Research in Focus
Dr. Timothy Bromage Introduces Human Paleobiomics, a New Direction in Evolution Research

Dr. Timothy Bromage

A micrograph of the tooth enamel of a two-million-year-old Paranthropus. The arrows in the inset point to incremental growth lines, a microanatomical feature used in the analysis of tooth evolution.

The 2.4-million-year-old human jaw from Malawi is attributed to the species Homo rudolfensis, the earliest representative of the genus Homo. This computed tomograph of a 1.5 mm slice through the teeth and jaw was color-coded to better reveal details of the internal structures for study.

NYU College of Dentistry paleoanthropologist Dr. Timothy Bromage is championing a new field of research that he is calling "human paleobiomics," which represents a new direction for the field of human evolution. Dr. Bromage has launched human paleobiomics with the help of a $1 million-plus grant from the Max Planck Society, which awarded Dr. Bromage the 2010 Max Planck Research Award in recognition of his achievements in establishing the modern field of growth, development, and life history in paleoanthropology.

Within the field of human paleobiomics, Dr. Bromage seeks to uncover connections between bone and tooth microstructure and the development, physiology, and metabolism of ancestral humans in different geographic and climate zones. Dr. Bromage, an adjunct professor of biomaterials and biomimetics and of basic science and craniofacial biology, aims to bring bone and tooth biology into the global mainstream of human evolution research.

The new endeavor is an outgrowth of Dr. Bromage's earlier pioneering research in bone and tooth micro-anatomy, including the discovery of a new biological clock, or long-term rhythm, hypothesized to control many metabolic functions. Dr. Bromage also observed a related pattern of incremental growth in skeletal bone tissue—the first time such an incremental rhythm has ever been observed in bone. The findings suggest that the same biological rhythm that controls incremental tooth and bone growth also affects bone and body size and many metabolic processes, including heart and respiration rates.

Human paleobiomics also involves searching for bone and tooth specimens in fossil-rich regions of Africa, and analyzing samples using advanced imaging techniques, such as 3D computer-simulated reconstruction, in a specially designed hard tissue research laboratory at NYUCD.

An early result of the human paleobiomics initiative was the discovery in 2010 of a 2.5-million year-old ancestral human tooth in Malawi by Dr. Bromage and Drs. Ottmar Kullmer and Friedemann Schrenk, two paleoanthropologists from the Senckenberg Research Institute in Frankfurt, Germany, host of the 2010 Max Planck Research Award. The tooth, belonging to the earliest known species of Homo—the same genus as modern man—was discovered several hundred meters from the site where a tooth belonging to Paranthropus, another hominid genus, was unearthed five years earlier.

While anthropologists believe that Homo and Paranthropus coexisted in Africa, Dr. Bromage's discovery, reported in an article in the Journal of Human Evolution, marks the first time that scientists have been able to determine that fossils found at the same site are from earliest Homo and earliest Paranthropus. Dr. Bromage's finding is thus the strongest support to date for the hypothesis that the two genera coexisted at the same time in the same biome.

"When I examined the micro-anatomy of the 2.5-million-year-old ancestral human tooth fragment, I found that it displayed characteristics that are associated more with those of earliest Homo than other early human species," said Dr. Bromage.

"Those characteristics reflect an adaptation to the environmental changes occurring 2.5 million years ago, when there was a significant cooling of the earth's climate. As the earth cooled, habitats became more arid, vegetation became tougher, and mammals adapted by developing larger teeth with more chewing capacity," he added.

Dr. Bromage plans additional research on the evolution of bone and tooth microanatomy in these and other hominid genera.