Ancient Sponges may Represent Earth’s Earliest Animal Life,โฃ Newโ Research Suggests
Evidence suggests that ancient sponges may be among the first animals to have โคevolved on Earth, appearing substantially earlier than most otherโฃ multicellular organisms. A recent study, โfocusing on a specific organic compound,โ strengthens this hypothesis.
Researchers identified a geological stable sterol form, a 30-carbon (C30) sterol – a component of steroid groups including cholesterol – โฃwithin ancient rock formations. This sterol is typically found in the cell membranes โฃof complex organisms. The team connected โคthis specific sterol to Demosponges, a class of sea sponges, indicating the “chemical fossil” represents traces of early animal life.
“We did not know exactly what this organism โฃwas like atโฃ thatโ time,โฃ but theyโ must have lived in the ocean,โ soft body, and we suspectโ they did not have โฃa silica frame,” explained roger Summons, professor of geobiologyโข at MIT’s Department of Earth, Atmospheric and Planetary Sciences, as quoted by IFLโฃ Science.
Sponges, despite their โsimple appearance, are classified as animals. They are composed of diverse eukaryotic cells performing specialized functions,lack cell walls,and exhibit behaviors like eating,reproduction,and โresponding to their environment. However, they areโฃ relatively simple animals,โค lacking organs,โค tissues, and complex systems likeโ nervous systems or circulatory systems. Essentially, they are aggregations ofโ animal cells.
The emergence of these early โฃsponges predatesโฃ the Cambrianโ explosion, a period of rapid diversification of complex life forms marked by a sudden appearance of many animal groups โin the fossil record. Prior to this, life primarily consisted of โsimpler structures and โsingle-celledโ organisms.
Initialโค findings in 2009 suggested C30 sterols could indicateโฃ early animal life, but alternative theories proposed โthe sterols mightโฃ originate from other organisms or geological processes.
Thisโ new research bolsters the original claim.โ By analyzing drill cores and rock outcrops from Oman,western India,and Siberia,the team found evidenceโฃ linking the sterols strongly โขto Demosponges. โ
“You are not eukaryotes if you don’tโ have a comparable sterol or lipid membrane,” Summons stated.
further, the team synthesized C30 sterols inโฃ a laboratory setting, demonstrating their โproduction using enzymes encoded by Demosponge genes. This combined โevidence – analysis of theโข rock samples, characteristics of โฃmodern โsponges, and laboratory synthesis – โฃfirmly โsupportsโ the conclusion that the 635-million-year-old rocks contain evidence of ancient animal life.
“This isโฃ a combination of whatโ is in the โstone, what is in the sponge,โ and what you can make in theโฃ chemical laboratory. There are three lines of evidence that support and mutually reinforce each other, showing that this sponge is among the earliest animals on earth,” Summons concluded.
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