not counting an entertaining raven that actually does a nightclubtrick in Las Vegas that includes striking a match to light a cigar.)?

So, although flint is an inorganic mineral, almost all thesilicate in it is derived from the dissolved skeletons of sponges. Thisstrike-sparking is considered the earliest form of fire making. Later steelwould be substituted for the iron pyrite, but flint was used for millenniabefore the invention of matches in the 19th century. And it would be difficultto argue for a more important invention to the survivalof the human species than the making of fire - especially during thefrequent ice ages that accompanied early northward migrations out of Africa. Itcould also be argued that fire making was the first big step of our speciestoward a technical civilization.

It turns out, then, that the process of sponge skeletonsdissolving in pre-lithified chalk ooze - dehydrated and hardened intomicroscopic quartz crystals forming flint - was essential (along with trees,but that?s another story) to the survival and eventual technical success of ourspecies on this planet. It could be argued that without sponges humans wouldnot be listening to and transmitting messages over interstellar distancestoday. So, lookingfor extraterrestrial technology? Then it might be a good idea to know wherein the galaxy the sponges are. The humble sponge, or something like it, may beessential for any species to first come up with the making of fire. And on ourplanet, if you don?t have a dishwasher, they still come in pretty handy too.


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Laurance R. Doyle

Laurance Doyle is a principal investigator for the Center for the Study of Life in the Universe at the SETI Institute, where he has been since 1987, and is a member of the NASA Kepler Mission Science Team. Doyle’s research has focused on the formation and detection of extrasolar planets. He has also theorized how patterns in animal communication, like those of social cetaceans, relate to humans.