Our sensitive teeth trace back to an extinct “body armor” fish that existed 465 million years ago, according to scientists.
A recent study reveals how sensory tissue found in the exoskeleton of ancient fish connects to the same “genetic toolkit” responsible for the development of human teeth.
Study co-authors from the University of Chicago, including Yara Haridi, state, “This shows that ‘tooth’ is also sensory even when it is inside the mouth,” as noted in a recent statement. Their findings were published in the journal Nature on Wednesday (May 21).
Initially, researchers discovered early vertebrates in the fossil record and sought fossil specimens from the Cambrian and Ordovician periods (541 to 443 million years ago). One indicator of vertebrate species is the existence of internal tubules in dentin—this calcified tissue resides just below human tooth enamel but is observable in the external structure of ancient fish armor.
By employing high-resolution CT scans of the jawless fish species Anatolepis heintzi, researchers uncovered what seemed to be pores filled with dentin. To validate this, they compared A. heintzi to a collaborative grouping of ancient fossils alongside modern marine species.
Upon closer examination, they recognized that the supposed dentin-lined pores resembled sensory organs found in crab shells, which indicated that A. heintzi was part of ancient invertebrate arthropods rather than vertebrates.
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Clarifying the classification of A. heintzi has yielded significant new insights: Both ancient vertebrates like fish and ancient arthropods developed similar mineralized tissues to help them sense their surroundings. This mineralized tissue eventually evolved into dentin and sensitive teeth.
Recent research supports the notion that sensory structures first emerged within exoskeletons at least 460 million years ago, and throughout evolutionary history, animals have utilized the same “genetic kits” to form teeth.
The researchers noted in this study, “When viewed through this evolutionary lens, the sensitivity of teeth in the mouth is not a mystery, but rather an example of evolutionary origins stemming from the sensory armor of early vertebrates.”
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Source: www.livescience.com