Dental crowns reveal the diet of a species

The smiles of Tom and Jerry have something in common after all

According to recent research, the complexity of tooth surfaces reveals the diet of a species. Scientists at the University of Helsinkiís Institute of Biotechnology and Department of Geology showed that the more complex the surface of an animal's teeth, the greater the share of vegetables in its diet. For instance, the teeth of carnivores and rodents differ in almost every aspect, but if a carnivore and a rodent eat similar food, their teeth are equally complex. The results were published in Nature.

The size, number, occlusion and dental crown cusps of carnivores and rodents, such as cats and mice, are very different. Based on their research, the Helsinki scientists discovered that although the teeth of rodents and predators seem very different, the values describing their complexity correspond if the species share a similar diet. Both groups have species that eat both meat and vegetable foods.

The scientists studied the differences in the teeth of various species by measuring the molar crowns of 81 mammalian species and, based on the measurements, creating 3D virtual models of them. The models were then used to develop new methods of measurement, which enable scientists to identify all the parts of teeth that break down the food, the 'tools', as it were.

New database is the first to offer information on phenotypes

The 3D virtual models were entered in the MorphoBrowser database created by the team's scientists. The database now contains data on fossils, existing animals as well as the modified teeth of mutant mice. The open access database for the first time makes phenotypes, or 3D models of the information contained in the genes, publicly available on the Internet. This can be compared to the information on the genetic sequences of different species (such as the human genome), which have been available on public databases for quite a while.

3D measurements enable scientists to determine the diet of extinct animals even in taxonomic groups that have no counterparts in living species. Indeed, the database is particularly useful to evolutionary scientists, who study the diet of extinct species based on the shape of their molars. This new approach also creates opportunities for studying the relationship between dental shapes and developmental biology.

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The research was financed by the Systems Biology and Bioinformatics Research Programme of the Academy of Finland.

Related Internet databases maintained by University of Helsinki scientists:
The MorphoBrowser database: http://pantodon.science.helsinki.fi/morphobrowser/
Database of fossil mammals: http://www.helsinki.fi/science/now/
Gene expression in tooth: http://bite-it.helsinki.fi/

For more information please contact:

Professor Mikael Fortelius, Department of Geology
Tel. +358 50 533 7267, fax +358 9 19150826, mikael.fortelius@helsinki.fi

Alistair Evans, Researcher, Institute of Biotechnology
Tel. +358 405 066558 , fax. +358 9 19159366, arevans@fastmail.fm

Jukka Jernvall, Professor of Evolutionary and Developmental Biology, Institute of Biotechnology
Tel. +358 40 7403478 , fax. +358 9 19159366, jernvall@fastmail.fm

Publication: Evans, A. R., Wilson, G. P., Fortelius, M. & Jernvall, J. High-level similarity of dentitions in carnivorans and rodents. Nature 13.12.2006.


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