New project may give insights into the evolution of human teeth

NERC has agreed to fund a project worth nearly £680k to investigate how teeth evolved in our earliest ancestors.

The three-year project could give researchers a new insight into the evolution and development of teeth and their arrangement in the mouth - called dentition. It may also reveal why humans and mammals only develop one or two sets of teeth in their lifetime, compared to their ancestors, the bony fish, which constantly regenerate their teeth.

Every jawed vertebrate needs teeth to function and feed. But exactly how teeth evolved is poorly understood, because it is difficult to interpret different stages of tooth development from fossils.

“We still don’t have a clear understanding of how dentitions are built,” explained Professor Moya Meredith Smith of King’s College London, a principal researcher of the study. “To understand dentition patterns you need to look at animals that build their teeth on a regular basis, like fish.”

The team, co-ordinated by Dr Zerina Johanson of the Natural History Museum, plan to look at the development of different teeth arrangements in modern day vertebrates and then apply their findings to fossils from the same group.

Jawed vertebrates evolved into several different types of animal and fish, but there are only two major groups, which are still living today. One is sharks, or Chondrichthyes; while the other is Osteichthyes, or bony fish.

“Bony fish eventually evolved into mammals, like humans. But to define how the teeth evolved we don’t want to look at dentitions in mammals like mice. Instead, if you want to define how dentition evolved you need to look at more primitive members of groups,” explained Dr Zerina Johanson.

The grant will look at modern day Chondrichthyans, such as sharks and rays, to give them an insight into how the teeth from both these groups evolved.

While a lot is known about the dentition of modern day Osteichthyans, like tuna, salmon or seahorses, little is known about their early ancestors.

Professor Smith, Dr Johanson and their colleagues hope to change this when they compare their findings about Chondrichthyans to fossil specimens of early Osteichthyans. They hope to discover whether the two groups share a common dentition or whether the teeth in the cartilaginous sharks and rays evolved very differently to the boned fish.

The third principle investigator on the grant is Dr Gareth Fraser of the University of Sheffield. He will look at the genetics behind different types of dentition.

He said, “Osteichthyan dentitions have been intensely studied in recent years, and we even understand what genes are involved in producing these dentitions. Despite this, even within this group we know nothing about tooth development of more primitive Osteichthyans, such as the paddlefish and gar. As well, and perhaps somewhat surprisingly, we know very little about how genes control development of shark and ray dentitions.”

Dr Fraser also explained that, while teeth are not easily regenerated in the lab, the team are looking closely at natural tooth regeneration in fishes to see how they regenerate teeth and how it can be maintained in something like a shark, where there is continuous replacement.

“You can’t regenerate teeth but people are now starting to look more seriously at how certain fish regenerate teeth and some bony fish continually regenerate (although sharks do it more regularly),” said Dr Johanson. “If we can understand what cells and genes are involved in regeneration of shark teeth then maybe we can look at teeth in humans and see comparable genes that can be used to regenerate teeth. But that is still very much in the distant future.”

Notes

1. There are five principle investigators on the project in total, who each contribute a specialist understanding of the difference research fields necessary for the project. These include a specialist in dentistry - Professor Timothy Watson of King’s College London - and a shark and ray expert - Dr Charles Underwood, of Birkbeck College.

2. NERC is the largest funder of environmental science in the UK. We invest £330m in cutting-edge research, training and knowledge transfer in the environmental sciences. Our scientists study and monitor the whole planet, from pole to pole, and from the deep Earth and oceans to the edge of space. We address and respond to critical issues such as environmental hazards, resource security and environmental change. Through collaboration with other science disciplines, with UK business and with policy-makers, we make sure our knowledge and skills support sustainable economic growth and public wellbeing - reducing risks to health, infrastructure, supply chains and our changing environment.

3. Winner of Best of the Best in the Museums + Heritage Awards 2013, the Natural History Museum welcomes five million visitors a year. It is also a world-leading science research centre. Through its collections and scientific expertise it is helping to understand and maintain the diversity of the planet, with groundbreaking partnerships in more than 70 countries.

4. King’s College London is one of the top 20 universities in the world (2013-14 QS World University Rankings), and the fourth oldest in England. A research-led university based in the heart of London, King’s has more than 25,000 students (of whom more than 10,000 are graduate students) from nearly 140 countries, and some 6,500 employees. King’s is in the second phase of a £1 billion redevelopment programme which is transforming its estate. King’s has an outstanding reputation for providing world-class teaching and cutting-edge research. In the 2008 Research Assessment Exercise for British universities, 23 departments were ranked in the top quartile of British universities; over half of our academic staff work in departments that are in the top 10 per cent in the UK in their field and can thus be classed as world leading. The College is in the top seven UK universities for research earnings and has an overall annual income of nearly £450m. King’s has a particularly distinguished reputation in the humanities, law, the sciences (including a wide range of health areas such as psychiatry, medicine, nursing and dentistry) and social sciences including international affairs. It has played a major role in many of the advances that have shaped modern life, such as the discovery of the structure of DNA and research that led to the development of radio, television, mobile phones and radar. It is the largest centre for the education of healthcare professionals in Europe; no university has more Medical Research Council Centres. King’s College London and Guy’s and St Thomas’, King’s College Hospital and South London and Maudsley NHS Foundation Trusts are part of King’s Health Partners. King’s Health Partners Academic Health Sciences Centre (AHSC) is a pioneering global collaboration between one of the world’s leading research-led universities and three of London’s most successful NHS Foundation Trusts, including leading teaching hospitals and comprehensive mental health services.

5. With nearly 25,000 of the brightest students from 117 countries coming to learn alongside 1,209 of the world’s best academics, it is clear why the University of Sheffield is one of the UK’s leading universities. Staff and students at Sheffield are committed to helping discover and understand the causes of things - and propose solutions that have the power to transform the world we live in. A member of the Russell Group, the University of Sheffield has a reputation for world-class teaching and research excellence across a wide range of disciplines. The University of Sheffield has been named University of the Year in the Times Higher Education Awards 2011 for its exceptional performance in research, teaching, access and business performance. In addition, the University has won four Queen’s Anniversary Prizes (1998, 2000, 2002, 2007), recognising the outstanding contribution by universities and colleges to the UK’s intellectual, economic, cultural and social life. One of the markers of a leading university is the quality of its alumni and Sheffield boasts five Nobel Prize winners among former staff and students. Its alumni have gone on to hold positions of great responsibility and influence all over the world, making significant contributions in their chosen fields. Research partners and clients include Boeing, Rolls-Royce, Unilever, Boots, AstraZeneca, GSK, Siemens, Yorkshire Water, and many more household names, as well as UK and overseas government agencies and charitable foundations.The University has well-established partnerships with a number of universities and major corporations, both in the UK and abroad. The White Rose University Consortium (White Rose) is a strategic partnership between three of the UK’s leading research universities of Leeds, Sheffield and York. Since its creation in 1997 White Rose has secured more than £100m into the universities.

6. Birkbeck is a world-class research and teaching institution, a vibrant centre of academic excellence and London’s only specialist provider of evening higher education. Birkbeck is ranked among the top one per cent of universities in the world in the Times Higher Education World University Rankings 2012. They encourage applications from students without traditional qualifications and have a wide range of programmes to suit every entry level. 18,000 students study with Birbeck every year. They join a community that is as diverse and cosmopolitan as London’s population.