Ancient Molars: What Newly Discovered Fossils Have To Say

A recent study a 160,000-year-old archaic human molar fossil discovered in China offers the first morphological evidence of interbreeding between archaic humans and Homo sapiens in Asia. While this rare trait is primarily found in modern Asians and was thought to have evolved after H. sapiens dispersed from Africa, these findings point to a different evolutionary path.

The study appears in the journal Proceedings of the National Academy of Sciences. "The trait's presence in the fossil suggests both that it is older than previously understood and that some modern Asian groups obtained the trait through interbreeding with a sister group of Neanderthals, the Densiovans," says Shara Bailey, professor of anthropology at New York University. "In Asia, there have long been claims for continuity between archaic and modern humans because of some shared traits, but many of those traits are primitive or are not unique to Asians. However, the three-rooted lower molar trait is unique to Asian groups. Its presence in a 160,000-year-old archaic human in Asia strongly suggests the trait was transferred to H. sapiens in the region through interbreeding with archaic humans in Asia."

The First Adult Molars

McMaster University researchers discovered that a person's first permanent molars carry a life-long record of health information dating back to the womb. In fact, they store vital information that can connect maternal health to a child's health hundreds of years later. Dentin, the material under the enamel that makes up the bulk of a tooth, forms in microscopic layers that compare to the rings of a tree. Adequate formation of those layers is dependent on vitamin D. Dark streaks develop in periods when the body is deprived of the critical nutrient, usually because of a lack of sunlight.

The researchers examined modern and archaeological tooth samples, including teeth taken from two skeletons from 19th century Quebec. The toddler's undescended molar showed that her mother had suffered a vitamin D deficiency during pregnancy, a possible clue to the child's early death. The young man's molar also showed his mother had suffered vitamin D deficiency, raising the possibility of a connection between his mother's health and his early death. In that time social practices and weather conditions meant that pregnant women in particular would have had very little exposure to the sun, before it became clear how necessary sunlight or substitute sources of vitamin D are to good health.

Combined with other data, patterns in dentin can create rich banks of knowledge about past conditions, including the health impacts of living in low-light environments. These valuable records begin during the original formation of teeth in the fetal stage and reflect the health of the mother during pregnancy. All of the body's primary or "baby" teeth, which start forming in utero, are lost in childhood. The first permanent molars emerge around age six and also start forming in utero and stay in the mouth throughout one's adult life, where they retain a record of vitamin D intake dating back to the mother's pregnancy.

This record provides a critical intergenerational link that can offer valuable clues connecting maternal health to the eventual fate of a child. "It's a living fossil of your life, starting in utero," says anthropologist Megan Brickley. "Conceivably, it would be possible to remove the molar of anyone and compare their health to the evidence in the tooth. We've been able to set out really clear evidence that there is part of the first permanent molar that records what happened in the life of the mother. This is a tool that people can use. It can be used in current health research, and in bio-archaeological research."

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With over 30 years of writing and editing experience for newspapers, magazines and corporate communications, Kevin Kerfoot writes about natural health, nutrition, skincare and oral hygiene for Trusted Health Products’ natural health blog and newsletters.

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Founder Ray Spotts has a passion for all things natural and has made a life study of nature as it relates to health and well-being. Ray became a forerunner bringing products to market that are extraordinarily effective and free from potentially harmful chemicals and additives. For this reason Ray formed Trusted Health Products, a company you can trust for clean, effective, and healthy products. Ray is an organic gardener, likes fishing, hiking, and teaching and mentoring people to start new businesses. You can get his book for free, “How To Succeed In Business Based On God’s Word,” at www.rayspotts.com.