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Tanya M. Smith: A Bite Through Time

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California Academy of Sciences

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Dental Discoveries: Teeth Contain Growth Rings Like Trees

04 min 07 sec

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Tanya Smith, Professor of Human Evolutionary Biology at Harvard University, explains how our teeth grow rings similar to trees and how they also create physiological markers that record our lives.
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55 min 02 sec

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Encyclopædia Britannica Articles

human evolution: Evolution of modern human beings from extinct nonhuman and humanlike forms. Genetic evidence points to an evolutionary divergence between the lineages of humans and the great apes on the African continent 8–5 million years ago (mya). The earliest fossils considered to be remains of hominins (members of the human lineage) date to at least 4 mya in Africa; they include the genus Australopithecus and other forms. The next major evolutionary stage, Homo habilis, inhabited sub-Saharan Africa about 2–1.5 mya. Homo habilis appears to have been supplanted by a taller and more humanlike species, Homo erectus, which lived from c. 1,700,000 to 200,000 years ago, gradually migrating into Asia and parts of Europe. Between c. 600,000 and 200,000 years ago, Homo heidelbergensis, sometimes called archaic Homo sapiens, lived in Africa, Europe, and perhaps parts of Asia. Having features resembling those of both H. erectus and modern humans, H. heidelbergensis may have been an ancestor of modern humans and also of the Neanderthals (H. neanderthalensis), who inhabited Europe and western Asia from c. 200,000 to 28,000 years ago. Fully modern humans (H. sapiens) seem to have emerged in Africa only c. 150,000 years ago, perhaps having descended directly from H. erectus or from an intermediate species such as H. heidelbergensis.; human evolution on britannica.com
tooth: Cross section of an adult molar. The crown (the part of the tooth above the gum) is protected by a …© Merriam-Webster Inc.Any of the hard structures in the mouth used for biting and chewing and in speech. Each consists of a crown above the gum and one or more roots below it, embedded in the jaw. Its inner pulp contains the blood and nerve supply for the bonelike dentin, covered in the crown by enamel, the hardest tissue in the body. Twenty primary (baby) teeth come in by age 2 1/2 and fall out between ages 5 and 13 to be replaced by 32 permanent teeth. The incisors, in front, are shaped mostly for biting, the pointed canines for tearing, and the premolars and molars for grinding food. The teeth are subject to caries (decay), caused by acid from bacteria in plaque, a yellowish film that builds up on teeth. Misalignment of teeth between the upper and lower jaws can grind down the teeth and cause problems in chewing. Elsewhere, it is a cosmetic problem. Both can be treated with braces. See also dentistry.; tooth on britannica.com

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Weegiewarbler

Posted: 02.02.12, 07:12 PM

I would have loved to have watched this lecture for a second time, as the subject is fascinating. However, the speaker's use of the word "Right?" as punctuation at the end of EVERY sentence is incredibly distracting and thoroughly irritating. Surely, someone of this educational level is capable of expressing herself better?

deeliciousplum

Posted: 04.18.11, 10:18 AM

I love how Tanya uses her sense of humour to make the topic of evolutionary anthropology fun for those, like myself, who may not have a thorough enough biology background for what she is sharing in. Valuable and interesting talk on teeth and of their markers of time. Thank you for sharing this talk.