Born to Run

or more realistically walk long distances. One of the most striking features of modern humans is that unlike any other primate we walk upright or bipedally. The coolest part of living in the genomic era is that with more complete genomes of primate species some of those long standing enigmas of human evolutionary history are being elucidated. An upcoming article in the journal Genome Research investigates gene duplications in 10 primate species and about 1/3 of human genes (6694) investigated contain a change in gene copy numbers in or more of the primate species (Dumas et al. 2007). One intriguing example in humans is the gene AQUAPORIN 7 (AQ7). Aquaporins are water channel genes that allow for effective movement of aqua between cell membranes. In humans this in important in adipose tissue which is important in energy storage as well as producing hormones such as leptin. This would suggest an important role for this gene family in thermoregulation and more efficient endurance in humans as opposed to other primates as suggested in this recent article by Sockal et al. 2007 on chimpanzee energetics

References

Sockal MD, Raichlen DA, Pontzer H. (2007). Chimpanzee locomotor energetics and the origin of human bipedalism. Proc Natl Acad Sci U S A. Jul 24;104(30):12265-9

Gene copy number variation spanning 60 million years of human and primate evolution

Laura Dumas¹, Young H. Kim², Anis Karimpour-Fard³, Michael Cox^1,4,5, Janet Hopkins^1,4,5, Jonathan R. Pollack², and James M. Sikela^1,4,5,6

¹ Human Medical Genetics Program, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado 80045, USA; ² Department of Pathology, Stanford University, Stanford, California 94305, USA; ³ Department of Preventative Medicine and Biometrics, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado 80045, USA; ⁴ Neuroscience Program, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado 80045, USA; ⁵ Department of Pharmacology, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado 80045, USA

Given the evolutionary importance of gene duplication to the emergence of species-specific traits, we have extended the application of cDNA array-based comparative genomic hybridization (aCGH) to survey gene duplications and losses genome-wide across 10 primate species, including human. Using human cDNA arrays that contained 41,126 cDNAs, corresponding to 24,473 unique human genes, we identified 4159 genes that likely represent most of the major lineage-specific gene copy number gains and losses that have occurred in these species over the past 60 million years. We analyzed 1,233,780 gene-to-gene data points and found that gene gains typically outnumbered losses (ratio of gains/losses = 2.34) and these frequently cluster in complex and dynamic genomic regions that are likely to serve as gene nurseries. Almost one-third of all human genes (6696) exhibit an aCGH- predicted change in copy number in one or more of these species, and within-species gene amplification is also evident. Many of the genes identified here are likely to be important to lineage-specific traits including, for example, human-specific duplications of the AQP7 gene, which represent intriguing candidates to underlie the key physiological adaptations in thermoregulation and energy utilization that permitted human endurance running.