Mice teeth explain the troubles with human wisdom teeth

Sep 26, 2007

During evolution, many of a species’ properties are shaped by ecological interactions. This is readily evident in mammalian teeth, whose many features closely reflect what each species eats. However, for a long time scientists have suspected that genetic and developmental interactions may also influence species-specific properties.

Now, researchers at the University of Helsinki’s Institute of Biotechnology show how development affects the evolution of teeth, and have devised a simple developmental model to predict aspects of teeth across many species. The results were published in Nature.

In the study in the field of evolutionary developmental biology, the researchers Kathryn Kavanagh, Jukka Jernvall and Alistair Evans in the Institute of Biotechnology of the University of Helsinki first studied cheek tooth, or molar, development in mice. Similarly to human teeth, mouse molars develop from front-to-back so that the first molar appears first and the posterior molars bud sequentially along the jaw. Normally the last molar to develop is the third, or wisdom tooth.

Experiments on cultured mouse molars revealed that the size and number of posterior molars depend on previously initiated molars. The mechanism, called an ‘inhibitory cascade’, acts much like a ratchet that cumulatively increases size differences of teeth along the jaw.

By quantifying their experiments, the researchers constructed a simple mathematical model which they then used to predict relative size and number of molars across many other mouse and rat species. They show that the model accurately predicts tooth proportions and numbers, one curious effect being that the second molar makes up one-third of total molar area, irrespective of species-specific molar proportions.

This new research demonstrates that with advances in the study of the molecular regulation of development, it is now possible to identify how development influences evolution. And this may help explain the troublesome wisdom teeth of modern humans - the blame may lie within a weak inhibitory cascade that allows the development of the last molar in a jaw that is too small.

Source: University of Helsinki

Explore further: Scientists target mess from Christmas tree needles

add to favorites email to friend print save as pdf

Related Stories

Woolly mammoth skeleton sold at UK auction

Nov 26, 2014

The skeleton of an Ice Age woolly mammoth fetched £189,000 ($300,000, 239.000 euros) at auction Wednesday as it went under the hammer in Britain with a host of other rare or extinct species.

New progress of the Neogene Suidae research

Oct 17, 2014

Dr. Hou Sukuan and Prof. Deng Tao from the Institute of Vertebrate Paleontology and Paleoanthropology(IVPP), Chinese Academy of Sciences reported a new species of Chleuastochoerus from the Linxia Basin, Gansu ...

Biology of early human relative uncovered

Jan 22, 2014

The partial skeleton of an ancient hominin has been uncovered for the first time in Tanzania, giving a new insight into the species' biology, say scientists.

Recommended for you

Scientists target mess from Christmas tree needles

8 hours ago

The presents are unwrapped. The children's shrieks of delight are just a memory. Now it's time for another Yuletide tradition: cleaning up the needles that are falling off your Christmas tree.

Top Japan lab dismisses ground-breaking stem cell study

16 hours ago

Japan's top research institute on Friday hammered the final nail in the coffin of what was once billed as a ground-breaking stem cell study, dismissing it as flawed and saying the work could have been fabricated.

Research sheds light on what causes cells to divide

Dec 24, 2014

When a rapidly-growing cell divides into two smaller cells, what triggers the split? Is it the size the growing cell eventually reaches? Or is the real trigger the time period over which the cell keeps growing ...

Locking mechanism found for 'scissors' that cut DNA

Dec 24, 2014

Researchers at Johns Hopkins have discovered what keeps an enzyme from becoming overzealous in its clipping of DNA. Since controlled clipping is required for the production of specialized immune system proteins, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.